Journal articles: 'Planktonic microbes'

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Cermeño, Pedro. "Marine planktonic microbes survived climatic instabilities in the past." Proceedings of the Royal Society B: Biological Sciences 279, no. 1728 (July 20, 2011): 474–79. http://dx.doi.org/10.1098/rspb.2011.1151.

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In the geological past, changes in climate and tectonic activity are thought to have spurred the tempo of evolutionary change among major taxonomic groups of plants and animals. However, the extent to which these historical contingencies increased the risk of extinction of microbial plankton species remains largely unknown. Here, I analyse fossil records of marine planktonic diatoms and calcareous nannoplankton over the past 65 million years from the world oceans and show that the probability of species' extinction is not correlated with secular changes in climatic instability. Further supporting these results, analyses of genera survivorship curves based on fossil data concurred with the predictions of a birth–death model that simulates the extinction of genera through time assuming stochastically constant rates of speciation and extinction. However, my results also show that these marine microbes responded to exceptional climatic contingencies in a manner that appears to have promoted net diversification. These results highlight the ability of marine planktonic microbes to survive climatic instabilities in the geological past, and point to different mechanisms underlying the processes of speciation and extinction in these micro-organisms.

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Li, William K. W., Robert A. Andersen, Dian J. Gifford, Lewis S. Incze, Jennifer L. Martin, Cynthia H. Pilskaln, Juliette N. Rooney-Varga, Michael E. Sieracki, William H. Wilson, and Nicholas H. Wolff. "Planktonic Microbes in the Gulf of Maine Area." PLoS ONE 6, no. 6 (June 15, 2011): e20981. http://dx.doi.org/10.1371/journal.pone.0020981.

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Khatun, Santona, Tomoya Iwata, Hisaya Kojima, Manabu Fukui, Takuya Aoki, Seito Mochizuki, Azusa Naito, Ai Kobayashi, and Ryo Uzawa. "Aerobic methane production by planktonic microbes in lakes." Science of The Total Environment 696 (December 2019): 133916. http://dx.doi.org/10.1016/j.scitotenv.2019.133916.

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Schiraldi, Alberto. "Growth and Decay of a Planktonic Microbial Culture." International Journal of Microbiology 2020 (January 24, 2020): 1–8. http://dx.doi.org/10.1155/2020/4186468.

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The paper shows that the phenomenological trends of both growth and decay of a microbial population in a given medium are easily reproducible with simple equations that allow gathering the experimental data (plate counts) related to different microbial species, in different mediums and even at different temperatures, in a single master plot. The guideline of the proposed approach is that microbes and surrounding medium form a system where they affect each other and that the so-called “growth curve” is just the phenomenological appearance of such interaction. The whole system (cells and medium) changes following a definite pathway described as the evolution of a “virtual” microbial population in planktonic conditions. The proposed equations come from the assumption of a duplication mechanism with a variable generation time for the growth and of an exponential-like decline with a linear increase of the rate for the decay. The intermediate phase between growth and decay is a time span during which growth and death counterbalance each other and age differences within the virtual cell population tend to level off. The proposed approach does not provide an a priori description of this phase but allows the fit of the whole evolution trend of a microbial culture whenever the experimental data are available. Deviations of such a trend concern microbes able to form spores, modify their metabolism, or express phenotypic heterogeneity, to counterbalance adverse medium conditions.

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Robertson, Emma J., and Arturo Casadevall. "Antibody-Mediated Immobilization of Cryptococcus neoformans Promotes Biofilm Formation." Applied and Environmental Microbiology 75, no. 8 (February 27, 2009): 2528–33. http://dx.doi.org/10.1128/aem.02846-08.

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ABSTRACT Most microbes, including the fungal pathogen Cryptococcus neoformans, can grow as biofilms. Biofilms confer upon microbes a range of characteristics, including an ability to colonize materials such as shunts and catheters and increased resistance to antibiotics. Here, we provide evidence that coating surfaces with a monoclonal antibody to glucuronoxylomannan, the major component of the fungal capsular polysaccharide, immobilizes cryptococcal cells to a surface support and, subsequently, promotes biofilm formation. We used time-lapse microscopy to visualize the growth of cryptococcal biofilms, generating the first movies of fungal biofilm growth. We show that when fungal cells are immobilized using surface-attached specific antibody to the capsule, the initial stages of biofilm formation are significantly faster than those on surfaces with no antibody coating or surfaces coated with unspecific monoclonal antibody. Time-lapse microscopy revealed that biofilm growth was a dynamic process in which cells shuffled position during budding and was accompanied by emergence of planktonic variant cells that left the attached biofilm community. The planktonic variant cells exhibited mobility, presumably by Brownian motion. Our results indicate that microbial immobilization by antibody capture hastens biofilm formation and suggest that antibody coating of medical devices with immunoglobulins must exclude binding to common pathogenic microbes and the possibility that this effect could be exploited in industrial microbiology.

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Sherr, Evelyn B., and Barry F. Sherr. "Planktonic microbes: Tiny cells at the base of the ocean's food webs." Trends in Ecology & Evolution 6, no. 2 (February 1991): 50–54. http://dx.doi.org/10.1016/0169-5347(91)90122-e.

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Asma, Syeda Tasmia, Kálmán Imre, Adriana Morar, Mirela Imre, Ulas Acaroz, Syed Rizwan Ali Shah, Syed Zajif Hussain, et al. "Natural Strategies as Potential Weapons against Bacterial Biofilms." Life 12, no. 10 (October 17, 2022): 1618. http://dx.doi.org/10.3390/life12101618.

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Microbial biofilm is an aggregation of microbial species that are either attached to surfaces or organized into an extracellular matrix. Microbes in the form of biofilms are highly resistant to several antimicrobials compared to planktonic microbial cells. Their resistance developing ability is one of the major root causes of antibiotic resistance in health sectors. Therefore, effective antibiofilm compounds are required to treat biofilm-associated health issues. The awareness of biofilm properties, formation, and resistance mechanisms facilitate researchers to design and develop combating strategies. This review highlights biofilm formation, composition, major stability parameters, resistance mechanisms, pathogenicity, combating strategies, and effective biofilm-controlling compounds. The naturally derived products, particularly plants, have demonstrated significant medicinal properties, producing them a practical approach for controlling biofilm-producing microbes. Despite providing effective antibiofilm activities, the plant-derived antimicrobial compounds may face the limitations of less bioavailability and low concentration of bioactive molecules. The microbes-derived and the phytonanotechnology-based antibiofilm compounds are emerging as an effective approach to inhibit and eliminate the biofilm-producing microbes.

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Villa Martín, Paula, Aleš Buček, Thomas Bourguignon, and Simone Pigolotti. "Ocean currents promote rare species diversity in protists." Science Advances 6, no. 29 (July 2020): eaaz9037. http://dx.doi.org/10.1126/sciadv.aaz9037.

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Oceans host communities of plankton composed of relatively few abundant species and many rare species. The number of rare protist species in these communities, as estimated in metagenomic studies, decays as a steep power law of their abundance. The ecological factors at the origin of this pattern remain elusive. We propose that chaotic advection by oceanic currents affects biodiversity patterns of rare species. To test this hypothesis, we introduce a spatially explicit coalescence model that reconstructs the species diversity of a sample of water. Our model predicts, in the presence of chaotic advection, a steeper power law decay of the species abundance distribution and a steeper increase of the number of observed species with sample size. A comparison of metagenomic studies of planktonic protist communities in oceans and in lakes quantitatively confirms our prediction. Our results support that oceanic currents positively affect the diversity of rare aquatic microbes.

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Badica, P., N. D. Batalu, M. C. Chifiriuc, M. Burdusel, M. A. Grigoroscuta, G. Aldica, I. Pasuk, et al. "MgB2 powders and bioevaluation of their interaction with planktonic microbes, biofilms, and tumor cells." Journal of Materials Research and Technology 12 (May 2021): 2168–84. http://dx.doi.org/10.1016/j.jmrt.2021.04.003.

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Bester, Elanna, Elizabeth A. Edwards, and Gideon M. Wolfaardt. "Planktonic cell yield is linked to biofilm development." Canadian Journal of Microbiology 55, no. 10 (October 2009): 1195–206. http://dx.doi.org/10.1139/w09-075.

