Articoli di riviste: "Biofilms"

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Cole, Stephanie J., Angela R. Records, Mona W. Orr, Sara B. Linden e Vincent T. Lee. "Catheter-Associated Urinary Tract Infection by Pseudomonas aeruginosa Is Mediated by Exopolysaccharide-Independent Biofilms". Infection and Immunity 82, n. 5 (4 marzo 2014): 2048–58. http://dx.doi.org/10.1128/iai.01652-14.

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ABSTRACTPseudomonas aeruginosais an opportunistic human pathogen that is especially adept at forming surface-associated biofilms.P. aeruginosacauses catheter-associated urinary tract infections (CAUTIs) through biofilm formation on the surface of indwelling catheters.P. aeruginosaencodes three extracellular polysaccharides, PEL, PSL, and alginate, and utilizes the PEL and PSL polysaccharides to form biofilmsin vitro; however, the requirement of these polysaccharides duringin vivoinfections is not well understood. Here we show in a murine model of CAUTI that PAO1, a strain harboringpel,psl, andalggenes, and PA14, a strain harboringpelandalggenes, form biofilms on the implanted catheters. To determine the requirement of exopolysaccharide duringin vivobiofilm infections, we tested isogenic mutants lacking thepel,psl, andalgoperons and showed that PA14 mutants lacking these operons can successfully form biofilms on catheters in the CAUTI model. To determine the host factor(s) that induces the ΔpelDmutant to form biofilm, we tested mouse, human, and artificial urine and show that urine can induce biofilm formation by the PA14 ΔpelDmutant. By testing the major constituents of urine, we show that urea can induce apel-,psl-, andalg-independent biofilm. Thesepel-,psl-, andalg-independent biofilms are mediated by the release of extracellular DNA. Treatment of biofilms formed in urea with DNase I reduced the biofilm, indicating that extracellular DNA supports biofilm formation. Our results indicate that the opportunistic pathogenP. aeruginosautilizes a distinct program to form biofilms that are independent of exopolysaccharides during CAUTI.

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Kesel, Sara, Stefan Grumbein, Ina Gümperlein, Marwa Tallawi, Anna-Kristina Marel, Oliver Lieleg e Madeleine Opitz. "Direct Comparison of Physical Properties of Bacillus subtilis NCIB 3610 and B-1 Biofilms". Applied and Environmental Microbiology 82, n. 8 (12 febbraio 2016): 2424–32. http://dx.doi.org/10.1128/aem.03957-15.

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ABSTRACTMany bacteria form surface-attached communities known as biofilms. Due to the extreme resistance of these bacterial biofilms to antibiotics and mechanical stresses, biofilms are of growing interest not only in microbiology but also in medicine and industry. Previous studies have determined the extracellular polymeric substances present in the matrix of biofilms formed byBacillus subtilisNCIB 3610. However, studies on the physical properties of biofilms formed by this strain are just emerging. In particular, quantitative data on the contributions of biofilm matrix biopolymers to these physical properties are lacking. Here, we quantitatively investigated three physical properties ofB. subtilisNCIB 3610 biofilms: the surface roughness and stiffness and the bulk viscoelasticity of these biofilms. We show how specific biomolecules constituting the biofilm matrix formed by this strain contribute to those biofilm properties. In particular, we demonstrate that the surface roughness and surface elasticity of 1-day-old NCIB 3610 biofilms are strongly affected by the surface layer protein BslA. For a second strain,B. subtilisB-1, which forms biofilms containing mainly γ-polyglutamate, we found significantly different physical biofilm properties that are also differently affected by the commonly used antibacterial agent ethanol. We show that B-1 biofilms are protected from ethanol-induced changes in the biofilm's stiffness and that this protective effect can be transferred to NCIB 3610 biofilms by the sole addition of γ-polyglutamate to growing NCIB 3610 biofilms. Together, our results demonstrate the importance of specific biofilm matrix components for the distinct physical properties ofB. subtilisbiofilms.

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Kurniawan, Andi, Siti Mariyah Ulfa e Chamidah Chamidah. "The Biosorption of Copper(II) Using a Natural Biofilm Formed on the Stones from the Metro River, Malang City, Indonesia". International Journal of Microbiology 2022 (27 settembre 2022): 1–6. http://dx.doi.org/10.1155/2022/9975333.

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Biofilm is the predominant habitat of microbes in aquatic ecosystems. Microhabitat inside the biofilm matrix is a nutrient-rich environment promoted by the adsorption of nutrient ions from the surrounding water. Biofilms can not only adsorb ions that are nutrients but also other ions, such as heavy metals. The ability of biofilm to attract and retain heavy metals, such as copper(II), makes biofilms a promising biosorbent for water pollution treatment. The present study analyzes the characteristics of copper(II) adsorption by biofilms naturally formed in the river. The biofilms used in this study grow naturally on the stones in the Metro River in Malang City, Indonesia. Methods to analyze the adsorption characteristics of copper(II) by biofilms were kinetics of the adsorption and adsorption isotherm. The maximum adsorption amount and the adsorption equilibrium constant were calculated using a variant of the Langmuir isotherm model. In addition, the presence of the functional groups as suggested binding sites in biofilm polymers was investigated using the Fourier transform infrared (FTIR) analysis. The results indicate that copper(II)’s adsorption to the biofilm is a physicochemical process. The adsorption of copper(II) is fitted well with the Langmuir isotherm model, suggesting that the adsorption of copper(II) to a biofilm is due to the interaction between the adsorption sites on the biofilm and the ions. The biofilm’s maximum absorption capacity for copper(II) is calculated to be 2.14 mg/wet-g of biofilm, with the equilibrium rate constant at 0.05 L/mg. Therefore, the biofilms on the stones from river can be a promising biosorbent of copper(II) pollution in aquatic ecosystems.

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Vestweber, Pia Katharina, Jana Wächter, Viktoria Planz, Nathalie Jung e Maike Windbergs. "The interplay of Pseudomonas aeruginosa and Staphylococcus aureus in dual-species biofilms impacts development, antibiotic resistance and virulence of biofilms in in vitro wound infection models". PLOS ONE 19, n. 5 (28 maggio 2024): e0304491. http://dx.doi.org/10.1371/journal.pone.0304491.

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Due to high tolerance to antibiotics and pronounced virulence, bacterial biofilms are considered a key factor and major clinical challenge in persistent wound infections. They are typically composed of multiple species, whose interactions determine the biofilm’s structural development, functional properties and thus the progression of wound infections. However, most attempts to study bacterial biofilms in vitro solely rely on mono-species populations, since cultivating multi-species biofilms, especially for prolonged periods of time, poses significant challenges. To address this, the present study examined the influence of bacterial composition on structural biofilm development, morphology and spatial organization, as well as antibiotic tolerance and virulence on human skin cells in the context of persistent wound infections. By creating a wound-mimetic microenvironment, the successful cultivation of dual-species biofilms of two of the most prevalent wound pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, was realized over a period of 72 h. Combining quantitative analysis with electron microscopy and label-free imaging enabled a comprehensive evaluation of the dynamics of biofilm formation and matrix secretion, revealing a twofold increased maturation of dual-species biofilms. Antibiotic tolerance was comparable for both mono-species cultures, however, dual-species communities showed a 50% increase in tolerance, mediated by a significantly reduced penetration of the applied antibiotic into the biofilm matrix. Further synergistic effects were observed, where dual-species biofilms exacerbated wound healing beyond the effects observed from either Pseudomonas or Staphylococcus. Consequently, predicting biofilm development, antimicrobial tolerance and virulence for multi-species biofilms based solely on the results from mono-species biofilms is unreliable. This study underscores the substantial impact of a multi-species composition on biofilm functional properties and emphasizes the need to tailor future studies reflecting the bacterial composition of the respective in vivo situation, leading to a more comprehensive understanding of microbial communities in the context of basic microbiology and the development of effective treatments.

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Sanchez, Carlos J., Kevin S. Akers, Desiree R. Romano, Ronald L. Woodbury, Sharanda K. Hardy, Clinton K. Murray e Joseph C. Wenke. "d-Amino Acids Enhance the Activity of Antimicrobials against Biofilms of Clinical Wound Isolates of Staphylococcus aureus and Pseudomonas aeruginosa". Antimicrobial Agents and Chemotherapy 58, n. 8 (19 maggio 2014): 4353–61. http://dx.doi.org/10.1128/aac.02468-14.

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ABSTRACTWithin wounds, microorganisms predominantly exist as biofilms. Biofilms are associated with chronic infections and represent a tremendous clinical challenge. As antibiotics are often ineffective against biofilms, use of dispersal agents as adjunctive, topical therapies for the treatment of wound infections involving biofilms has gained interest. We evaluatedin vitrothe dispersive activity ofd-amino acids (d-AAs) on biofilms from clinical wound isolates ofStaphylococcus aureusandPseudomonas aeruginosa; moreover, we determined whether combinations ofd-AAs and antibiotics (clindamycin, cefazolin, oxacillin, rifampin, and vancomycin forS. aureusand amikacin, colistin, ciprofloxacin, imipenem, and ceftazidime forP. aeruginosa) enhance activity against biofilms.d-Met,d-Phe, andd-Trp at concentrations of ≥5 mM effectively dispersed preformed biofilms ofS. aureusandP. aeruginosaclinical isolates, an effect that was enhanced when they were combined as an equimolar mixture (d-Met/d-Phe/d-Trp). When combined withd-AAs, the activity of rifampin was significantly enhanced against biofilms of clinical isolates ofS. aureus, as indicated by a reduction in the minimum biofilm inhibitory concentration (MBIC) (from 32 to 8 μg/ml) and a >2-log reduction of viable biofilm bacteria compared to treatment with antibiotic alone. The addition ofd-AAs was also observed to enhance the activity of colistin and ciprofloxacin against biofilms ofP. aeruginosa, reducing the observed MBIC and the number of viable bacteria by >2 logs and 1 log at 64 and 32 μg/ml in contrast to antibiotics alone. These findings indicate that the biofilm dispersal activity ofd-AAs may represent an effective strategy, in combination with antimicrobials, to release bacteria from biofilms, subsequently enhancing antimicrobial activity.

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Tran, Hoai My, Hien Tran, Marsilea A. Booth, Kate E. Fox, Thi Hiep Nguyen, Nhiem Tran e Phong A. Tran. "Nanomaterials for Treating Bacterial Biofilms on Implantable Medical Devices". Nanomaterials 10, n. 11 (13 novembre 2020): 2253. http://dx.doi.org/10.3390/nano10112253.