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We report on the ability of surface-associated microbes to produce and release single planktonic cells to the bulk liquid as early as 6 h after attachment, with pure culture and mixed-species biofilms yielding up to ~1 × 106 cells/cm2 of attachment area per hour to the effluent after 24 h. Planktonic cell production typically increased as the biofilm developed and levelled off after the biofilm reached steady-state dimensions. Microscopic observations of continuous-flow cultured biofilms revealed independent cell movement within the biofilm microenvironment compared with flow-dependent movement of mostly single cells in the bulk-liquid phase. These results indicate that the prevailing concept of detachment occurring only after the biofilm has matured is incomplete. Instead, we show that biofilms yield cells to the environment soon after initial surface contact; the extent of this yield is dependent on biofilm development, which in turn is influenced by environmental parameters such as bulk-liquid flow rates and nutrient availability. The observation that biofilms yield significant numbers of cells throughout development should lead to a greater understanding of pathogen dissemination, biofouling of products or facilities, and the role that biofilms play in microbial proliferation in the environment.

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Ayukai, T. "Retention of phytoplankton and planktonic microbes on coral reefs within the Great Barrier Reef, Australia." Coral Reefs 14, no. 3 (September 1995): 141–47. http://dx.doi.org/10.1007/bf00367231.

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Aylward, Frank O., John M. Eppley, Jason M. Smith, Francisco P. Chavez, Christopher A. Scholin, and Edward F. DeLong. "Microbial community transcriptional networks are conserved in three domains at ocean basin scales." Proceedings of the National Academy of Sciences 112, no. 17 (March 9, 2015): 5443–48. http://dx.doi.org/10.1073/pnas.1502883112.

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Planktonic microbial communities in the ocean are typically dominated by several cosmopolitan clades ofBacteria,Archaea, andEukaryacharacterized by their ribosomal RNA gene phylogenies and genomic features. Although the environments these communities inhabit range from coastal to open ocean waters, how the biological dynamics vary between such disparate habitats is not well known. To gain insight into the differential activities of microbial populations inhabiting different oceanic provinces we compared the daily metatranscriptome profiles of related microbial populations inhabiting surface waters of both a coastal California upwelling region (CC) as well as the oligotrophic North Pacific Subtropical Gyre (NPSG). Transcriptional networks revealed that the dominant photoautotrophic microbes in each environment (Ostreococcusin CC,Prochlorococcusin NPSG) were central determinants of overall community transcriptome dynamics. Furthermore, heterotrophic bacterial clades common to both ecosystems (SAR11, SAR116, SAR86, SAR406, andRoseobacter) displayed conserved, genome-wide inter- and intrataxon transcriptional patterns and diel cycles. Populations of SAR11 and SAR86 clades in particular exhibited tightly coordinated transcriptional patterns in both coastal and pelagic ecosystems, suggesting that specific biological interactions between these groups are widespread in nature. Our results identify common diurnally oscillating behaviors among diverse planktonic microbial species regardless of habitat, suggesting that highly conserved temporally phased biotic interactions are ubiquitous among planktonic microbial communities worldwide.

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Folwell, Benjamin D., Terry J. McGenity, and Corinne Whitby. "Biofilm and Planktonic Bacterial and Fungal Communities Transforming High-Molecular-Weight Polycyclic Aromatic Hydrocarbons." Applied and Environmental Microbiology 82, no. 8 (February 5, 2016): 2288–99. http://dx.doi.org/10.1128/aem.03713-15.

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ABSTRACTHigh-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs) are natural components of fossil fuels that are carcinogenic and persistent in the environment, particularly in oil sands process-affected water (OSPW). Their hydrophobicity and tendency to adsorb to organic matter result in low bioavailability and high recalcitrance to degradation. Despite the importance of microbes for environmental remediation, little is known about those involved in HMW-PAH transformations. Here, we investigated the transformation of HMW-PAHs using samples of OSPW and compared the bacterial and fungal community compositions attached to hydrophobic filters and in suspension. It was anticipated that the hydrophobic filters with sorbed HMW-PAHs would select for microbes that specialize in adhesion. Over 33 days, more pyrene was removed (75% ± 11.7%) than the five-ring PAHs benzo[a]pyrene (44% ± 13.6%) and benzo[b]fluoranthene (41% ± 12.6%). For both bacteria and fungi, the addition of PAHs led to a shift in community composition, but thereafter the major factor determining the fungal community composition was whether it was in the planktonic phase or attached to filters. In contrast, the major determinant of the bacterial community composition was the nature of the PAH serving as the carbon source. The main bacteria enriched by HMW-PAHs werePseudomonas,Bacillus, andMicrobacteriumspecies. This report demonstrates that OSPW harbors microbial communities with the capacity to transform HMW-PAHs. Furthermore, the provision of suitable surfaces that encourage PAH sorption and microbial adhesion select for different fungal and bacterial species with the potential for HMW-PAH degradation.

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Santoro, A. E., M. Kellom, and S. M. Laperriere. "Contributions of single-cell genomics to our understanding of planktonic marine archaea." Philosophical Transactions of the Royal Society B: Biological Sciences 374, no. 1786 (October 7, 2019): 20190096. http://dx.doi.org/10.1098/rstb.2019.0096.

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Single-cell genomics has transformed many fields of biology, marine microbiology included. Here, we consider the impact of single-cell genomics on a specific group of marine microbes—the planktonic marine archaea. Despite single-cell enabled discoveries of novel metabolic function in the marine thaumarchaea, population-level investigations are hindered by an overall lower than expected recovery of thaumarchaea in single-cell studies. Metagenome-assembled genomes have so far been a more useful method for accessing genome-resolved insights into the Marine Group II euryarchaea. Future progress in the application of single-cell genomics to archaeal biology in the ocean would benefit from more targeted sorting approaches, and a more systematic investigation of potential biases against archaea in single-cell workflows including cell lysis, genome amplification and genome screening. This article is part of a discussion meeting issue ‘Single cell ecology’.

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Martinez, Luis R., and Arturo Casadevall. "Cryptococcus neoformans Cells in Biofilms Are Less Susceptible than Planktonic Cells to Antimicrobial Molecules Produced by the Innate Immune System." Infection and Immunity 74, no. 11 (November 2006): 6118–23. http://dx.doi.org/10.1128/iai.00995-06.

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ABSTRACT The human pathogenic fungus Cryptococcus neoformans can form biofilms on polystyrene plates and medical devices in a process that requires capsular polysaccharide release. Although biofilms are known to be less susceptible to antimicrobial drugs, little is known about their susceptibility to antimicrobial molecules produced by the innate immune system. In this study, we investigated the susceptibility of C. neoformans cells in biofilm and planktonic states to oxidative and nonoxidative antimicrobial molecules produced by phagocytic cells. The effects of various immune effector molecules on the fungal mass, metabolic activity, and architecture of C. neoformans biofilms were measured by colony counts, 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide reduction, and confocal microscopy, respectively. Biofilms were more resistant than planktonic cells to oxidative stress but remained vulnerable to cationic antimicrobial peptides. However, melanized biofilms were significantly less susceptible to antimicrobial peptides than nonmelanized biofilms. These results suggest that the biofilm phenotype increases resistance against host immune mechanisms, a phenomenon that could contribute to the ability of biofilm-forming microbes to establish persistent infections.

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Salcher, MM, and K. Šimek. "Isolation and cultivation of planktonic freshwater microbes is essential for a comprehensive understanding of their ecology." Aquatic Microbial Ecology 77, no. 3 (October 6, 2016): 183–96. http://dx.doi.org/10.3354/ame01796.

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Shah, Chirag B., Marc W. Mittelman, J. W. Costerton, Stephen Parenteau, Michael Pelak, Richard Arsenault, and Leonard A. Mermel. "Antimicrobial Activity of a Novel Catheter Lock Solution." Antimicrobial Agents and Chemotherapy 46, no. 6 (June 2002): 1674–79. http://dx.doi.org/10.1128/aac.46.6.1674-1679.2002.

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ABSTRACT Intravascular catheter-associated bloodstream infections significantly increase rates of morbidity and hospital costs. Microbial colonization and development of biofilms, which are known to be recalcitrant to antibiotic therapy, often lead to the loss of otherwise patent vascular access systems. We evaluated a new taurolidine- and citrate-based catheter lock solution (Neutrolin; Biolink Corporation, Norwell, Mass.) for its activity against planktonic microbes, antimicrobial activity in a catheter model, and biofilm eradication activity. In studies of planktonic microbes, after 24 h of contact, 675 mg of taurolidine-citrate solution per liter caused >99% reductions in the initial counts of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Entercoccus faecalis. A solution of 13,500 mg/liter was cidal for Candida albicans. Ports and attached catheters inoculated with 50 to 600 CFU of these bloodstream isolates per ml were locked with heparin or the taurolidine-citrate solution. After 72 h, there was no growth in the taurolidine-citrate-treated devices but the heparin-treated devices exhibited growth in the range of 6 × 102 to 5 × 106 CFU/ml. Biofilms were developed on silicone disks in modified Robbins devices with broth containing 6% serum (initial counts, 106 to 108 CFU/cm2). The axenic biofilms were treated for 24 h with taurolidine-citrate or heparin. Taurolidine-citrate exposure resulted in a median reduction of 4.8 logs, whereas heparin treatment resulted in a median reduction of 1.7 logs (P < 0.01). No significant differences in the effects of the two treatments against P. aeruginosa and C. albicans were observed. These findings suggest that taurolidine-citrate is a promising combination agent for the prevention and treatment of intravascular catheter-related infections.

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Fitzgerald, Shane, Ciara Furlong, Linda Holland, and Aoife Morrin. "Multi-Strain and -Species Investigation of Volatile Metabolites Emitted from Planktonic and Biofilm Candida Cultures." Metabolites 12, no. 5 (May 11, 2022): 432. http://dx.doi.org/10.3390/metabo12050432.

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Candida parapsiliosis is a prevalent neonatal pathogen that attains its virulence through its strain-specific ability to form biofilms. The use of volatilomics, the profiling of volatile metabolites from microbes is a non-invasive, simple way to identify and classify microbes; it has shown great potential for pathogen identification. Although C. parapsiliosis is one of the most common clinical fungal pathogens, its volatilome has never been characterised. In this study, planktonic volatilomes of ten clinical strains of C. parapsilosis were analysed, along with a single strain of Candida albicans. Headspace-solid-phase microextraction coupled with gas chromatography-mass spectrometry were employed to analyse the samples. Species-, strain-, and media- influences on the fungal volatilomes were investigated. Twenty-four unique metabolites from the examined Candida spp. (22 from C. albicans; 18 from C. parapsilosis) were included in this study. Chemical classes detected across the samples included alcohols, fatty acid esters, acetates, thiols, sesquiterpenes, and nitrogen-containing compounds. C. albicans volatilomes were most clearly discriminated from C. parapsilosis based on the detection of unique sesquiterpene compounds. The effect of biofilm formation on the C. parapsilosis volatilomes was investigated for the first time by comparing volatilomes of a biofilm-positive strain and a biofilm-negative strain over time (0–48 h) using a novel sampling approach. Volatilomic shifts in the profiles of alcohols, ketones, acids, and acetates were observed specifically in the biofilm-forming samples and attributed to biofilm maturation. This study highlights species-specificity of Candida volatilomes, and also marks the clinical potential for volatilomics for non-invasively detecting fungal pathogens. Additionally, the range of biofilm-specificity across microbial volatilomes is potentially far-reaching, and therefore characterising these volatilomic changes in pathogenic fungal and bacterial biofilms could lead to novel opportunities for detecting severe infections early.

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Lopes, Susana P., Nuno F. Azevedo, and Maria O. Pereira. "Emergent Bacteria in Cystic Fibrosis:In VitroBiofilm Formation and Resilience under Variable Oxygen Conditions." BioMed Research International 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/678301.

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Concurrent to conventional bacterial pathogens, unusual microbes are emerging from cystic fibrosis (CF) airways. Nonetheless, little is known about the contribution of these newly microbes to the resilience of CF-associated biofilms, particularly under variable-oxygen concentrations that are known to occurin vivoin the mucus of CF patients. Two CF-emergent bacterial species,Inquilinus limosusandDolosigranulum pigrum, and the major pathogenPseudomonas aeruginosawere studied in terms of biofilm development and antibiotic susceptibilities underin vitroatmospheres with different oxygen availabilities. All species were able to developin vitrobiofilms under different oxygen-available environments, withD. pigrumaccumulating high amounts of biomass and respiratory activities. When established, biofilms were of difficult eradication, with antibiotics losing their effectiveness in comparison with the corresponding planktonic populations. Surprisingly, biofilms of each emergent organism displayed multidrug resistance under aerobic environments, enduring even in low-oxygen atmospheres. This study suggests a potential prospect on the impact of nonconventional organismsI. limosusandD. pigrumon CF lung infections, demonstrating capacity to adapt to biofilm mode of life under restricted-oxygen atmospheres resembling CF airways, which may ultimately endanger the efficacy of currently used antibiotic regimens.

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Fudulu, Alina, Rodica Olar, Cătălin Maxim, Gina Vasile Scăeţeanu, Coralia Bleotu, Lilia Matei, Mariana Carmen Chifiriuc, and Mihaela Badea. "New Cobalt (II) Complexes with Imidazole Derivatives: Antimicrobial Efficiency against Planktonic and Adherent Microbes and In Vitro Cytotoxicity Features." Molecules 26, no. 1 (December 24, 2020): 55. http://dx.doi.org/10.3390/molecules26010055.

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Three novel Co(II) complexes of the type [Co(C4H5O2)2L2] (where C4H5O2 is methacrylate anion; L = C3H4N2 (imidazole; HIm) (1), C4H6N2 (2-methylimidazole; 2-MeIm) (2), C5H8N2 (2-ethylimidazole; 2-EtIm) (3)) have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopic techniques, thermal analysis and single crystal X-ray diffraction. X-ray crystallography revealed for complexes (1) and (2) distorted trigonal bipyramid stereochemistry for Co(II), meanwhile for complex (3) evidenced that the unit cell comprises three molecular units with interesting structural features. In each unit, both stereochemistry adopted by metallic ion and coordination modes of carboxylate anions are different. The screening of antimicrobial activity revealed that Candida albicans planktonic cells were the most susceptible, with minimal inhibitory concentration (MIC) values of 7.8 μg/mL for complexes (1) and (2) and 15.6 μg/mL for complex (3). Complexes (1) and (2) proved to be more active than complex (3) against the tested bacterial strains, both in planktonic and biofilm growth state, with MIC and minimal biofilm eradication concentration (MBEC) values ranging from 15.6 to 62.5 μg/mL, the best antibacterial effects being noticed against Staphylococcus aureus and Pseudomonas aeruginosa. Remarkably, the MBEC values obtained for the four tested bacterial strains were either identical or even lower than the MIC ones. The cytotoxicity assay indicated that the tested complexes affected the cellular cycle of HeLa, HCT-8, and MG63 cells, probably by inhibiting the expression of vimentin and transient receptor potential canonical 1 (TRPC1). The obtained biological results recommend these complexes as potential candidates for the development of novel anti-biofilm agents.

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Kvam, Erik, Brian Davis, Frank Mondello, and Allen L. Garner. "Nonthermal Atmospheric Plasma Rapidly Disinfects Multidrug-Resistant Microbes by Inducing Cell Surface Damage." Antimicrobial Agents and Chemotherapy 56, no. 4 (January 9, 2012): 2028–36. http://dx.doi.org/10.1128/aac.05642-11.

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ABSTRACTPlasma, a unique state of matter with properties similar to those of ionized gas, is an effective biological disinfectant. However, the mechanism through which nonthermal or “cold” plasma inactivates microbes on surfaces is poorly understood, due in part to challenges associated with processing and analyzing live cells on surfaces rather than in aqueous solution. Here, we employ membrane adsorption techniques to visualize the cellular effects of plasma on representative clinical isolates of drug-resistant microbes. Through direct fluorescent imaging, we demonstrate that plasma rapidly inactivates planktonic cultures, with >5 log10kill in 30 s by damaging the cell surface in a time-dependent manner, resulting in a loss of membrane integrity, leakage of intracellular components (nucleic acid, protein, ATP), and ultimately focal dissolution of the cell surface with longer exposure time. This occurred with similar kinetic rates among methicillin-resistantStaphylococcus aureus(MRSA),Pseudomonas aeruginosa, andCandida albicans. We observed no correlative evidence that plasma induced widespread genomic damage or oxidative protein modification prior to the onset of membrane damage. Consistent with the notion that plasma is superficial, plasma-mediated sterilization was dramatically reduced when microbial cells were enveloped in aqueous buffer prior to treatment. These results support the use of nonthermal plasmas for disinfecting multidrug-resistant microbes in environmental settings and substantiate ongoing clinical applications for plasma devices.