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Bacterial biofilms are involved in most device-associated infections and remain a challenge for modern medicine. One major approach to addressing this problem is to prevent the formation of biofilms using novel antimicrobial materials, device surface modification or local drug delivery; however, successful preventive measures are still extremely limited. The other approach is concerned with treating biofilms that have already formed on the devices; this approach is the focus of our manuscript. Treating biofilms associated with medical devices has unique challenges due to the biofilm’s extracellular polymer substance (EPS) and the biofilm bacteria’s resistance to most conventional antimicrobial agents. The treatment is further complicated by the fact that the treatment must be suitable for applying on devices surrounded by host tissue in many cases. Nanomaterials have been extensively investigated for preventing biofilm formation on medical devices, yet their applications in treating bacterial biofilm remains to be further investigated due to the fact that treating the biofilm bacteria and destroying the EPS are much more challenging than preventing adhesion of planktonic bacteria or inhibiting their surface colonization. In this highly focused review, we examined only studies that demonstrated successful EPS destruction and biofilm bacteria killing and provided in-depth description of the nanomaterials and the biofilm eradication efficacy, followed by discussion of key issues in this topic and suggestion for future development.

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Alasil, Saad Musbah, Rahmat Omar, Salmah Ismail, Mohd Yasim Yusof, Ghulam N. Dhabaan e Mahmood Ameen Abdulla. "Evidence of Bacterial Biofilms among Infected and Hypertrophied Tonsils in Correlation with the Microbiology, Histopathology, and Clinical Symptoms of Tonsillar Diseases". International Journal of Otolaryngology 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/408238.

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Diseases of the tonsils are becoming more resistant to antibiotics due to the persistence of bacteria through the formation of biofilms. Therefore, understanding the microbiology and pathophysiology of such diseases represent an important step in the management of biofilm-related infections. We have isolated the microorganisms, evaluated their antimicrobial susceptibility, and detected the presence of bacterial biofilms in tonsillar specimens in correlation with the clinical manifestations of tonsillar diseases. Therefore, a total of 140 palatine tonsils were collected from 70 patients undergoing tonsillectomy at University Malaya Medical Centre. The most recovered isolate wasStaphylococcus aureus(39.65%) followed byHaemophilus influenzae(18.53%). There was high susceptibility against all selected antibiotics except for cotrimoxazole. Bacterial biofilms were detected in 60% of patients and a significant percentage of patients demonstrated infection manifestation rather than obstruction. In addition, an association between clinical symptoms like snore, apnea, nasal obstruction, and tonsillar hypertrophy was found to be related to the microbiology of tonsils particularly to the presence of biofilms. In conclusion, evidence of biofilms in tonsils in correlation with the demonstrated clinical symptoms explains the recalcitrant nature of tonsillar diseases and highlights the importance of biofilm’s early detection and prevention towards better therapeutic management of biofilm-related infections.

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Hengzhuang, Wang, Oana Ciofu, Liang Yang, Hong Wu, Zhijun Song, Antonio Oliver e Niels Høiby. "High β-Lactamase Levels Change the Pharmacodynamics of β-Lactam Antibiotics in Pseudomonas aeruginosa Biofilms". Antimicrobial Agents and Chemotherapy 57, n. 1 (22 ottobre 2012): 196–204. http://dx.doi.org/10.1128/aac.01393-12.

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ABSTRACTResistance to β-lactam antibiotics is a frequent problem inPseudomonas aeruginosalung infection of cystic fibrosis (CF) patients. This resistance is mainly due to the hyperproduction of chromosomally encoded β-lactamase and biofilm formation. The purpose of this study was to investigate the role of β-lactamase in the pharmacokinetics (PK) and pharmacodynamics (PD) of ceftazidime and imipenem onP. aeruginosabiofilms.P. aeruginosaPAO1 and its corresponding β-lactamase-overproducing mutant, PAΔDDh2Dh3, were used in this study. Biofilms of these two strains in flow chambers, microtiter plates, and on alginate beads were treated with different concentrations of ceftazidime and imipenem. The kinetics of antibiotics on the biofilms was investigatedin vitroby time-kill methods. Time-dependent killing of ceftazidime was observed in PAO1 biofilms, but concentration-dependent killing activity of ceftazidime was observed for β-lactamase-overproducing biofilms ofP. aeruginosain all three models. Ceftazidime showed time-dependent killing on planktonic PAO1 and PAΔDDh2Dh3. This difference is probably due to the special distribution and accumulation in the biofilm matrix of β-lactamase, which can hydrolyze the β-lactam antibiotics. The PK/PD indices of the AUC/MBIC andCmax/MBIC (AUC is the area under concentration-time curve, MBIC is the minimal biofilm-inhibitory concentration, andCmaxis the maximum concentration of drug in serum) are probably the best parameters to describe the effect of ceftazidime in β-lactamase-overproducingP. aeruginosabiofilms. Meanwhile, imipenem showed time-dependent killing on both PAO1 and PAΔDDh2Dh3 biofilms. An inoculum effect of β-lactams was found for both planktonic and biofilmP. aeruginosacells. The inoculum effect of ceftazidime for the β-lactamase-overproducing mutant PAΔDDh2Dh3 biofilms was more obvious than for PAO1 biofilms, with a requirement of higher antibiotic concentration and a longer period of treatment.

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Oliveira, Maria Alcionéia Carvalho de, Gabriela de Morais Gouvêa Lima, Thalita M. Castaldelli Nishime, Aline Vidal Lacerda Gontijo, Beatriz Rossi Canuto de Menezes, Marcelo Vidigal Caliari, Konstantin Georgiev Kostov e Cristiane Yumi Koga-Ito. "Inhibitory Effect of Cold Atmospheric Plasma on Chronic Wound-Related Multispecies Biofilms". Applied Sciences 11, n. 12 (11 giugno 2021): 5441. http://dx.doi.org/10.3390/app11125441.

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The presence of microbial biofilms in the wounds affects negatively the healing process and can contribute to therapeutic failures. This study aimed to establish the effective parameters of cold atmospheric plasma (CAP) against wound-related multispecies and monospecies biofilms, and to evaluate the cytotoxicity and genotoxicity of the protocol. Monospecies and multispecies biofilms were formed by methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Enterococcus faecalis. The monospecies biofilms were grown in 96 wells plates and multispecies biofilm were formed on collagen membranes. The biofilms were exposed to helium CAP for 1, 3, 5 and 7 min. In monospecies biofilms, the inhibitory effect was detected after 1 min of exposure for E. faecalis and after 3 min for MRSA. A reduction in P. aeruginosa biofilm’s viability was detected after 7 min of exposure. For the multispecies biofilms, the reduction in the overall viability was detected after 5 min of exposure to CAP. Additionally, cytotoxicity and genotoxicity were evaluated by MTT assay and static cytometry, respectively. CAP showed low cytotoxicity and no genotoxicity to mouse fibroblastic cell line (3T3). It could be concluded that He-CAP showed inhibitory effect on wound-related multispecies biofilms, with low cytotoxicity and genotoxicity to mammalian cells. These findings point out the potential application of CAP in wound care.

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Jabber Al-Saady, Mohammed Abd Ali, Nawfal H. Aldujaili, Shiama Rabeea Banoon e Aswan Al-Abboodi. "Antimicrobial properties of nanoparticles in biofilms". Bionatura 7, n. 4 (15 dicembre 2022): 1–9. http://dx.doi.org/10.21931/rb/2022.07.04.71.

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Biofilm is a structure in the shape of a surface adherent composed of a microbe’s community and plays a crucial role in stimulating the infection. Due to the Biofilm’s complex structure compared with the individual microbe, it occasionally develops recalcitrant to the host immune system, which may lead to antibiotic resistance. The National Institutes of Health has reported that more than 80% of bacterial infections are caused by biofilm formation. Removing biofilm-mediated infections is an immense challenge that should involve various strategies that may induce sensitive and effective antibiofilm therapy. In the last decade, nanoparticle NPs application has been employed as one of the strategies that have grown great stimulus to target antibiofilm treatment due to their unique properties. Nanobiotechnology holds promise for the future because it has various antimicrobial properties in biofilms and promising new drug delivery methods that stand out from conventional antibiotics. Studying the interaction between the Biofilm and the nanoparticles can deliver additional insights regarding the mechanism of biofilm regulation. This review article will define synthetic nanoparticle NPs, their medical applications, and their potential use against a broad range of microbial biofilms in the coming years. The motivation of the current review is to focus on NPs materials’ properties and applications and their use as antimicrobial agents to fight resistant infections, which can locally terminate bacteria without being toxic to the surrounding tissue and share its role in improving human health in the future. Keywords: Biofilms, antimicrobial, nanoparticles, bio-nanotechnology, drug resistance.

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Fabbri, S., D. A. Johnston, A. Rmaile, B. Gottenbos, M. De Jager, M. Aspiras, E. M. Starke, M. T. Ward e P. Stoodley. "High-Velocity Microsprays Enhance Antimicrobial Activity in Streptococcus mutans Biofilms". Journal of Dental Research 95, n. 13 (1 ottobre 2016): 1494–500. http://dx.doi.org/10.1177/0022034516662813.

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Streptococcus mutans in dental plaque biofilms play a role in caries development. The biofilm’s complex structure enhances the resistance to antimicrobial agents by limiting the transport of active agents inside the biofilm. The authors assessed the ability of high-velocity water microsprays to enhance delivery of antimicrobials into 3-d-old S. mutans biofilms. Biofilms were exposed to a 90° or 30° impact, first using a 1-µm tracer bead solution (109 beads/mL) and, second, a 0.2% chlorhexidine (CHX) or 0.085% cetylpyridinium chloride (CPC) solution. For comparison, a 30-s diffusive transport and simulated mouthwash were also performed. Confocal microscopy was used to determine number and relative bead penetration depth into the biofilm. Assessment of antimicrobial penetration was determined by calculating the killing depth detected by live/dead viability staining. The authors first demonstrated that the microspray was able to deliver significantly more microbeads deeper in the biofilm compared with diffusion and mouthwashing exposures. Next, these experiments revealed that the microspray yielded better antimicrobial penetration evidenced by deeper killing inside the biofilm and a wider killing zone around the zone of clearance than diffusion alone. Interestingly the 30° impact in the distal position delivered approximately 16 times more microbeads and yielded approximately 20% more bacteria killing (for both CHX and CPC) than the 90° impact. These data suggest that high-velocity water microsprays can be used as an effective mechanism to deliver microparticles and antimicrobials inside S. mutans biofilms. High shear stresses generated at the biofilm-burst interface might have enhanced bead and antimicrobial delivery inside the remaining biofilm by combining forced advection into the biofilm matrix and physical restructuring of the biofilm itself. Further, the impact angle has potential to be optimized both for biofilm removal and active agents’ delivery inside biofilm in those protected areas where some biofilm might remain.