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Rachik, Sara, Urania Christaki, Luen Luen Li, Savvas Genitsaris, Elsa Breton, and Sébastien Monchy. "Diversity and potential activity patterns of planktonic eukaryotic microbes in a mesoeutrophic coastal area (eastern English Channel)." PLOS ONE 13, no. 5 (May 10, 2018): e0196987. http://dx.doi.org/10.1371/journal.pone.0196987.

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Henry-Stanley, Michelle J., Donavon J. Hess, and Carol L. Wells. "Aminoglycoside inhibition of Staphylococcus aureus biofilm formation is nutrient dependent." Journal of Medical Microbiology 63, no. 6 (June 1, 2014): 861–69. http://dx.doi.org/10.1099/jmm.0.068130-0.

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Biofilms represent microbial communities, encased in a self-produced matrix or extracellular polymeric substance. Microbial biofilms are likely responsible for a large proportion of clinically significant infections and the multicellular nature of biofilm existence has been repeatedly associated with antibiotic resistance. Classical in vitro antibiotic-susceptibility testing utilizes artificial growth media and planktonic microbes, but this method may not account for the variability inherent in environments subject to biofilm growth in vivo. Experiments were designed to test the hypothesis that nutrient concentration can modulate the antibiotic susceptibility of Staphylococcus aureus biofilms. Developing S. aureus biofilms initiated on surgical sutures, and in selected experiments planktonic cultures, were incubated for 16 h in 66 % tryptic soy broth, 0.2 % glucose (1× TSBg), supplemented with bactericidal concentrations of gentamicin, streptomycin, ampicillin or vancomycin. In parallel experiments, antibiotics were added to growth medium diluted one-third (1/3× TSBg) or concentrated threefold (3× TSBg). Following incubation, viable bacteria were enumerated from planktonic cultures or suture sonicates, and biofilm biomass was assayed using spectrophotometry. Interestingly, bactericidal concentrations of gentamicin (5 µg gentamicin ml−1) and streptomycin (32 µg streptomycin ml−1) inhibited biofilm formation in samples incubated in 1/3× or 1× TSBg, but not in samples incubated in 3× TSBg. The nutrient dependence of aminoglycoside susceptibility is not only associated with biofilm formation, as planktonic cultures incubated in 3× TSBg in the presence of gentamicin also showed antibiotic resistance. These findings appeared specific for aminoglycosides because biofilm formation was inhibited in all three growth media supplemented with bactericidal concentrations of the cell wall-active antibiotics, ampicillin and vancomycin. Additional experiments showed that the ability of 3× TSBg to overcome the antibacterial effects of gentamicin was associated with decreased uptake of gentamicin by S. aureus. Uptake is known to be decreased at low pH, and the kinetic change in pH of growth medium from biofilms incubated in 5 µg gentamicin ml−1 in the presence of 3× TSBg was decreased when compared with pH determinations from biofilms formed in 1/3× or 1× TSBg. These studies underscore the importance of environmental factors, including nutrient concentration and pH, on the antibiotic susceptibility of S. aureus planktonic and biofilm bacteria.

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Bastaraud, Alexandra, Philippe Cecchi, Pascal Handschumacher, Mathias Altmann, and Ronan Jambou. "Urbanization and Waterborne Pathogen Emergence in Low-Income Countries: Where and How to Conduct Surveys?" International Journal of Environmental Research and Public Health 17, no. 2 (January 11, 2020): 480. http://dx.doi.org/10.3390/ijerph17020480.

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A major forthcoming sanitary issue concerns the apparition and spreading of drug-resistant microorganisms, potentially threatening millions of humans. In low-income countries, polluted urban runoff and open sewage channels are major sources of microbes. These microbes join natural microbial communities in aquatic ecosystems already impacted by various chemicals, including antibiotics. These composite microbial communities must adapt to survive in such hostile conditions, sometimes promoting the selection of antibiotic-resistant microbial strains by gene transfer. The low probability of exchanges between planktonic microorganisms within the water column may be significantly improved if their contact was facilitated by particular meeting places. This could be specifically the case within biofilms that develop on the surface of the myriads of floating macroplastics increasingly polluting urban tropical surface waters. Moreover, as uncultivable bacterial strains could be involved, analyses of the microbial communities in their whole have to be performed. This means that new-omic technologies must be routinely implemented in low- and middle-income countries to detect the appearance of resistance genes in microbial ecosystems, especially when considering the new ‘plastic context.’ We summarize the related current knowledge in this short review paper to anticipate new strategies for monitoring and surveying microbial communities.

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Gutiérrez, MH, J. Vera, B. Srain, RA Quiñones, L. Wörmer, KU Hinrichs, and S. Pantoja-Gutiérrez. "Biochemical fingerprints of marine fungi: implications for trophic and biogeochemical studies." Aquatic Microbial Ecology 84 (March 26, 2020): 75–90. http://dx.doi.org/10.3354/ame01927.

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Fungi are ubiquitous in the marine environment, but their role in carbon and nitrogen cycling in the ocean, and in particular the quantitative significance of fungal biomass to ocean biogeochemistry, has not yet been assessed. Determination of the biochemical and stable isotope composition of marine fungi can provide a basis for identifying fungal patterns in relation to other microbes and detritus, and thus allow evaluation of their contribution to the transformation of marine organic matter. We characterized the biochemical composition of 13 fungal strains isolated from distinct marine environments in the eastern South Pacific Ocean off Chile. Proteins accounted for 3 to 21% of mycelial dry weight, with notably high levels of the essential amino acids histidine, threonine, valine, lysine and leucine, as well as polyunsaturated fatty acids, ergosterol, and phosphatidylcholine. Elemental composition and energetic content of these marine-derived fungi were within the range reported for bacteria, phytoplankton, zooplankton and other metazoans from aquatic environments, but a distinct pattern of lipids and proteins was identified in marine planktonic fungi. These biochemical signatures, and an elemental composition indicative of a marine planktonic source, have potential applications for the assessment of fungal contribution to marine microbial biomass and organic matter reservoirs, and the cycling of carbon and nutrients.

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CRIPPEN, TAWNI L., CYNTHIA L. SHEFFIELD, KATHLEEN ANDREWS, SCOT E. DOWD, ROY J. BONGAERTS, and DAVID J. NISBET. "Planktonic and Biofilm Community Characterization and Salmonella Resistance of 14-Day-Old Chicken Cecal Microflora–Derived Continuous-Flow Cultures†." Journal of Food Protection 71, no. 10 (October 1, 2008): 1981–87. http://dx.doi.org/10.4315/0362-028x-71.10.1981.

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This study evaluated the composition of gastrointestinal bacterial communities in birds during an age in which their susceptibility to Salmonella is highly diminished. One of the challenges to developing probiotics is to develop an efficacious culture of minimal diversity that includes bacteria that are vital contributors to protection from pathogens, but excludes unnecessary species. This study used in vitro continuous-flow culture techniques to test the ability of mixed bacterial cultures acquired from in vivo sources, to resist colonization by a marker Salmonella enterica serovar Typhimurium, and then characterized the constituents of both biofilm and planktonic communities by biochemical, phenotypic, and molecular methods. These cultures, initiated from 14-day-old chicks, were all able to restrict colonization by Salmonella in an average of 10 days. Eighteen species of bacteria from 10 different genera were characterized. However, each culture contained a mixture of only 11 species, which included lactic acid bacteria. Biofilms contained less than 50% of the species found in the planktonic communities. Although not adults, the diversity of microbes within the cecal cultures from 14-day-old birds represents a community complex enough to oppose colonization by a nonindigenous bacteria in vitro. These results describe bacterial mixtures containing less diversity than in previously described avian protective cultures.

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Tallada, Sheetal, Grant Hall, Daniel Barich, Rachael M. Morgan-Kiss, and Joan L. Slonczewski. "Antibiotic resistance genes and taxa analysis from mat and planktonic microbiomes of Antarctic perennial ice-covered Lake Fryxell and Lake Bonney." Antarctic Science 34, no. 6 (December 2022): 408–22. http://dx.doi.org/10.1017/s0954102022000360.

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AbstractThe perennial ice-covered lakes of the Antarctic McMurdo Dry Valleys harbour oligotrophic microbial communities that are separated geographically from other aquatic systems. Their microbiomes include planktonic microbes as well as lift-off mat communities that emerge from the ice. We used the ShortBRED protein family profiler to quantify the antibiotic resistance genes (ARGs) from metagenomes of lift-off mats emerging from ice and from filtered water samples of Lake Fryxell and Lake Bonney. The overall proportion of ARG hits was similar to that found in temperate-zone rural ponds with moderate human inputs. Specific ARGs showed distinct distributions for the two lakes and for mat vs planktonic sources. Metagenomic taxa distributions showed that mat phototrophs consisted mainly of cyanobacteria or Betaproteobacteria, whereas the water column phototrophs were mainly protists. An enrichment culture of the Betaproteobacterium Rhodoferax antarcticus from a Lake Fryxell mat sample showed an unusual mat-forming phenotype not previously reported for this species. Its genome showed no ARGs associated with Betaproteobacteria but had ARGs consistent with a minor Pseudomonas component. The Antarctic lake mats and water showed specific ARGs distinctive to the mat and water sources, but overall ARG levels were similar to those of temperate water bodies with moderate human inputs.

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Käse, Laura, Alexandra C. Kraberg, Katja Metfies, Stefan Neuhaus, Pim A. A. Sprong, Bernhard M. Fuchs, Maarten Boersma, and Karen H. Wiltshire. "Rapid succession drives spring community dynamics of small protists at Helgoland Roads, North Sea." Journal of Plankton Research 42, no. 3 (May 2020): 305–19. http://dx.doi.org/10.1093/plankt/fbaa017.

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Abstract The dynamics of diatoms and dinoflagellates have been monitored for many decades at the Helgoland Roads Long-Term Ecological Research site and are relatively well understood. In contrast, small-sized eukaryotic microbes and their community changes are still much more elusive, mainly due to their small size and uniform morphology, which makes them difficult to identify microscopically. By using next-generation sequencing, we wanted to shed light on the Helgoland planktonic community dynamics, including nano- and picoplankton, during a spring bloom. We took samples from March to May 2016 and sequenced the V4 region of the 18S rDNA. Our results showed that mixotrophic and heterotrophic taxa were more abundant than autotrophic diatoms. Dinoflagellates dominated the sequence assemblage, and several small-sized eukaryotic microbes like Haptophyta, Choanoflagellata, Marine Stramenopiles and Syndiniales were identified. A diverse background community including taxa from all size classes was present during the whole sampling period. Five phases with several communities were distinguished. The fastest changes in community composition took place in phase 3, while the communities from phases 1 to 5 were more similar to each other despite contrasting environmental conditions. Synergy effects of next-generation sequencing and traditional methods may be exploited in future long-term observations.

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Wainright, SC. "Sediment-to-water fluxes of particulate material and microbes by resuspension and their contribution to the planktonic food web." Marine Ecology Progress Series 62 (1990): 271–81. http://dx.doi.org/10.3354/meps062271.

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Schilirò, T., T. Tommasi, C. Armato, D. Hidalgo, D. Traversi, S. Bocchini, G. Gilli, and C. F. Pirri. "The study of electrochemically active planktonic microbes in microbial fuel cells in relation to different carbon-based anode materials." Energy 106 (July 2016): 277–84. http://dx.doi.org/10.1016/j.energy.2016.03.004.

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Santoferrara, Luciana F., Jean-David Grattepanche, Laura A. Katz, and George B. McManus. "Pyrosequencing for assessing diversity of eukaryotic microbes: analysis of data on marine planktonic ciliates and comparison with traditional methods." Environmental Microbiology 16, no. 9 (February 18, 2014): 2752–63. http://dx.doi.org/10.1111/1462-2920.12380.

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Béjà, Oded, Eugene V. Koonin, L. Aravind, Lance T. Taylor, Heidi Seitz, Jefferey L. Stein, Daniel C. Bensen, Robert A. Feldman, Ronald V. Swanson, and Edward F. DeLong. "Comparative Genomic Analysis of Archaeal Genotypic Variants in a Single Population and in Two Different Oceanic Provinces." Applied and Environmental Microbiology 68, no. 1 (January 2002): 335–45. http://dx.doi.org/10.1128/aem.68.1.335-345.2002.

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ABSTRACT Planktonic crenarchaeotes are present in high abundance in Antarctic winter surface waters, and they also make up a large proportion of total cell numbers throughout deep ocean waters. To better characterize these uncultivated marine crenarchaeotes, we analyzed large genome fragments from individuals recovered from a single Antarctic picoplankton population and compared them to those from a representative obtained from deeper waters of the temperate North Pacific. Sequencing and analysis of the entire DNA insert from one Antarctic marine archaeon (fosmid 74A4) revealed differences in genome structure and content between Antarctic surface water and temperate deepwater archaea. Analysis of the predicted gene products encoded by the 74A4 sequence and those derived from a temperate, deepwater planktonic crenarchaeote (fosmid 4B7) revealed many typical archaeal proteins but also several proteins that so far have not been detected in archaea. The unique fraction of marine archaeal genes included, among others, those for a predicted RNA-binding protein of the bacterial cold shock family and a eukaryote-type Zn finger protein. Comparison of closely related archaea originating from a single population revealed significant genomic divergence that was not evident from 16S rRNA sequence variation. The data suggest that considerable functional diversity may exist within single populations of coexisting microbial strains, even those with identical 16S rRNA sequences. Our results also demonstrate that genomic approaches can provide high-resolution information relevant to microbial population genetics, ecology, and evolution, even for microbes that have not yet been cultivated.

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Manna, Vincenzo, Cinzia Fabbro, Federica Cerino, Matteo Bazzaro, Paola Del Negro, and Mauro Celussi. "Effect of an extreme cold event on the metabolism of planktonic microbes in the northernmost basin of the Mediterranean Sea." Estuarine, Coastal and Shelf Science 225 (September 2019): 106252. http://dx.doi.org/10.1016/j.ecss.2019.106252.

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Xue, Haili, Xiao Lan, Haoguang Liang, and Qin Zhang. "Characteristics and Environmental Factors of Stoichiometric Homeostasis of Soil Microbial Biomass Carbon, Nitrogen and Phosphorus in China." Sustainability 11, no. 10 (May 16, 2019): 2804. http://dx.doi.org/10.3390/su11102804.

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Marine studies have shown that the carbon:nitrogen:phosphorus (C:N:P) atomic ratio in planktonic organisms is generally 106:16:1, which is known as the “Redfield ratio”. This raises the question of whether there are similar patterns in terrestrial organisms, particularly in soil. In this study, we extracted 404 datasets from the literature to analyze the ecological stoichiometry of C, N and P, both in the soil and in the soil microbial biomass in China; additionally, we assessed their relationships with environmental factors, and calculated the homeostasis coefficient (H) of soil microbial biomass. First, although the concentrations of C, N and P in soil and soil microbial biomass showed high spatial heterogeneity, the atomic C:N:P ratios in the soil and soil microbial biomass were relatively consistent at the national scale. Second, the influences of temperature and precipitation on stoichiometric relationships among C, N and P in the soil and soil microbial biomass were limited in China; however, they decreased with the increase in soil pH. Third, the degree of stoichiometric homeostasis for soil microbes spanned a wide range, from non-homeostasis to strict homeostasis. For single elements, most of the soil microbes’ H ranged from 1.01 to 5.00; for elemental ratios, most of the soil microbes’ H displayed strict homeostasis. This study indicates that the “Redfield-like” ratio exists in the soil microbial biomass in the 0–20 cm soil layer in China, with an atomic C:N:P ratio of 66:8:1 and it is close to the atomic C:N:P ratio in the soil (66:5:1) of terrestrial ecosystems. In addition to the N:P ratio in plants, the soil microbial biomass N:P ratio may also be used to judge the nutrient limitations because of its high stability.