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Vyas, Heema K. N., Emma-Jayne Proctor, Jason McArthur, Jody Gorman e Martina Sanderson-Smith. "Current Understanding of Group A Streptococcal Biofilms". Current Drug Targets 20, n. 9 (11 giugno 2019): 982–93. http://dx.doi.org/10.2174/1389450120666190405095712.

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Background:It has been proposed that GAS may form biofilms. Biofilms are microbial communities that aggregate on a surface, and exist within a self-produced matrix of extracellular polymeric substances. Biofilms offer bacteria an increased survival advantage, in which bacteria persist, and resist host immunity and antimicrobial treatment. The biofilm phenotype has long been recognized as a virulence mechanism for many Gram-positive and Gram-negative bacteria, however very little is known about the role of biofilms in GAS pathogenesis.Objective:This review provides an overview of the current knowledge of biofilms in GAS pathogenesis. This review assesses the evidence of GAS biofilm formation, the role of GAS virulence factors in GAS biofilm formation, modelling GAS biofilms, and discusses the polymicrobial nature of biofilms in the oropharynx in relation to GAS.Conclusion:Further study is needed to improve the current understanding of GAS as both a monospecies biofilm, and as a member of a polymicrobial biofilm. Improved modelling of GAS biofilm formation in settings closely mimicking in vivo conditions will ensure that biofilms generated in the lab closely reflect those occurring during clinical infection.

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Simões, M., S. Cleto, M. O. Pereira e M. J. Vieira. "Influence of biofilm composition on the resistance to detachment". Water Science and Technology 55, n. 8-9 (1 aprile 2007): 473–80. http://dx.doi.org/10.2166/wst.2007.293.

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Bacillus cereus and Pseudomonas fluorescens were used to develop monoculture biofilms in a bioreactor rotating system using a stainless steel cylinder for biofilm formation. The biofilms were allowed to grow for 7 days, exposed continuously to a Reynolds number of agitation (ReA) of 2,400. Afterwards, the biofilms were characterised in terms of respiratory activity, amount of biomass, cellular density, cellular size and total and extracellular proteins and polysaccharides. The biofilm mechanical stability was assessed by sequential submission of the biofilms to increasing ReA, respectively, 4,000, 8,100, 12,100 and 16,100. The results showed that P. fluorescens biofilms were five times more active, had a higher amount of biomass, cellular density, a reduced cellular size and a four-fold higher amount of extracellular proteins and polysaccharides than B. cereus biofilms. The application of shear stress forces higher than the one under which the biofilm was formed (ReA=2,400) caused biomass removal. The high percentage of removal occurred with the implementation of a ReA of 8,100 for both B. cereus and P. fluorescens biofilms. The total series of ReA did not give rise to total biofilm removal, as only about 76% of P. fluorescens biofilm mass and 53% of B. cereus biofilm mass were detached from the cylinders. This latter result evidences that B. cereus had a higher mechanical stability than P. fluorescens biofilms. The overall results demonstrate that P. fluorescens and B. cereus formed physiologically distinct biofilms, B. cereus biofilms mainly being constituted by cells and P. fluorescens biofilms largely constituted by extracellular proteins and polysaccharides. B. cereus biofilms had a substantially higher mechanical stability than P. fluorescens biofilms.

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Stinson, Kevin J. "Peering into the matrix: A look at biofilms and their inherent antibiotic resistance". SURG Journal 6, n. 2 (12 luglio 2013): 71–77. http://dx.doi.org/10.21083/surg.v6i2.2201.

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Biofilms are increasingly being regarded as the predominant form of bacterial growth in natural settings. These structures consist of bacterial cells immobilized at a surface and encased in a self-produced matrix of extracellular polymeric substances. In clinical settings, biofilms are the cause of persistent infections that are difficult to clear through the action of the host immune system. Biofilm-encased cells are also associated with increased levels of antibiotic resistance compared to their planktonic counterparts. The result is increased morbidity and mortality when biofilms are associated with disease. In this review, the focus of discussion will be the various mechanisms of antibiotic resistance common to biofilms and the role these mechanisms play in the pathogenesis of major clinically-relevant microorganisms. Antibiotic penetration, altered microenvironments, phenotypic variation, and adaptive resistance mechanisms are all key players in the development of antibiotic resistance in bacterial biofilms. Though the relative significance of each individual mechanism varies, when combined they confer extensive protection to the biofilm’s cellular populations. Keywords: biofilms; antibiotic resistance (mechanisms of); clinical applications; disease; antibiotic penetration; altered microenvironments; phenotypic variation; adaptive resistance; review

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Rocco, Christopher J., Lauren O. Bakaletz e Steven D. Goodman. "Targeting the HUβ Protein PreventsPorphyromonas gingivalisfrom Entering into Preexisting Biofilms". Journal of Bacteriology 200, n. 11 (5 febbraio 2018): e00790-17. http://dx.doi.org/10.1128/jb.00790-17.

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ABSTRACTThe oral cavity is home to a wide variety of bacterial species, both commensal, such as various streptococcal species, and pathogenic, such asPorphyromonas gingivalis, one of the main etiological agents of periodontal disease. Our understanding of how these bacteria ultimately cause disease is highly dependent upon understanding how they coexist and interact with one another in biofilm communities and the mechanisms by which biofilms are formed. Our research has demonstrated that the DNABII family of DNA-binding proteins are important components of the extracellular DNA (eDNA)-dependent matrix of bacterial biofilms and that sequestering these proteins via protein-specific antibodies results in the collapse of the biofilm structure and release of the resident bacteria. While the high degree of similarity among the DNABII family of proteins has allowed antibodies derived against specific DNABII proteins to disrupt biofilms formed by a wide range of bacterial pathogens, the DNABII proteins ofP. gingivalishave proven to be antigenically distinct, allowing us to determine if we can use anti-P. gingivalisHUβ antibodies to specifically target this species for removal from a mixed-species biofilm. Importantly, despite forming homotypic biofilmsin vitro,P. gingivalismust enter preexisting biofilmsin vivoin order to persist within the oral cavity. The data presented here indicate that antibodies derived against theP. gingivalisDNABII protein, HUβ, reduce by half the amount ofP. gingivalisorganisms entering into preexisting biofilm formed by four oral streptococcal species. These results support our efforts to develop methods for preventing and treating periodontal disease.IMPORTANCEPeriodontitis is one of the most prevalent chronic infections, affecting 40 to 50% of the population of the United States. The root cause of periodontitis is the presence of bacterial biofilms within the gingival space, withPorphyromonas gingivalisbeing strongly associated with the development of the disease. Periodontitis also increases the risk of secondary conditions and infections such as atherosclerosis and infective endocarditis caused by oral streptococci. To induce periodontitis,P. gingivalisneeds to incorporate into preformed biofilms, with oral streptococci being important binding partners. Our research demonstrates that targeting DNABII proteins with an antibody disperses oral streptococcus biofilm and preventsP. gingivalisentry into oral streptococcus biofilm. These results suggest potential therapeutic treatments for endocarditis caused by streptococci as well as periodontitis.

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Ito, Akinobu, Asami Taniuchi, Thithiwat May, Koji Kawata e Satoshi Okabe. "Increased Antibiotic Resistance of Escherichia coli in Mature Biofilms". Applied and Environmental Microbiology 75, n. 12 (17 aprile 2009): 4093–100. http://dx.doi.org/10.1128/aem.02949-08.

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ABSTRACT Biofilms are considered to be highly resistant to antimicrobial agents. Several mechanisms have been proposed to explain this high resistance of biofilms, including restricted penetration of antimicrobial agents into biofilms, slow growth owing to nutrient limitation, expression of genes involved in the general stress response, and emergence of a biofilm-specific phenotype. However, since combinations of these factors are involved in most biofilm studies, it is still difficult to fully understand the mechanisms of biofilm resistance to antibiotics. In this study, the antibiotic susceptibility of Escherichia coli cells in biofilms was investigated with exclusion of the effects of the restricted penetration of antimicrobial agents into biofilms and the slow growth owing to nutrient limitation. Three different antibiotics, ampicillin (100 μg/ml), kanamycin (25 μg/ml), and ofloxacin (10 μg/ml), were applied directly to cells in the deeper layers of mature biofilms that developed in flow cells after removal of the surface layers of the biofilms. The results of the antibiotic treatment analyses revealed that ofloxacin and kanamycin were effective against biofilm cells, whereas ampicillin did not kill the cells, resulting in regrowth of the biofilm after the ampicillin treatment was discontinued. LIVE/DEAD staining revealed that a small fraction of resistant cells emerged in the deeper layers of the mature biofilms and that these cells were still alive even after 24 h of ampicillin treatment. Furthermore, to determine which genes in the biofilm cells are induced, allowing increased resistance to ampicillin, global gene expression was analyzed at different stages of biofilm formation, the attachment, colony formation, and maturation stages. The results showed that significant changes in gene expression occurred during biofilm formation, which were partly induced by rpoS expression. Based on the experimental data, it is likely that the observed resistance of biofilms can be attributed to formation of ampicillin-resistant subpopulations in the deeper layers of mature biofilms but not in young colony biofilms and that the production and resistance of the subpopulations were aided by biofilm-specific phenotypes, like slow growth and induction of rpoS-mediated stress responses.

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Sari, Rafika, Sylvia Utami Tunjung Pratiwi, Yosi Bayu Murti e Ema Damayanti. "Potential of Indonesian Plants as Polymicrobial Anti-Biofilm". Borneo Journal of Pharmacy 7, n. 1 (29 febbraio 2024): 63–79. http://dx.doi.org/10.33084/bjop.v7i1.5645.

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Biofilm infection occurs in 80% of chronic infections caused by 60% of biofilms from plankton cells and polymicrobial biofilms. Due to synergistic interactions between species, infections caused by polymicrobial biofilms are more virulent than monospecies biofilm infections. New anti-biofilm candidates are constantly being developed by tracing the content of active compounds from medicinal plants native to Indonesia. The need to find new plant sources that have the potential as anti-biofilms is increasingly needed along with increasing microbial resistance. Various studies show that active compounds that have anti-biofilm potential are polyphenols, quercetin, curcumin, gallic acid, and ferulic acid. The mechanism of action of anti-biofilms is through the prevention of attachment and formation of biofilms, inhibition of quorum sensing, and inhibition of gene expression in microbes.

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Zhang, T. C., Y. C. Fu e P. L. Bishop. "Competition in biofilms". Water Science and Technology 29, n. 10-11 (1 ottobre 1994): 263–70. http://dx.doi.org/10.2166/wst.1994.0769.

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Competitions in biofilms for substrate and space have been studied by using a microelectrode technique and a microslicing technique. Three different kinds of biofilms, cultured by laboratory-scale rotating drum biofilm reactors (RDBR) with synthetic wastewater, have been used as test materials. Oxygen, ammonium-nitrogen, nitrate-nitrogen, and pH concentration profiles in the biofilms were measured using microelectrodes. Experimental results showed that: 1) an increase of organic loading rate would result in a decrease of DO concentration in the biofilm. However, after the organic loading rate exceeded a certain value, the oxygen profiles within the biofilm did not change any more; 2) Heterotrophs competed for oxygen with nitrifiers, which resulted in the inhibition of nitrification because of the shortage of oxygen. Glucose itself, however, did not inhibit the nitrification processes; and 3) The competition for substrate in biofilms resulted in a stratified biofilm structure. Experiments showed that competition in biofilms resulted in non-uniform spatial distributions of bacterial populations and metabolically active bacteria. The spatial distributions of biotic and abiotic components in turn affected the substrate transfer and substrate competition within the biofilm. Traditional biofilm modelling will fail in many cases if they are based on substrate removal kinetics and uniform distributions of biofilm properties.

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19

Parga, Ana, Sabela Balboa, Paz Otero-Casal e Ana Otero. "New Preventive Strategy against Oral Biofilm Formation in Caries-Active Children: An In Vitro Study". Antibiotics 12, n. 8 (31 luglio 2023): 1263. http://dx.doi.org/10.3390/antibiotics12081263.

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Quorum quenching (QQ) is the inhibition of bacterial communication, i.e., quorum sensing (QS). QS is a key mechanism in regulating biofilm formation and phenotype in complex bacterial communities, such as those found within cariogenic biofilms. Whereas QQ approaches were shown to effectively reduce biomass, knowledge of their impact on the taxonomic composition of oral polymicrobial biofilms remains scarce. Here, we investigate the effect of the QQ lactonase Aii20J on biomass production and taxonomical composition of biofilms. We collected supragingival plaque samples from 10 caries-free and 10 caries-active children and cultured them to generate in vitro biofilms. We describe significant biomass reductions upon Aii20J exposure, as assessed by crystal violet assays. Taxonomical profiling using 16S rRNA gene amplicon sequencing revealed no significant changes in bacterial composition at the genus level. Interestingly, at the species level Aii20J-treatment increased the abundance of Streptococcus cristatus and Streptococcus salivarius. Both S. cristatus and S. salivarius express pH-buffering enzymes (arginine deiminase and urease, respectively) that catalyze ammonia production, thereby potentially raising local pH and counteracting the biofilm’s cariogenic potential. Within the limitations of the study, our findings provide evidence of the biofilm-modulating ability of QQ and offer novel insights into alternative strategies to restore homeostasis within dysbiotic ecosystems.

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20

Ferris, Ryan A., Patrick M. McCue, Grace I. Borlee, Kristen D. Loncar, Margo L. Hennet e Bradley R. Borlee. "In VitroEfficacy of Nonantibiotic Treatments on Biofilm Disruption of Gram-Negative Pathogens and anIn VivoModel of Infectious Endometritis Utilizing Isolates from the Equine Uterus". Journal of Clinical Microbiology 54, n. 3 (30 dicembre 2015): 631–39. http://dx.doi.org/10.1128/jcm.02861-15.

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Abstract (sommario):

In this study, we evaluated the ability of the equine clinical treatmentsN-acetylcysteine, EDTA, and hydrogen peroxide to disruptin vitrobiofilms and kill equine reproductive pathogens (Escherichia coli,Pseudomonas aeruginosa, orKlebsiella pneumoniae) isolated from clinical cases.N-acetylcysteine (3.3%) decreased biofilm biomass and killed bacteria within the biofilms ofE. coliisolates. The CFU of recoverableP. aeruginosaandK. pneumoniaeisolates were decreased, but the biofilm biomass was unchanged. Exposure to hydrogen peroxide (1%) decreased the biofilm biomass and reduced the CFU ofE. coliisolates,K. pneumoniaeisolates were observed to have a reduction in CFU, and minimal effects were observed forP. aeruginosaisolates. Chelating agents (EDTA formulations) reducedE. coliCFU but were ineffective at disrupting preformed biofilms or decreasing the CFU ofP. aeruginosaandK. pneumoniaewithin a biofilm. No single nonantibiotic treatment commonly used in equine veterinary practice was able to reduce the CFU and biofilm biomass of all three Gram-negative species of bacteria evaluated. Anin vivoequine model of infectious endometritis was also developed to monitor biofilm formation, utilizing bioluminescence imaging with equineP. aeruginosaisolates from this study. Following infection, the endometrial surface contained focal areas of bacterial growth encased in a strongly adherent “biofilm-like” matrix, suggesting that biofilms are present during clinical cases of infectious equine endometritis. Our results indicate that Gram-negative bacteria isolated from the equine uterus are capable of producing a biofilmin vitro, andP. aeruginosais capable of producing biofilm-like materialin vivo.

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21

Beyenal, H., A. Tanyolaç e Z. Lewandowski. "Measurement of local effective diffusivity in heterogeneous biofilms". Water Science and Technology 38, n. 8-9 (1 ottobre 1998): 171–78. http://dx.doi.org/10.2166/wst.1998.0804.

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Abstract (sommario):

We have developed a novel technique to measure local effective diffusivity distribution in heterogeneous biofilms. Mobile microelectrodes (tip diameter 10 μm) and the limiting current technique were employed to measure the effective diffusivity of electroactive species introduced to natural and artificial biofilms. We calibrated the microelectrodes in artificial biofilms of known effective diffusivity and known density. In mixed population biofilms, local effective diffusivity varied from one location to another and decreased toward the bottom of the biofilm. We related local effective diffusivity to local biofilm density using an empirical equation. Surface-averaged biomass density depended on liquid flow velocity at which the biofilms were grown. The higher the flow velocity, the denser were the biofilms. Our technique permits fast evaluation of local effective diffusivity and biofilm density in heterogeneous biofilms.

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22

Burmï¿½lle, Mette, Jeremy S. Webb, Dhana Rao, Lars H. Hansen, Sï¿½ren J. Sï¿½rensen e Staffan Kjelleberg. "Enhanced Biofilm Formation and Increased Resistance to Antimicrobial Agents and Bacterial Invasion Are Caused by Synergistic Interactions in Multispecies Biofilms". Applied and Environmental Microbiology 72, n. 6 (giugno 2006): 3916–23. http://dx.doi.org/10.1128/aem.03022-05.

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Abstract (sommario):

ABSTRACT Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated from the surface of the marine alga Ulva australis, were screened for synergistic interactions within biofilms when present together in different combinations. Four isolates, Microbacterium phyllosphaerae, Shewanella japonica, Dokdonia donghaensis, and Acinetobacter lwoffii, were found to interact synergistically in biofilms formed in 96-well microtiter plates: biofilm biomass was observed to increase by >167% in biofilms formed by the four strains compared to biofilms composed of single strains. When exposed to the antibacterial agent hydrogen peroxide or tetracycline, the relative activity (exposed versus nonexposed biofilms) of the four-species biofilm was markedly higher than that in any of the single-species biofilms. Moreover, in biofilms established on glass surfaces in flow cells and subjected to invasion by the antibacterial protein-producing Pseudoalteromonas tunicata, the four-species biofilms resisted invasion to a greater extent than did the biofilms formed by the single species. Replacement of each strain by its cell-free culture supernatant suggested that synergy was dependent both on species-specific physical interactions between cells and on extracellular secreted factors or less specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms.

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23

Paramonova, Ekaterina, Bastiaan P. Krom, Henny C. van der Mei, Henk J. Busscher e Prashant K. Sharma. "Hyphal content determines the compression strength of Candida albicans biofilms". Microbiology 155, n. 6 (1 giugno 2009): 1997–2003. http://dx.doi.org/10.1099/mic.0.021568-0.

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Candida albicans is the most frequently isolated human fungal pathogen among species causing biofilm-related clinical infections. Mechanical properties of Candida biofilms have hitherto been given no attention, despite the fact that mechanical properties are important for selection of treatment or dispersal of biofilm organisms due to a bodily fluid flow. The aim of this study was to identify the factors that determine the compression strength of Candida biofilms. Biofilms of C. albicans wild-type parental strain Caf2-1, mutant strain Chk24 lacking Chk1p [known to be involved in regulation of morphogenesis (yeast-to-hyphae transition)] and gene-reconstructed strain Chk23 were evaluated for their resistance to compression, along with biofilms of Candida tropicalis GB 9/9 and Candida parapsilosis GB 2/8, derived from used voice prosthetic biofilms. Additionally, cell morphologies within the biofilm, cell-surface hydrophobicities and extracellular polymeric substance composition were determined. Our results suggest that the hyphae-to-yeast ratio influences the compression strength of C. albicans biofilms. Biofilms with a hyphal content >50 % possessed significantly higher compressive strength and were more difficult to destroy by vortexing and sonication than biofilms with a lower hyphal content. However, when the amount of extracellular DNA (eDNA) in biofilms of C. albicans Caf2-1 and Chk24 increased, biofilm strength declined, suggesting that eDNA may influence biofilm integrity adversely.

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24

Gobin, Maxime, Richard Proust, Stéphane Lack, Laura Duciel, Céline Des Courtils, Emmanuel Pauthe, Adeline Gand e Damien Seyer. "A Combination of the Natural Molecules Gallic Acid and Carvacrol Eradicates P. aeruginosa and S. aureus Mature Biofilms". International Journal of Molecular Sciences 23, n. 13 (27 giugno 2022): 7118. http://dx.doi.org/10.3390/ijms23137118.