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Lee, Jin-Hyung, Yong-Guy Kim, Sunyoung Park, Liangbin Hu, and Jintae Lee. "Phytopigment Alizarin Inhibits Multispecies Biofilm Development by Cutibacterium acnes, Staphylococcus aureus, and Candida albicans." Pharmaceutics 14, no. 5 (May 12, 2022): 1047. http://dx.doi.org/10.3390/pharmaceutics14051047.

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Acne vulgaris is a common chronic inflammatory skin disease involving Cutibacterium acnes with other skin commensals such as Staphylococcus aureus and Candida albicans in the anaerobic and lipid-rich conditions of pilosebaceous units. These microbes readily form multispecies biofilms that are tolerant of traditional antibiotics as well as host immune systems. The phytopigment alizarin was previously found to prevent biofilm formation by S. aureus and C. albicans strains under aerobic conditions. Hence, we hypothesized that alizarin might control C. acnes and multispecies biofilm development. We found that under anaerobic conditions, alizarin efficiently inhibited single biofilm formation and multispecies biofilm development by C. acnes, S. aureus, and C. albicans without inhibiting planktonic cell growth. Alizarin increased the hydrophilicities of S. aureus and C. albicans cells, decreased lipase production by S. aureus, diminished agglutination by C. acnes, and inhibited the aggregation of C. albicans cells. Furthermore, the co-administration of alizarin and antibiotics enhanced the antibiofilm efficacies of alizarin against C. acnes. A transcriptomic study showed that alizarin repressed the transcriptions of various biofilm-related genes such as lipase, hyaluronate lyase, adhesin/invasion-related, and virulence-related genes of C. acnes. Furthermore, alizarin at 100 µg/mL prevented C. acnes biofilm development on porcine skin. Our results show that alizarin inhibits multispecies biofilm development by acne-causing microbes and suggest it might be a useful agent for treating or preventing C. acnes-causing skin diseases.

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Wolcott, Randy. "Biofilm and catheter-related bloodstream infections." British Journal of Nursing 30, no. 8 (April 22, 2021): S4—S9. http://dx.doi.org/10.12968/bjon.2021.30.8.s4.

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Careful attention to detail and adherence to procedure guidelines when inserting and managing intravascular catheters has decreased the incidence of catheter-related bloodstream infections (CRBSIs). In order to limit these, health professionals must understand the underlying microbiology. Biofilms can explain the clinical findings most often seen with CRBSIs, yet they are poorly understood within medicine. Bacteria growing on solid surfaces such as a catheter are predominantly in biofilm phenotype, with a group of genes active that allow the bacteria to be tolerant to antiseptics and antibiotics by producing a self-secreted protective matrix. It is unclear whether it is planktonic seeding or small fragments of biofilm breaking off into the bloodstream that eventually results in the acute infection. The literature identifies four routes for microbes to adhere to a catheter and start biofilm formation: catheter contact, catheter insertion, catheter management and non-catheter-related sources. Routine clinical culture methods are inadequate to fully identify microbes producing catheter biofilm and/or bloodstream infection, therefore DNA methods may be required to diagnose CRBSIs. Treatment is removal and reinsertion of the catheter in a different site when possible. However, antibiofilm strategies can be employed to try to salvage the catheter. The use of high-dose antiseptics or antibiotics for long durations inside the catheter and hub (antibiotic/antiseptic lock) can suppress biofilm enough to reduce the seeding of the blood below a level where the patient's immune system can prevent bloodstream infection.

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Kubiczek, Dennis, Heinz Raber, Melaine Gonzalez-García, Fidel Morales-Vicente, Ludger Staendker, Anselmo J. Otero-Gonzalez, and Frank Rosenau. "Derivates of the Antifungal Peptide Cm-p5 Inhibit Development of Candida auris Biofilms In Vitro." Antibiotics 9, no. 7 (June 27, 2020): 363. http://dx.doi.org/10.3390/antibiotics9070363.

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Growth in biofilms as a fascinating and complex microbial lifestyle has become widely accepted as one of the key features of pathogenic microbes, to successfully express their full virulence potential and environmental persistence. This also increases the threat posed by Candida auris, which has a high intrinsic ability to persist on abiotic surfaces including those of surgical instruments and medical tubing. In a previous study, cyclic and helical-stabilized analogues of the antifungal peptide Cm-p5 were designed and synthetized, and proved to have increased activities against C. albicans and C. parapsilosis, but not against planktonic C. auris cells cultivated in suspension cultures. Here, we demonstrate, initially, that these derivatives, however, exhibited semi-inhibitory concentrations between 10–21 µg/mL toward C. auris biofilms. Maturated biofilms were also arrested between 71–97%. These novel biofilm inhibitors may open urgently needed new routes for the development of novel drugs and treatments for the next stage of fight against C. auris.

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Taylor, Gordon T. "Windows into Microbial Seascapes: Advances in Nanoscale Imaging and Application to Marine Sciences." Annual Review of Marine Science 11, no. 1 (January 3, 2019): 465–90. http://dx.doi.org/10.1146/annurev-marine-121916-063612.

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Geochemical cycles of all nonconservative elements are mediated by microorganisms over nanometer spatial scales. The pelagic seascape is known to possess microstructure imposed by heterogeneous distributions of particles, polymeric gels, biologically important chemicals, and microbes. While indispensable, most traditional oceanographic observational approaches overlook this heterogeneity and ignore subtleties, such as activity hot spots, symbioses, niche partitioning, and intrapopulation phenotypic variations, that can provide a deeper mechanistic understanding of planktonic ecosystem function. As part of the movement toward cultivation-independent tools in microbial oceanography, techniques to examine the ecophysiology of individual populations and their role in chemical transformations at spatial scales relevant to microorganisms have been developed. This review presents technologies that enable geochemical and microbiological interrogations at spatial scales ranging from 0.02 to a few hundred micrometers, particularly focusing on atomic force microscopy, nanoscale secondary ion mass spectrometry, and confocal Raman microspectroscopy and introducing promising approaches for future applications in marine sciences.

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Wang, Kai-Ling, Zheng-Rong Dou, Gao-Fen Gong, Hai-Feng Li, Bei Jiang, and Ying Xu. "Anti-Larval and Anti-Algal Natural Products from Marine Microorganisms as Sources of Anti-Biofilm Agents." Marine Drugs 20, no. 2 (January 21, 2022): 90. http://dx.doi.org/10.3390/md20020090.

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Bacteria growing inside biofilms are more resistant to hostile environments, conventional antibiotics, and mechanical stresses than their planktonic counterparts. It is estimated that more than 80% of microbial infections in human patients are biofilm-based, and biofouling induced by the biofilms of some bacteria causes serious ecological and economic problems throughout the world. Therefore, exploring highly effective anti-biofilm compounds has become an urgent demand for the medical and marine industries. Marine microorganisms, a well-documented and prolific source of natural products, provide an array of structurally distinct secondary metabolites with diverse biological activities. However, up to date, only a handful of anti-biofilm natural products derived from marine microorganisms have been reported. Meanwhile, it is worth noting that some promising antifouling (AF) compounds from marine microbes, particularly those that inhibit settlement of fouling invertebrate larvae and algal spores, can be considered as potential anti-biofilm agents owing to the well-known knowledge of the correlations between biofilm formation and the biofouling process of fouling organisms. In this review, a total of 112 anti-biofilm, anti-larval, and anti-algal natural products from marine microbes and 26 of their synthetic analogues are highlighted from 2000 to 2021. These compounds are introduced based on their microbial origins, and then categorized into the following different structural groups: fatty acids, butenolides, terpenoids, steroids, phenols, phenyl ethers, polyketides, alkaloids, flavonoids, amines, nucleosides, and peptides. The preliminary structure-activity relationships (SAR) of some important compounds are also briefly discussed. Finally, current challenges and future research perspectives are proposed based on opinions from many previous reviews.

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Kanso, Eva A., Rubens M. Lopes, J. Rudi Strickler, John O. Dabiri, and John H. Costello. "Teamwork in the viscous oceanic microscale." Proceedings of the National Academy of Sciences 118, no. 29 (July 16, 2021): e2018193118. http://dx.doi.org/10.1073/pnas.2018193118.