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Abstract (sommario):

Wound infection, especially the development of bacterial biofilms, delays wound healing and is a major public health concern. Bacteria in biofilms are more tolerant to antimicrobial agents, and new treatments to eradicate mature biofilms are needed. Combining antimicrobial molecules with different mechanisms of action is an attractive strategy to tackle the heterogeneous nature of microbial communities in biofilms. This study focused on three molecules of natural origin: gallic acid (G), carvacrol (K) and curcumin (Q). Their abilities, individually or in combination, to eradicate biofilms were quantified on mono- and dual-species mature biofilms of Pseudomonas aeruginosa and Staphylococcus aureus, the strains most commonly found in infected wounds. G presented biofilm eradicating activity on P. aeruginosa, whereas K had biofilm eradicating activity on S. aureus and P. aeruginosa. Q had no potent biofilm eradicating activity. The combination of G and K increased the effects previously observed on P. aeruginosa biofilm and led to complete eradication of S. aureus biofilm. This combination was also efficient in eradicating a dual-species biofilm of S. aureus and P. aeruginosa. This work demonstrates that K and G used in combination have a strong and synergistic eradicating activity on both mono- and dual-species mature biofilms of S. aureus and P. aeruginosa and may therefore represent an efficient alternative for the treatment of biofilms in wounds.

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25

Kvist, Malin, Viktoria Hancock e Per Klemm. "Inactivation of Efflux Pumps Abolishes Bacterial Biofilm Formation". Applied and Environmental Microbiology 74, n. 23 (3 ottobre 2008): 7376–82. http://dx.doi.org/10.1128/aem.01310-08.

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Abstract (sommario):

ABSTRACT Bacterial biofilms cause numerous problems in health care and industry; notably, biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Bacteria rely on efflux pumps to get rid of toxic substances. We discovered that efflux pumps are highly active in bacterial biofilms, thus making efflux pumps attractive targets for antibiofilm measures. A number of efflux pump inhibitors (EPIs) are known. EPIs were shown to reduce biofilm formation, and in combination they could abolish biofilm formation completely. Also, EPIs were able to block the antibiotic tolerance of biofilms. The results of this feasibility study might pave the way for new treatments for biofilm-related infections and may be exploited for prevention of biofilms in general.

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26

Dranguet, Perrine, Vera I. Slaveykova e Séverine Le Faucheur. "Kinetics of mercury accumulation by freshwater biofilms". Environmental Chemistry 14, n. 7 (2017): 458. http://dx.doi.org/10.1071/en17073.

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Abstract (sommario):

Environmental contextMercury (Hg) is a major environmental contaminant due to its toxicity, accumulation and biomagnification along the food chain. We demonstrate that Hg accumulation by biofilms, one possible entry point for Hg into food webs, is rapid and depends on biofilm structure and composition. These findings have important implications for the understanding of Hg bioavailability and effects towards aquatic microorganisms. AbstractMercury contamination is of high concern due to its bioaccumulation, toxicity and biomagnification along the food chain. Biofilms can accumulate Hg and contribute to its incorporation in freshwater food webs. Nevertheless, the accumulation kinetics of Hg by biofilms is not well described and understood. The aim of the present study was thus to gain mechanistic understanding of Hg accumulation by biofilms. Kinetics of Hg uptake by biofilms of different ages (e.g. different compositions) was characterised by determining Hg contents in biofilms with and without a cysteine-washing step. Hg accumulation was rapid in both biofilms, with the uptake rate constant of the younger biofilm 10 times higher than that of the older biofilm. Moreover, accumulated Hg reached a plateau at 24h exposure in the younger biofilm, whereas it increased linearly in the older biofilm. The observed difference in Hg uptake by the studied biofilms is likely a result of the difference in biofilm thickness (and thus Hg diffusion inside the biofilm matrix) and microbial composition. These findings have important implications for the understanding of Hg bioavailability and effects towards aquatic microorganisms.

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27

Chavez-Dozal, Alba A., Livia Lown, Maximillian Jahng, Carla J. Walraven e Samuel A. Lee. "In VitroAnalysis of Finasteride Activity against Candida albicans Urinary Biofilm Formation and Filamentation". Antimicrobial Agents and Chemotherapy 58, n. 10 (21 luglio 2014): 5855–62. http://dx.doi.org/10.1128/aac.03137-14.

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Abstract (sommario):

ABSTRACTCandida albicansis the 3rd most common cause of catheter-associated urinary tract infections, with a strong propensity to form drug-resistant catheter-related biofilms. Due to the limited efficacy of available antifungals against biofilms, drug repurposing has been investigated in order to identify novel agents with activities against fungal biofilms. Finasteride is a 5-α-reductase inhibitor commonly used for the treatment of benign prostatic hyperplasia, with activity against human type II and III isoenzymes. We analyzed theCandidaGenome Database and identified aC. albicanshomolog of type III 5-α-reductase, Dfg10p, which shares 27% sequence identity and 41% similarity to the human type III 5-α-reductase. Thus, we investigated finasteride for activity againstC. albicansurinary biofilms, alone and in combination with amphotericin B or fluconazole. Finasteride alone was highly effective in the prevention ofC. albicansbiofilm formation at doses of ≥16 mg/liter and the treatment of preformed biofilms at doses of ≥128 mg/liter. In biofilm checkerboard analyses, finasteride exhibited synergistic activity in the prevention of biofilm formation in a combination of 4 mg/liter finasteride with 2 mg/liter fluconazole. Finasteride inhibited filamentation, thus suggesting a potential mechanism of action. These results indicate that finasteride alone is highly active in the prevention ofC. albicansurinary biofilmsin vitroand has synergistic activity in combination with fluconazole. Further investigation of the clinical utility of finasteride in the prevention of urinary candidiasis is warranted.

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28

Samrot, Antony V., Amira Abubakar Mohamed, Etel Faradjeva, Lee Si Jie, Chin Hooi Sze, Akasha Arif, Tan Chuan Sean et al. "Mechanisms and Impact of Biofilms and Targeting of Biofilms Using Bioactive Compounds—A Review". Medicina 57, n. 8 (18 agosto 2021): 839. http://dx.doi.org/10.3390/medicina57080839.

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Abstract (sommario):

Biofilms comprising aggregates of microorganisms or multicellular communities have been a major issue as they cause resistance against antimicrobial agents and biofouling. To date, numerous biofilm-forming microorganisms have been identified, which have been shown to result in major effects including biofouling and biofilm-related infections. Quorum sensing (which describes the cell communication within biofilms) plays a vital role in the regulation of biofilm formation and its virulence. As such, elucidating the various mechanisms responsible for biofilm resistance (including quorum sensing) will assist in developing strategies to inhibit and control the formation of biofilms in nature. Employing biological control measures (such as the use of bioactive compounds) in targeting biofilms is of great interest since they naturally possess antimicrobial activity among other favorable attributes and can also possibly act as potent antibiofilm agents. As an effort to re-establish the current notion and understanding of biofilms, the present review discuss the stages involved in biofilm formation, the factors contributing to its development, the effects of biofilms in various industries, and the use of various bioactive compounds and their strategies in biofilm inhibition.

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29

Sidrim, José JC, Crister J. Ocadaque, Bruno R. Amando, Glaucia M. de M Guedes, Cecília L. Costa, Raimunda SN Brilhante, Rossana de A Cordeiro, Marcos FG Rocha e Débora SCM Castelo-Branco. "Rhamnolipid enhances Burkholderia pseudomallei biofilm susceptibility, disassembly and production of virulence factors". Future Microbiology 15, n. 12 (agosto 2020): 1109–21. http://dx.doi.org/10.2217/fmb-2020-0010.

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Abstract (sommario):

Aim: This study evaluated the effect of the biosurfactant rhamnolipid on the antimicrobial susceptibility, biofilm growth dynamics and production of virulence factors by Burkholderia pseudomallei. Materials & methods: The effects of rhamnolipid on planktonic and biofilm growth and its interaction with antibacterial drugs were evaluated. Then, its effects on growing and mature biofilms and on protease and siderophore production were assessed. Results: Rhamnolipid did not inhibit B. pseudomallei growth, but significantly enhanced the activity of meropenem and amoxicillin-clavulanate against mature biofilms. Rhamnolipid significantly reduced the biomass of mature biofilms, significantly increased protease production by growing and mature biofilms and siderophore release by growing biofilms. Conclusion: Rhamnolipid enhances the antimicrobial activity against B. pseudomallei, assists biofilm disassembly and alters protease and siderophore production by bacterial biofilms.

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30

Wang, Chao, Lingzhan Miao, Jun Hou, Peifang Wang, Jin Qian e Shanshan Dai. "The effect of flow velocity on the distribution and composition of extracellular polymeric substances in biofilms and the detachment mechanism of biofilms". Water Science and Technology 69, n. 4 (13 dicembre 2013): 825–32. http://dx.doi.org/10.2166/wst.2013.785.

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Abstract (sommario):

Flume experiments were conducted to investigate the distribution and composition of extracellular polymeric substances (EPS) in biofilms and the detachment mechanism of biofilms grown under different flow velocity conditions. The results of biofilm growth kinetics showed that the growth trends were coincident with the logistic growth model. The growth kinetics parameters reached their maximum under intermediate velocity (IV) condition. Biofilms exhibited different profiles of EPS composition and distribution, depending on the flow conditions in which the biofilms were grown. The amounts of total polysaccharide and total protein in the thin biofilm (high velocity condition 2 – HV2) were both generally greater than those in the thick biofilm (IV). As compared to the heterogeneous distribution of EPS in the thick biofilms (IV), the EPS in the thin biofilms (HV2) exhibited more homogeneous distribution, and the bound EPS in the thin biofilms (HV2) were much greater than those in the thick biofilms (IV). From the detachment tests, an inverse relationship was observed between the proportion of detached biomass and the value of flow velocity during growth. Biofilms grown under higher velocities showed stronger cohesion than those grown under lower velocities. Therefore, water velocity during biofilm growth conditioned the distribution and composition of EPS, as well as its detachment characteristics under higher shear stress.

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Yu, T., C. de la Rosa e R. Lu. "Microsensor measurement of oxygen concentration in biofilms: from one dimension to three dimensions". Water Science and Technology 49, n. 11-12 (1 giugno 2004): 353–58. http://dx.doi.org/10.2166/wst.2004.0878.

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Abstract (sommario):

In this study, we measured oxygen concentration in biofilms in one dimension in field conditions and in three dimensions in laboratory conditions by using a robust oxygen microsensor in combination with an automation and data acquisition system. The biofilms were on the discs of rotating biological contactors treating domestic wastewater. The results of this study provide experimental evidence on oxygen distribution in wastewater biofilms and on biofilm structure. (1) The three dimensional measurements of oxygen concentration in biofilms revealed “pockets” of oxygen in deep sections of biofilms. In these isolated "pockets," located 600-760 mm from the biofilm surface, dissolved oxygen concentration was as high as 1 mg/L. This depth of oxygen diffusion is deeper than what was determined based on one dimensional measurements. (2) The heterogeneity of oxygen distribution was related to the surface structure of biofilms. The structure of the biofilm surface affected the diffusion boundary layer over the surface and, in turn, the oxygen diffusion and distribution inside biofilms. (3) Oxygen concentration in biofilms changed generally from a high degree of heterogeneity near the biofilm surface to a low degree of heterogeneity in deep sections of biofilms, indicating a cell-clusters-like structure near the surface and a more compact base layer close to the substratum.

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32

Xu, Tao, Yue Xiao, Hongchao Wang, Jinlin Zhu, Yuankun Lee, Jianxin Zhao, Wenwei Lu e Hao Zhang. "Characterization of Mixed-Species Biofilms Formed by Four Gut Microbiota". Microorganisms 10, n. 12 (25 novembre 2022): 2332. http://dx.doi.org/10.3390/microorganisms10122332.

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Abstract (sommario):

In natural settings, approximately 40–80% of bacteria exist as biofilms, most of which are mixed-species biofilms. Previous studies have typically focused on single- or dual-species biofilms. To expand the field of study on gut biofilms, we found a group of gut microbiota that can form biofilms well in vitro: Bifidobacterium longum subsp. infantis, Enterococcus faecalis, Bacteroides ovatus, and Lactobacillus gasseri. The increase in biomass and bio-volume of the mixed-species biofilm was confirmed via crystal violet staining, field emission scanning electron microscopy, and confocal laser scanning microscopy, revealing a strong synergistic relationship in these communities, with B. longum being the key biofilm-contributing species. This interaction may be related to changes in the cell number, biofilm-related genes, and metabolic activities. After quantifying the cell number using quantitative polymerase chain reaction, B. longum and L. gasseri were found to be the dominant flora in the mixed-species biofilm. In addition, this study analyzed biological properties of mixed-species biofilms, such as antibiotic resistance, cell metabolic activity, and concentration of water-insoluble polysaccharides. Compared with single-species biofilms, mixed-species biofilms had higher metabolic activity, more extracellular matrix, and greater antibiotic resistance. From these results, we can see that the formation of biofilms is a self-protection mechanism of gut microbiota, and the formation of mixed-species biofilms can greatly improve the survival rate of different strains. Finally, this study is a preliminary exploration of the biological characteristics of gut biofilms, and the molecular mechanisms underlying the formation of biofilms warrant further research.

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33

Izano, Era A., Matthew A. Amarante, William B. Kher e Jeffrey B. Kaplan. "Differential Roles of Poly-N-Acetylglucosamine Surface Polysaccharide and Extracellular DNA in Staphylococcus aureus and Staphylococcus epidermidis Biofilms". Applied and Environmental Microbiology 74, n. 2 (26 novembre 2007): 470–76. http://dx.doi.org/10.1128/aem.02073-07.

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Abstract (sommario):

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis are major human pathogens of increasing importance due to the dissemination of antibiotic-resistant strains. Evidence suggests that the ability to form matrix-encased biofilms contributes to the pathogenesis of S. aureus and S. epidermidis. In this study, we investigated the functions of two staphylococcal biofilm matrix polymers: poly-N-acetylglucosamine surface polysaccharide (PNAG) and extracellular DNA (ecDNA). We measured the ability of a PNAG-degrading enzyme (dispersin B) and DNase I to inhibit biofilm formation, detach preformed biofilms, and sensitize biofilms to killing by the cationic detergent cetylpyridinium chloride (CPC) in a 96-well microtiter plate assay. When added to growth medium, both dispersin B and DNase I inhibited biofilm formation by both S. aureus and S. epidermidis. Dispersin B detached preformed S. epidermidis biofilms but not S. aureus biofilms, whereas DNase I detached S. aureus biofilms but not S. epidermidis biofilms. Similarly, dispersin B sensitized S. epidermidis biofilms to CPC killing, whereas DNase I sensitized S. aureus biofilms to CPC killing. We concluded that PNAG and ecDNA play fundamentally different structural roles in S. aureus and S. epidermidis biofilms.

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34

Hu, Zhiqiang, Gabriela Hidalgo, Paul L. Houston, Anthony G. Hay, Michael L. Shuler, Héctor D. Abruña, William C. Ghiorse e Leonard W. Lion. "Determination of Spatial Distributions of Zinc and Active Biomass in Microbial Biofilms by Two-Photon Laser Scanning Microscopy". Applied and Environmental Microbiology 71, n. 7 (luglio 2005): 4014–21. http://dx.doi.org/10.1128/aem.71.7.4014-4021.2005.

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Abstract (sommario):

ABSTRACT The spatial distributions of zinc, a representative transition metal, and active biomass in bacterial biofilms were determined using two-photon laser scanning microscopy (2P-LSM). Application of 2P-LSM permits analysis of thicker biofilms than are amenable to observation with confocal laser scanning microscopy and also provides selective excitation of a smaller focal volume with greater depth localization. Thin Escherichia coli PHL628 biofilms were grown in a minimal mineral salts medium using pyruvate as the carbon and energy source under batch conditions, and thick biofilms were grown in Luria-Bertani medium using a continuous-flow drip system. The biofilms were visualized by 2P-LSM and shown to have heterogeneous structures with dispersed dense cell clusters, rough surfaces, and void spaces. Contrary to homogeneous biofilm model predictions that active biomass would be located predominantly in the outer regions of the biofilm and inactive or dead biomass (biomass debris) in the inner regions, significant active biomass fractions were observed at all depths in biofilms (up to 350 μm) using live/dead fluorescent stains. The active fractions were dependent on biofilm thickness and are attributed to the heterogeneous characteristics of biofilm structures. A zinc-binding fluorochrome (8-hydroxy-5-dimethylsulfoamidoquinoline) was synthesized and used to visualize the spatial location of added Zn within biofilms. Zn was distributed evenly in a thin (12 μm) biofilm but was located only at the surface of thick biofilms, penetrating less than 20 μm after 1 h of exposure. The relatively slow movement of Zn into deeper biofilm layers provides direct evidence in support of the concept that thick biofilms may confer resistance to toxic metal species by binding metals at the biofilm-bulk liquid interface, thereby retarding metal diffusion into the biofilm (G. M. Teitzel and M. R. Park, Appl. Environ. Microbiol. 69:2313-2320, 2003).

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35

Detusheva, E. V., P. V. Slukin e N. K. Fursova. "Molecular-genetic methods for studying microbial biofilms". Bacteriology 5, n. 2 (2020): 49–55. http://dx.doi.org/10.20953/2500-1027-2020-2-49-55.

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Abstract (sommario):

The review article contains information on the clinical significance of microbial biofilms and the main modern molecular genetic methods used to study microbial biofilms: comparative study of genome, transcriptome and proteome of planktonic cells and biofilms; genetic control of biofilm extracellular matrix production; analysis of the contribution of individual genes and gene clusters to the formation of the biofilm phenotype; identification of microorganism species in polymicrobial biofilms. Key words: microbial biofilms, molecular genetic methods, genome, transcriptome, proteome, microbial species identification

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36

Purevdorj, B., J. W. Costerton e P. Stoodley. "Influence of Hydrodynamics and Cell Signaling on the Structure and Behavior of Pseudomonas aeruginosa Biofilms". Applied and Environmental Microbiology 68, n. 9 (settembre 2002): 4457–64. http://dx.doi.org/10.1128/aem.68.9.4457-4464.2002.

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Abstract (sommario):

ABSTRACT Biofilms were grown from wild-type (WT) Pseudomonas aeruginosa PAO1 and the cell signaling lasI mutant PAO1-JP1 under laminar and turbulent flows to investigate the relative contributions of hydrodynamics and cell signaling for biofilm formation. Various biofilm morphological parameters were quantified using Image Structure Analyzer software. Multivariate analysis demonstrated that both cell signaling and hydrodynamics significantly (P < 0.000) influenced biofilm structure. In turbulent flow, both biofilms formed streamlined patches, which in some cases developed ripple-like wave structures which flowed downstream along the surface of the flow cell. In laminar flow, both biofilms formed monolayers interspersed with small circular microcolonies. Ripple-like structures also formed in four out of six WT biofilms, although their velocity was approximately 10 times less than that of those that formed in the turbulent flow cells. The movement of biofilm cell clusters over solid surfaces may have important clinical implications for the dissemination of biofilm subject to fluid shear, such as that found in catheters. The ability of the cell signaling mutant to form biofilms in high shear flow demonstrates that signaling mechanisms are not required for the formation of strongly adhered biofilms. Similarity between biofilm morphologies in WT and mutant biofilms suggests that the dilution of signal molecules by mass transfer effects in faster flowing systems mollifies the dramatic influence of signal molecules on biofilm structure reported in previous studies.

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37

Zhang, Qiuting, Jian Li, Japinder Nijjer, Haoran Lu, Mrityunjay Kothari, Ricard Alert, Tal Cohen e Jing Yan. "Morphogenesis and cell ordering in confined bacterial biofilms". Proceedings of the National Academy of Sciences 118, n. 31 (30 luglio 2021): e2107107118. http://dx.doi.org/10.1073/pnas.2107107118.

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Biofilms are aggregates of bacterial cells surrounded by an extracellular matrix. Much progress has been made in studying biofilm growth on solid substrates; however, little is known about the biophysical mechanisms underlying biofilm development in three-dimensional confined environments in which the biofilm-dwelling cells must push against and even damage the surrounding environment to proliferate. Here, combining single-cell imaging, mutagenesis, and rheological measurement, we reveal the key morphogenesis steps of Vibrio cholerae biofilms embedded in hydrogels as they grow by four orders of magnitude from their initial size. We show that the morphodynamics and cell ordering in embedded biofilms are fundamentally different from those of biofilms on flat surfaces. Treating embedded biofilms as inclusions growing in an elastic medium, we quantitatively show that the stiffness contrast between the biofilm and its environment determines biofilm morphology and internal architecture, selecting between spherical biofilms with no cell ordering and oblate ellipsoidal biofilms with high cell ordering. When embedded in stiff gels, cells self-organize into a bipolar structure that resembles the molecular ordering in nematic liquid crystal droplets. In vitro biomechanical analysis shows that cell ordering arises from stress transmission across the biofilm–environment interface, mediated by specific matrix components. Our imaging technique and theoretical approach are generalizable to other biofilm-forming species and potentially to biofilms embedded in mucus or host tissues as during infection. Our results open an avenue to understand how confined cell communities grow by means of a compromise between their inherent developmental program and the mechanical constraints imposed by the environment.