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Nutrient acquisition is crucial for oceanic microbes, and competitive solutions to solve this challenge have evolved among a range of unicellular protists. However, solitary solutions are not the only approach found in natural populations. A diverse array of oceanic protists form temporary or even long-lasting attachments to other protists and marine aggregates. Do these planktonic consortia provide benefits to their members? Here, we use empirical and modeling approaches to evaluate whether the relationship between a large centric diatom, Coscinodiscus wailesii, and a ciliate epibiont, Pseudovorticella coscinodisci, provides nutrient flux benefits to the host diatom. We find that fluid flows generated by ciliary beating can increase nutrient flux to a diatom cell surface four to 10 times that of a still cell without ciliate epibionts. This cosmopolitan species of diatom does not form consortia in all environments but frequently joins such consortia in nutrient-depleted waters. Our results demonstrate that symbiotic consortia provide a cooperative alternative of comparable or greater magnitude to sinking for enhancement of nutrient acquisition in challenging environments.

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Płaza, Grażyna, and Varenyam Achal. "Biosurfactants: Eco-Friendly and Innovative Biocides against Biocorrosion." International Journal of Molecular Sciences 21, no. 6 (March 20, 2020): 2152. http://dx.doi.org/10.3390/ijms21062152.

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Corrosion influenced by microbes, commonly known as microbiologically induced corrosion (MIC), is associated with biofilm, which has been one of the problems in the industry. The damages of industrial equipment or infrastructures due to corrosion lead to large economic and environmental problems. Synthetic chemical biocides are now commonly used to prevent corrosion, but most of them are not effective against the biofilms, and they are toxic and not degradable. Biocides easily kill corrosive bacteria, which are as the planktonic and sessile population, but they are not effective against biofilm. New antimicrobial and eco-friendly substances are now being developed. Biosurfactants are proved to be one of the best eco-friendly anticorrosion substances to inhibit the biocorrosion process and protect materials against corrosion. Biosurfactants have recently became one of the important products of bioeconomy with multiplying applications, while there is scare knowledge on their using in biocorrosion treatment. In this review, the recent findings on the application of biosurfactants as eco-friendly and innovative biocides against biocorrosion are highlighted.

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Szlauer, Wojciech, Ewa Obłąk, Emil Paluch, and Katarzyna Baldy-Chudzik. "Biofilm and methods of its eradication." Postępy Higieny i Medycyny Doświadczalnej 73 (August 26, 2019): 397–413. http://dx.doi.org/10.5604/01.3001.0013.1605.

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Microorganisms occur in the natural environment in the form of planktonic or create biofilms, i.e. communities of cells surrounded by the extracellular matrix. This is possible due to the phenomenon of quorum sensing, i.e. the ability of microorganisms to estimate their own density and change the expression of genes in response to them. Within such a structure, microorganisms are protected against harmful environmental conditions, their metabolic profile and the level of expression of individual genes are also changed, which leads to an increase in the pathogenicity of organisms associated in the form of biofilms. They pose a huge threat to hospital patients because they are capable of residing abiotic surfaces, such as catheters and endoprostheses, and can cause infection. The current methods of combating microbes with antibiotics and fungicides lose their effectiveness, both due to the increasing drug resistance of clinically relevant strains, but also to the very properties of biofilms. This determines the need to search for new and effective methods (physical, chemical and biological) to eradicate biofilms

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Caruso, Gabriella, Maurizio Azzaro, Carmela Caroppo, Franco Decembrini, Luis Salvador Monticelli, Marcella Leonardi, Giovanna Maimone, Renata Zaccone, and Rosabruna La Ferla. "Microbial community and its potential as descriptor of environmental status." ICES Journal of Marine Science 73, no. 9 (June 19, 2016): 2174–77. http://dx.doi.org/10.1093/icesjms/fsw101.

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Abstract Planktonic communities hold a relevant role within the EU Marine Strategy Framework Directive (MSFD). In view of reaching the Good Environmental Status of marine ecosystems, within this Directive the phyto- and zooplanktonic communities have received great attention, while Prokaryotes (Bacteria, Archaea, and Cyanobacteria) have been neglected. Indeed, the relevance of microbes (particularly of the faecal pollution indicators) as water quality indicators, the role that microorganisms play within the biogeochemical fluxes and in the whole ecosystem functioning, are all important features that deserve to be focused within the MSFD. The present study aims at reviewing the main issues where prokaryotic variables find useful application as descriptors of environmental status, trying to develop a panel of prokaryotic indicators suitable for the environmental quality assessment. From a survey of scientific literature and on field datasets, prokaryotic abundance and activities (enzymatic hydrolysis, prokaryotic production, and respiratory rates) are here chosen as early warning sentinels to detect changes in environmental quality, using an integrated approach with trophic (chlorophyll-a, particulate and dissolved organic matter) measurements.

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Skłodowski, Karol, Sylwia Joanna Chmielewska-Deptuła, Ewelina Piktel, Przemysław Wolak, Tomasz Wollny, and Robert Bucki. "Metallic Nanosystems in the Development of Antimicrobial Strategies with High Antimicrobial Activity and High Biocompatibility." International Journal of Molecular Sciences 24, no. 3 (January 20, 2023): 2104. http://dx.doi.org/10.3390/ijms24032104.

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Antimicrobial resistance is a major and growing global problem and new approaches to combat infections caused by antibiotic resistant bacterial strains are needed. In recent years, increasing attention has been paid to nanomedicine, which has great potential in the development of controlled systems for delivering drugs to specific sites and targeting specific cells, such as pathogenic microbes. There is continued interest in metallic nanoparticles and nanosystems based on metallic nanoparticles containing antimicrobial agents attached to their surface (core shell nanosystems), which offer unique properties, such as the ability to overcome microbial resistance, enhancing antimicrobial activity against both planktonic and biofilm embedded microorganisms, reducing cell toxicity and the possibility of reducing the dosage of antimicrobials. The current review presents the synergistic interactions within metallic nanoparticles by functionalizing their surface with appropriate agents, defining the core structure of metallic nanoparticles and their use in combination therapy to fight infections. Various approaches to modulate the biocompatibility of metallic nanoparticles to control their toxicity in future medical applications are also discussed, as well as their ability to induce resistance and their effects on the host microbiome.

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Emerson, Ray J., and Terri A. Camesano. "Nanoscale Investigation of Pathogenic Microbial Adhesion to a Biomaterial." Applied and Environmental Microbiology 70, no. 10 (October 2004): 6012–22. http://dx.doi.org/10.1128/aem.70.10.6012-6022.2004.

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ABSTRACT Microbial infections of medical implants occur in more than 2 million surgical cases each year in the United States alone. These increase patient morbidity and mortality, as well as patient cost and recovery time. Many treatments are available, but none are guaranteed to remove the infection. In many cases, the device infections are caused by the adhesion of microbes to the implant, ensuing growth, pathogenesis, and dissemination. The purpose of this work is to examine the initial events in microbial adhesion by simulating the approach and contact between a planktonic cell, immobilized on an atomic force microscope (AFM) cantilever, and a biomaterial or biofilm substrate. The two model microbes used in this study, Candida parapsilosis (ATCC 90018) and Pseudomonas aeruginosa (ATCC 10145), were chosen for both their clinical relevance and their ease of acquisition and handling in the laboratory setting. Attractive interactions exist between C. parapsilosis and both unmodified silicone rubber and P. aeruginosa biofilms. Using C. parapsilosis cells immobilized on AFM cantilevers with a silicone substrate, we have measured attractive forces of 4.3 ± 0.25 nN in the approach portion of the force cycle. On P. aeruginosa biofilms, the magnitude of the attractive force decreases to 2.0 ± 0.40 nN and is preceded by a 2.0-nN repulsion at approximately 75 nm from the cell surface. These data suggest that C. parapsilosis may adhere to both silicone rubber and P. aeruginosa biofilms, possibly contributing to patient morbidity and mortality. Characterization of cell-biomaterial and cell-cell interactions allows for a quantitative link between the physicomechanical and physicochemical properties of implant materials and the nanoscale interactions leading to microbial colonization and infection.