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Dayton, Hannah, Julie Kiss, Mian Wei, Shradha Chauhan, Emily LaMarre, William Cole Cornell, Chase J. Morgan et al. "Cellular arrangement impacts metabolic activity and antibiotic tolerance in Pseudomonas aeruginosa biofilms". PLOS Biology 22, n. 2 (1 febbraio 2024): e3002205. http://dx.doi.org/10.1371/journal.pbio.3002205.

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Cells must access resources to survive, and the anatomy of multicellular structures influences this access. In diverse multicellular eukaryotes, resources are provided by internal conduits that allow substances to travel more readily through tissue than they would via diffusion. Microbes growing in multicellular structures, called biofilms, are also affected by differential access to resources and we hypothesized that this is influenced by the physical arrangement of the cells. In this study, we examined the microanatomy of biofilms formed by the pathogenic bacterium Pseudomonas aeruginosa and discovered that clonal cells form striations that are packed lengthwise across most of a mature biofilm’s depth. We identified mutants, including those defective in pilus function and in O-antigen attachment, that show alterations to this lengthwise packing phenotype. Consistent with the notion that cellular arrangement affects access to resources within the biofilm, we found that while the wild type shows even distribution of tested substrates across depth, the mutants show accumulation of substrates at the biofilm boundaries. Furthermore, we found that altered cellular arrangement within biofilms affects the localization of metabolic activity, the survival of resident cells, and the susceptibility of subpopulations to antibiotic treatment. Our observations provide insight into cellular features that determine biofilm microanatomy, with consequences for physiological differentiation and drug sensitivity.

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Pandit, Santosh, Mina Fazilati, Karolina Gaska, Abderahmane Derouiche, Tiina Nypelö, Ivan Mijakovic e Roland Kádár. "The Exo-Polysaccharide Component of Extracellular Matrix is Essential for the Viscoelastic Properties of Bacillus subtilis Biofilms". International Journal of Molecular Sciences 21, n. 18 (15 settembre 2020): 6755. http://dx.doi.org/10.3390/ijms21186755.

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Bacteria are known to form biofilms on various surfaces. Biofilms are multicellular aggregates, held together by an extracellular matrix, which is composed of biological polymers. Three principal components of the biofilm matrix are exopolysaccharides (EPS), proteins, and nucleic acids. The biofilm matrix is essential for biofilms to remain organized under mechanical stress. Thanks to their polymeric nature, biofilms exhibit both elastic and viscous mechanical characteristics; therefore, an accurate mechanical description needs to take into account their viscoelastic nature. Their viscoelastic properties, including during their growth dynamics, are crucial for biofilm survival in many environments, particularly during infection processes. How changes in the composition of the biofilm matrix affect viscoelasticity has not been thoroughly investigated. In this study, we used interfacial rheology to study the contribution of the EPS component of the matrix to viscoelasticity of Bacillus subtilis biofilms. Two strategies were used to specifically deplete the EPS component of the biofilm matrix, namely (i) treatment with sub-lethal doses of vitamin C and (ii) seamless inactivation of the eps operon responsible for biosynthesis of the EPS. In both cases, the obtained results suggest that the EPS component of the matrix is essential for maintaining the viscoelastic properties of bacterial biofilms during their growth. If the EPS component of the matrix is depleted, the mechanical stability of biofilms is compromised and the biofilms become more susceptible to eradication by mechanical stress.

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Khalil, Maha A., Jamal A. Alorabi, Lamya M. Al-Otaibi, Sameh S. Ali e Sobhy E. Elsilk. "Antibiotic Resistance and Biofilm Formation in Enterococcus spp. Isolated from Urinary Tract Infections". Pathogens 12, n. 1 (25 dicembre 2022): 34. http://dx.doi.org/10.3390/pathogens12010034.

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Background: A urinary tract infection (UTI) resulting from multidrug-resistant (MDR) enterococci is a common disease with few therapeutic options. About 15% of urinary tract infections are caused by biofilm-producing Enterococcus spp. Therefore, the objective of this study was to identify the MDR enterococci associated with UTIs and assess their potential to produce biofilms. Methods: Thirty Enterococcus isolates were obtained from urine samples collected from UTI patients at King Abdulaziz Specialist Hospital in Taif, Saudi Arabia. The antimicrobial resistance profiles of the isolates were evaluated using disk diffusion techniques against 15 antimicrobial agents. Two techniques, Congo red agar (CRA) and a microtiter plate (MTP), were used to assess the potential of the isolates to produce biofilms. The enterococcal isolates were screened for biofilm-related genes, esp; ebpA; and ebpB, using the PCR method. Results: The molecular identification of the collected bacteria revealed the presence of 73.3% Enterococcus faecalis and 26.6% Enterococcus faecium. The antibiotic susceptibility test revealed that all the tested Enterococcus spp. were resistant to all antimicrobials except for linezolid and tigecycline. Additionally, by employing the CRA and MTP techniques, 76.6% and 100% of the Enterococcus isolates were able to generate biofilms, respectively. In terms of the association between the antibiotic resistance and biofilm’s formation, it was observed that isolates capable of creating strong biofilms were extremely resistant to most of the antibiotics tested. The obtained data showed that all the tested isolates had biofilm-encoding genes. Conclusions: Our research revealed that the biofilm-producing enterococci bacteria that causes urinary tract infections were resistant to antibiotics. Therefore, it is necessary to seek other pharmacological treatments if antibiotic medicine fails.

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Hamzah, Hasyrul, Triana Hertiani, Sylvia Utami Tunjung Pratiwi, Titik Nuryastuti e Yosi Bayu Murti. "The biofilm inhibition and eradication activity of curcumin againts polymicrobial biofilm". BIO Web of Conferences 28 (2020): 04001. http://dx.doi.org/10.1051/bioconf/20202804001.

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Curcumin is a polyphenol compound that is a member of the ginger family (Zingiberaceae), which has potential as an antibacterial, antifungal, and polymicrobial antibiofilm on the catheter. Still, its inhibitory activity and eradication of non-catheter polymicrobial antibiotics against S. aureus, P. aeruginosa, E. coli, and C. albicans have never been reported. The discovery of a candidate polymicrobial anti-biofilm drug is indispensable for overcoming infections associated with biofilms. This study aims to determine the inhibitory activity and eradication of curcumin on polymicrobial biofilms. Inhibition testing and eradication activity of polymicrobial biofilms were performed using the microtiter broth method. The effectiveness of curcumin on polymicrobial biofilms was analyzed using minimum biofilm inhibition concentration (MBIC50) and minimum biofilm eradication concentration (MBEC50). The mechanism of action of curcumin against polymicrobial biofilms is tested using scanning electron microscopy (SEM). Curcumin 1 % b/v gives biofilm inhibition activity in the mid-phase and maturation of 62.23 % ± 0.01, 59.43 % ± 0.01, and can eradicate polymicrobial biofilms by 55.79 % ± 0.01 and not much different with nystatin drug control activity. The results also provide evidence that curcumin can damage the extracellular polymeric matrix (EPS) polymicrobial biofilms of S. aureus, P. aeruginosa, E. coli, and C. albicans and damage the morphology of polymicrobial biofilms. Therefore, curcumin can be developed as a candidate for new antibiofilm drugs against polymicrobial biofilms S. aureus, P. aeruginosa, E. coli dan C albicabs.

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Nesse, Live L., Ane Mohr Osland e Lene K. Vestby. "The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections". Microorganisms 11, n. 3 (28 febbraio 2023): 608. http://dx.doi.org/10.3390/microorganisms11030608.

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Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.

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Hill, Walter R., Angela T. Bednarek e I. Lauren Larsen. "Cadmium sorption and toxicity in autotrophic biofilms". Canadian Journal of Fisheries and Aquatic Sciences 57, n. 3 (1 marzo 2000): 530–37. http://dx.doi.org/10.1139/f99-286.

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Autotrophic biofilms (periphyton) accumulate substantial quantities of metals from contaminated water. In this study, we measured the time course of biofilm cadmium sorption, examined the effects of current, biomass, and light on short-term cadmium sorption by biofilms, and tested the toxicity of cadmium to biofilm photosynthesis. The time course of cadmium sorption appeared to be a linear function of time over the 48-h measurement period. Biofilms in current [Formula: see text]2 cm·s-1 sorbed three to five times more cadmium than biofilms in still water. Cadmium sorbed after 4 h was 75% greater in high-biomass biofilm (2.5 mg dry mass·cm-2) than in low-biomass biofilm (0.5 mg dry mass·cm-2), but only in moving water. Light enhanced the sorption of cadmium 40% in one biofilm type. Cadmium toxicity to photo synthesis was evident after 24 h in thin biofilms exposed to initial cadmium concentrations [Formula: see text]10 μg·L-1; photosynthesis by thicker biofilms was not significantly impaired even at the highest concentration (100 μg·L-1). Variations in current, biofilm biomass, and light are likely to influence the movement of metals in flowing systems.

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Yang, Shanshan, Xinfei Li, Weihe Cang, Delun Mu, Shuaiqi Ji, Yuejia An, Rina Wu e Junrui Wu. "Biofilm tolerance, resistance and infections increasing threat of public health". Microbial Cell 10, n. 11 (6 novembre 2023): 233–47. http://dx.doi.org/10.15698/mic2023.11.807.

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Microbial biofilms can cause chronic infection. In the clinical setting, the biofilm-related infections usually persist and reoccur; the main reason is the increased antibiotic resistance of biofilms. Traditional antibiotic therapy is not effective and might increase the threat of antibiotic resistance to public health. Therefore, it is urgent to study the tolerance and resistance mechanism of biofilms to antibiotics and find effective therapies for biofilm-related infections. The tolerance mechanism and host reaction of biofilm to antibiotics are reviewed, and bacterial biofilm related diseases formed by human pathogens are discussed thoroughly. The review also explored the role of biofilms in the development of bacterial resistance mechanisms and proposed therapeutic intervention strategies for biofilm related diseases.

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Ogawa, Akiko, Keito Takakura, Katsuhiko Sano, Hideyuki Kanematsu, Takehiko Yamano, Toshikazu Saishin e Satoshi Terada. "Microbiome Analysis of Biofilms of Silver Nanoparticle-Dispersed Silane-Based Coated Carbon Steel Using a Next-Generation Sequencing Technique". Antibiotics 7, n. 4 (22 ottobre 2018): 91. http://dx.doi.org/10.3390/antibiotics7040091.