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Szczolko, Wojciech, Magdalena Ratajczak, Tomasz Koczorowski, Dorota Kaminska, Tomasz Goslinski, and Jolanta Dlugaszewska. "Promising Photocytotoxicity of Water-Soluble Phtalocyanine against Planktonic and Biofilm Pseudomonas aeruginosa Isolates from Lower Respiratory Tract and Chronic Wounds." Applied Sciences 12, no. 8 (April 7, 2022): 3707. http://dx.doi.org/10.3390/app12083707.

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Alternative methods of killing microbes have been extensively researched in connection with the widespread appearance of antibiotic resistance among pathogenic bacteria. In this study, we report on in vitro antimicrobial phototoxicity research of cationic phthalocyanine with 2-(4-N-methylmorpholin-4-ium-4-yl)ethoxy substituents against selected clinical strains of Pseudomonas aeruginosa isolated from the lower respiratory tract and chronic wounds. The microorganisms tested in the research were analyzed in terms of drug resistance and biofilm formation. The photocytotoxic effect of phthalocyanine was determined by the reduction factor of bacteria. The studied cationic phthalocyanine at a concentration of 1.0 × 10−4 M, when activated by light, revealed a significant reduction factor, ranging from nearly 4 to 6 log, of P. aeruginosa cells when compared to the untreated control group. After single irradiation, a decrease in the number of bacteria in biofilm ranging from 1.3 to 4.2 log was observed, whereas the second treatment significantly improved the bacterial reduction factor from 3.4 to 5.5 log. It is worth mentioning that a boosted cell-death response was observed after the third irradiation, with a bacterial reduction factor ranging from 4.6 to 6.4 log. According to the obtained results, the tested photosensitizer can be considered as a potential antimicrobial photodynamic therapy against multidrug-resistant P. aeruginosa.

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Woźniak, Agata, Beata Kruszewska, Michał Karol Pierański, Michał Rychłowski, and Mariusz Grinholc. "Antimicrobial Photodynamic Inactivation Affects the Antibiotic Susceptibility of Enterococcus spp. Clinical Isolates in Biofilm and Planktonic Cultures." Biomolecules 11, no. 5 (May 5, 2021): 693. http://dx.doi.org/10.3390/biom11050693.

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Enterococcus faecium and Enterococcus faecalis are opportunistic pathogens that can cause a vast variety of nosocomial infections. Moreover, E. faecium belongs to the group of ESKAPE microbes, which are the main cause of hospital-acquired infections and are especially difficult to treat because of their resistance to many antibiotics. Antimicrobial photodynamic inactivation (aPDI) represents an alternative to overcome multidrug resistance problems. This process requires the simultaneous presence of oxygen, visible light, and photosensitizing compounds. In this work, aPDI was used to resensitize Enterococcus spp. isolates to antibiotics. Antibiotic susceptibility testing according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations was combined with synergy testing methods recommended by the American Society for Microbiology. Two clinical isolates, E. faecalis and E. faecium, were treated with a combination of aPDI utilizing rose bengal (RB) or fullerene (FL) derivative as photosensitizers, antimicrobial blue light (aBL), and 10 recommended antibiotics. aPDI appeared to significantly impact the survival rate of both isolates, while aBL had no significant effect. The synergy testing results differed between strains and utilized methods. Synergy was observed for RB aPDI in combination with gentamycin, ciprofloxacin and daptomycin against E. faecalis. For E. faecium, synergy was observed between RB aPDI and gentamycin or ciprofloxacin, while for RB aPDI with vancomycin or daptomycin, antagonism was observed. A combination of FL aPDI gives a synergistic effect against E. faecalis only with imipenem. Postantibiotic effect tests for E. faecium demonstrated that this isolate exposed to aPDI in combination with gentamycin, streptomycin, tigecycline, doxycycline, or daptomycin exhibits delayed growth in comparison to untreated bacteria. The results of synergy testing confirmed the effectiveness of aPDI in resensitization of the bacteria to antibiotics, which presents great potential in the treatment of infections caused by multidrug-resistant strains.

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Girard, Catherine, Valérie Langlois, Adrien Vigneron, Warwick F. Vincent, and Alexander I. Culley. "Seasonal Regime Shift in the Viral Communities of a Permafrost Thaw Lake." Viruses 12, no. 11 (October 22, 2020): 1204. http://dx.doi.org/10.3390/v12111204.

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Permafrost thaw lakes including thermokarst lakes and ponds are ubiquitous features of Subarctic and Arctic landscapes and are hotspots of microbial activity. Input of terrestrial organic matter into the planktonic microbial loop of these lakes may greatly amplify global greenhouse gas emissions. This microbial loop, dominated in the summer by aerobic microorganisms including phototrophs, is radically different in the winter, when metabolic processes shift to the anaerobic degradation of organic matter. Little is known about the viruses that infect these microbes, despite evidence that viruses can control microbial populations and influence biogeochemical cycling in other systems. Here, we present the results of a metagenomics-based study of viruses in the larger than 0.22 µm fraction across two seasons (summer and winter) in a permafrost thaw lake in Subarctic Canada. We uncovered 351 viral populations (vOTUs) in the surface waters of this lake, with diversity significantly greater during the summer. We also identified and characterized several phage genomes and prophages, which were mostly present in the summer. Finally, we compared the viral community of this waterbody to other habitats and found unexpected similarities with distant bog lakes in North America.

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Jung, Yong-Gyun, Jungil Choi, Soo-Kyoung Kim, Joon-Hee Lee, and Sunghoon Kwon. "Embedded Biofilm, a New Biofilm Model Based on the Embedded Growth of Bacteria." Applied and Environmental Microbiology 81, no. 1 (October 17, 2014): 211–19. http://dx.doi.org/10.1128/aem.02311-14.

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ABSTRACTA variety of systems have been developed to study biofilm formation. However, most systems are based on the surface-attached growth of microbes under shear stress. In this study, we designed a microfluidic channel device, called a microfluidic agarose channel (MAC), and found that microbial cells in the MAC system formed an embedded cell aggregative structure (ECAS). ECASs were generated from the embedded growth of bacterial cells in an agarose matrix and better mimicked the clinical environment of biofilms formed within mucus or host tissue under shear-free conditions. ECASs were developed with the production of extracellular polymeric substances (EPS), the most important feature of biofilms, and eventually burst to release planktonic cells, which resembles the full developmental cycle of biofilms. Chemical and genetic effects have also confirmed that ECASs are a type of biofilm. Unlike the conventional biofilms formed in the flow cell model system, this embedded-type biofilm completes the developmental cycle in only 9 to 12 h and can easily be observed with ordinary microscopes. We suggest that ECASs are a type of biofilm and that the MAC is a system for observing biofilm formation.

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Rodesney, Christopher A., Brian Roman, Numa Dhamani, Benjamin J. Cooley, Parag Katira, Ahmed Touhami, and Vernita D. Gordon. "Mechanosensing of shear by Pseudomonas aeruginosa leads to increased levels of the cyclic-di-GMP signal initiating biofilm development." Proceedings of the National Academy of Sciences 114, no. 23 (May 22, 2017): 5906–11. http://dx.doi.org/10.1073/pnas.1703255114.

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Biofilms are communities of sessile microbes that are phenotypically distinct from their genetically identical, free-swimming counterparts. Biofilms initiate when bacteria attach to a solid surface. Attachment triggers intracellular signaling to change gene expression from the planktonic to the biofilm phenotype. For Pseudomonas aeruginosa, it has long been known that intracellular levels of the signal cyclic-di-GMP increase upon surface adhesion and that this is required to begin biofilm development. However, what cue is sensed to notify bacteria that they are attached to the surface has not been known. Here, we show that mechanical shear acts as a cue for surface adhesion and activates cyclic-di-GMP signaling. The magnitude of the shear force, and thereby the corresponding activation of cyclic-di-GMP signaling, can be adjusted both by varying the strength of the adhesion that binds bacteria to the surface and by varying the rate of fluid flow over surface-bound bacteria. We show that the envelope protein PilY1 and functional type IV pili are required mechanosensory elements. An analytic model that accounts for the feedback between mechanosensors, cyclic-di-GMP signaling, and production of adhesive polysaccharides describes our data well.

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Journal articles on the topic 'Planktonic microbes'

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