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Previously, we demonstrated that silver nanoparticle-dispersed silane-based coating could inhibit biofilm formation in conditions where seawater was used as a bacterial source and circulated in a closed laboratory biofilm reactor. However, it is still unclear whether the microbiome of a biofilm of silver nanoparticle-dispersed silane-based coating samples (Ag) differs from that of a biofilm of non-dispersed silane-based coating samples (Non-Ag). This study aimed to perform a microbiome analysis of the biofilms grown on the aforementioned coatings using a next-generation sequencing (NGS) technique. For this, a biofilm formation test was conducted by allowing seawater to flow through a closed laboratory biofilm reactor; subsequently, DNAs extracted from the biofilms of Ag and Non-Ag were used to prepare 16S rRNA amplicon libraries to analyze the microbiomes by NGS. Results of the operational taxonomy unit indicated that the biofilms of Non-Ag and Ag comprised one and no phyla of archaea, respectively, whereas Proteobacteria was the dominant phylum for both biofilms. Additionally, in both biofilms, Non-Ag and Ag, Marinomonas was the primary bacterial group involved in early stage biofilm formation, whereas Anaerospora was primarily involved in late-stage biofilm formation. These results indicate that silver nanoparticles will be unrelated to the bacterial composition of biofilms on the surface of silane-based coatings, while they control biofilm formation there.

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Ancy Chacko, Deepti, e Neha Dhaded. "Biofilm: An emergent form of bacterial life-a review". IP Indian Journal of Conservative and Endodontics 6, n. 2 (15 giugno 2021): 92–96. http://dx.doi.org/10.18231/j.ijce.2021.021.

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Biofilm formation is a method for bacteria to adapt for its survival, to put it another way, it act as a shield and prevents bacterial eradication. Microbial biofilms are one of the major reasons for progession of periradicular pathology. The article aims to concise and stratify the literature about, various factors that leads to biofilm formation their adaptation mechanisms, biofilms role in progression of peri-radicular infections, models developed to create biofilms, observation techniques of endodontic biofilms, and the effects of root canal irrigants and medicaments as well as lasers on endodontic biofilms.

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Agarwal, Harshita, e Gayathri Mahalingam. "BIOLOGICAL SYNTHESIS OF NANOPARTICLES FROM MEDICINAL PLANTS AND ITS USES IN INHIBITING BIOFILM FORMATION". Asian Journal of Pharmaceutical and Clinical Research 10, n. 5 (1 maggio 2017): 64. http://dx.doi.org/10.22159/ajpcr.2017.v10i5.17469.

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Pathogenic micro-organisms have become the main problem in today’s world. All microbes are getting resistant to antibiotics. This is due to theformation of biofilm layer above the micro-organisms. Learning the characteristics of biofilm can help us in treating the infectious disease induced via micro-organisms. They affect human’s life in some or the other way. For example, the plaque formed in our teeth that cause tooth decay is due to thebacterial biofilm. When micro-organisms stick to moist or wet surfaces, it produces glue-like, slimy contents which are known as biofilms. Biofilmsbelong to the sessile communities, communities in which organisms are considered as immobile. Biofilms are enclosed within a matrix, known asextracellular polymeric matrix, which are secreted by micro-organisms. Biofilms attached to the surfaces are affected by certain characteristics likethe growth medium, substratum to which it is attached and cellular surfaces. Each of these factors can either increase or decrease the hold of biofilmon the surfaces. With the help of biofilms, micro-organisms protect themselves from antibiotics and cause various infectious disease. Recent studies had proved medicinal plants to be effective in treating disease caused by microbes. Medicinal plants produce active compounds during secondarymetabolism which help in the treatment of infectious disease. The problem that arises with antibiotics is that they are unable to penetrate through thebiofilm. This problem is solved by converting antibiotics in nanoparticle size. Nanoparticles have high penetrating ability than the antibiotics. Theyhelp in controlling microbial growth by killing them.Keywords: Medicinal plants, Nanoparticles, Biofilm.

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Kozhyn, V., M. Kukhtyn, V. Horiuk, O. Vichko e Y. Kryzhanivsky. "The activity of the disinfectant “Enzidez” against bacteria in biofilms". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 23, n. 101 (5 aprile 2021): 67–74. http://dx.doi.org/10.32718/nvlvet10112.

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Currently, the pharmaceutical industry is constantly working on the creation of ideal disinfectants that would have a wide spectrum of antimicrobial action in minimal concentrations, did not result in the formation of stability in bacteria, were not toxic, not corrosive, not allergenic, cheap. The purpose of the work was to investigate the activity of the “Enzidesis” disidissance to influence microbial biofilms in vitro conditions for various sampling parameters. The density of microbial biofilms and the effects of disinfectants were determined on sterile stainless steel plates, which were placed in a Petri dish. For this purpose, biofilms were grown on plates, washed out biofilms from planktonic cells, acted as a disguise for a certain concentration and for a period of 5–30 minutes, fixed and painted biofilms and determined the optical density of the flushing solution from biofilms spectrometrically. It has been established that the disinfectant “Enzidesis” destroys the biofilms taken in the experiment of museum test cultures S. aureus, E. coli and P. aeruginosa. In particular, for the influence of the lowest concentration in experiment, 0.075 % optical density of washing solutions from S. aureus biofilmes decreased by 2.6 times, E. coli and P. aeruginosa biofilm in 2.9 times, respectively, comparing with biofilms after treatment with water. Under the actions of such a concentration of the “Enzidesis” means, the biofilm though significantly degraded, but they were still a medium density, more than 0.5 units. Increasing the concentration of a means of 0.075 % to 0.5 % contributed to the intensity of degradation of test-cultures, an average of 3.0 times (P < 0.05) and they became a weak density (0.24–0.20 s). Increasing the concentration of the “Enzidesis” means up to 1.0 % or more, did not significantly destroy the matrix of the biofilm of microorganisms, since the optical density of the washing solutions was as in control. In determining the influence of the temperature of the working solutions of the “Enzidosis” means on its film-building activity, it has been found that with an increase in the disinfection agent “Enzidesis” with +20 to +60 °С there is an increase in the degradation of the biofilm formed S. aureus, E. coli and P. aeruginosa. Dezilities can be effectively used in 0.5 % concentration at room temperature of solutions. When substantiating the exposure time of the “Enzidesis” exhibition time, it has been found that to remove the S. aureus, E. coli and P. aeruginosa 0.5 % means at a solution temperature of +20 ± 1 °C, it is necessary that the action time is from 15 to 30 minutes.

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Al-Fattani, Mohammed A., e L. Julia Douglas. "Penetration of Candida Biofilms by Antifungal Agents". Antimicrobial Agents and Chemotherapy 48, n. 9 (settembre 2004): 3291–97. http://dx.doi.org/10.1128/aac.48.9.3291-3297.2004.

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ABSTRACT A filter disk assay was used to investigate the penetration of antifungal agents through biofilms containing single and mixed-species biofilms containing Candida. Fluconazole permeated all single-species Candida biofilms more rapidly than flucytosine. The rates of diffusion of either drug through biofilms of three strains of Candida albicans were similar. However, the rates of drug diffusion through biofilms of C. glabrata or C. krusei were faster than those through biofilms of C. parapsilosis or C. tropicalis. In all cases, after 3 to 6 h the drug concentration at the distal edge of the biofilm was very high (many times the MIC). Nevertheless, drug penetration failed to produce complete killing of biofilm cells. These results indicate that poor antifungal penetration is not a major drug resistance mechanism for Candida biofilms. The abilities of flucytosine, fluconazole, amphotericin B, and voriconazole to penetrate mixed-species biofilms containing C. albicans and Staphylococcus epidermidis (a slime-producing wild-type strain, RP62A, and a slime-negative mutant, M7) were also investigated. All four antifungal agents diffused very slowly through these mixed-species biofilms. In most cases, diffusion was slower with biofilms containing S. epidermidis RP62A, but amphotericin B penetrated biofilms containing the M7 mutant more slowly. However, the drug concentrations reaching the distal edges of the biofilms always substantially exceeded the MIC. Thus, although the presence of bacteria and bacterial matrix material undoubtedly retarded the diffusion of the antifungal agents, poor penetration does not account for the drug resistance of Candida biofilm cells, even in these mixed-species biofilms.

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Ye, Zhang, Dina M. Silva, Daniela Traini, Paul Young, Shaokoon Cheng e Hui Xin Ong. "An adaptable microreactor to investigate the influence of interfaces on Pseudomonas aeruginosa biofilm growth". Applied Microbiology and Biotechnology 106, n. 3 (11 gennaio 2022): 1067–77. http://dx.doi.org/10.1007/s00253-021-11746-5.

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Abstract Biofilms are ubiquitous and notoriously difficult to eradicate and control, complicating human infections and industrial and agricultural biofouling. However, most of the study had used the biofilm model that attached to solid surface and developed in liquid submerged environments which generally have neglected the impact of interfaces. In our study, a reusable dual-chamber microreactor with interchangeable porous membranes was developed to establish multiple growth interfaces for biofilm culture and test. Protocol for culturing Pseudomonas aeruginosa (PAO1) on the air–liquid interface (ALI) and liquid–liquid interface (LLI) under static environmental conditions for 48 h was optimized using this novel device. This study shows that LLI model biofilms are more susceptible to physical disruption compared to ALI model biofilm. SEM images revealed a unique “dome-shaped” microcolonies morphological feature, which is more distinct on ALI biofilms than LLI. Furthermore, the study showed that ALI and LLI biofilms produced a similar amount of extracellular polymeric substances (EPS). As differences in biofilm structure and properties may lead to different outcomes when using the same eradication approaches, the antimicrobial effect of an antibiotic, ciprofloxacin (CIP), was chosen to test the susceptibility of a 48-h-old P. aeruginosa biofilms grown on ALI and LLI. Our results show that the minimum biofilm eradication concentration (MBEC) of 6-h CIP exposure for ALI and LLI biofilms is significantly different, which are 400 μg/mL and 200 μg/mL, respectively. These results highlight the importance of growth interface when developing more targeted biofilm management strategies, and our novel device provides a promising tool that enables manipulation of realistic biofilm growth. Key points • A novel dual-chamber microreactor device that enables the establishment of different interfaces for biofilm culture has been developed. • ALI model biofilms and LLI model biofilms show differences in resistance to physical disruption and antibiotic susceptibility.

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