Literatura científica selecionada sobre o tema "Biopolymers from marine and bacterial origins"

ABSTRACT Our understanding of the degradation of organic matter will benefit from a greater appreciation for the genes encoding enzymes involved in the hydrolysis of biopolymers such as chitin, one of the most abundant polymers in nature. To isolate representative and abundant chitinase genes from uncultivated marine bacteria, we constructed libraries of genomic DNA isolated from coastal and estuarine waters. The libraries were screened for genes encoding proteins that hydrolyze a fluorogenic analogue of chitin, 4-methylumbelliferyl β-d-N,N′-diacetylchitobioside (MUF-diNAG). The abundance of clones capable of MUF-diNAG hydrolysis was higher in the library constructed with DNA from the estuary than in that constructed with DNA from coastal waters, although the abundance of positive clones was also dependent on the method used to screen the library. Plaque assays revealed nine MUF-diNAG-positive clones of 75,000 screened for the estuarine sample and two clones of 750,000 for the coastal sample. A microtiter plate assay revealed approximately 1 positive clone for every 500 clones screened in the coastal library. The number of clones detected with the plaque assay was consistent with estimates of the portion of culturable bacteria that degrade chitin. Our results suggest that culture-dependent methods do not greatly underestimate the portion of marine bacterial communities capable of chitin degradation.

Research in tissue engineering and regenerative medicine has an ever-increasing need for innovative biomaterials suitable for the production of wound-dressing devices and artificial skin-like substitutes. Marine collagen is one of the most promising biomaterials for the production of such devices. In this study, for the first time, 2D collagen membranes (2D-CMs) created from the extracellular matrix extract of the marine demosponge Chondrosia reniformis have been evaluated in vitro as possible tools for wound healing. Fibrillar collagen was extracted from a pool of fresh animals and used for the creation of 2D-CMs, in which permeability to water, proteins, and bacteria, and cellular response in the L929 fibroblast cell line were evaluated. The biodegradability of the 2D-CMs was also assessed by following their degradation in PBS and collagenase solutions for up to 21 days. Results showed that C. reniformis-derived membranes avoided liquid and protein loss in the regeneration region and also functioned as a strong barrier against bacteria infiltration into a wound. Gene expression analyses on fibroblasts stated that their interaction with 2D-CMs is able to improve fibronectin production without interfering with the regular extracellular matrix remodeling processes. These findings, combined with the high extraction yield of fibrillar collagen obtained from C. reniformis with a solvent-free approach, underline how important further studies on the aquaculture of this sponge could be for the sustainable production and biotechnological exploitation of this potentially promising and peculiar biopolymer of marine origin.

ABSTRACT Naturally occurring plasmids isolated from heterotrophic bacterial isolates originating from coastal California marine sediments were characterized by analyzing their incompatibility and replication properties. Previously, we reported on the lack of DNA homology between plasmids from the culturable bacterial population of marine sediments and the replicon probes specific for a number of well-characterized incompatibility and replication groups (P. A. Sobecky, T. J. Mincer, M. C. Chang, and D. R. Helinski, Appl. Environ. Microbiol. 63:888–895, 1997). In the present study we isolated 1.8- to 2.3-kb fragments that contain functional replication origins from one relatively large (30-kb) and three small (<10-kb) naturally occurring plasmids present in different marine isolates. 16S rRNA sequence analyses indicated that the four plasmid-bearing marine isolates belonged to the α and γ subclasses of the classProteobacteria. Three of the marine sediment isolates are related to the γ-3 subclass organisms Vibrio splendidusand Vibrio fischeri, while the fourth isolate may be related to Roseobacter litoralis. Sequence analysis of the plasmid replication regions revealed the presence of features common to replication origins of well-characterized plasmids from clinical bacterial isolates, suggesting that there may be similar mechanisms for plasmid replication initiation in the indigenous plasmids of gram-negative marine sediment bacteria. In addition to replication inEscherichia coli DH5α and C2110, the host ranges of the plasmid replicons, designated repSD41, repSD121, repSD164, and repSD172, extended to marine species belonging to the generaAchromobacter, Pseudomonas,Serratia, and Vibrio. While sequence analysis of repSD41 and repSD121 revealed considerable stretches of homology between the two fragments, these regions do not display incompatibility properties against each other. The replication origin repSD41 was detected in 5% of the culturable plasmid-bearing marine sediment bacterial isolates, whereas the replication origins repSD164 and repSD172 were not detected in any plasmid-bearing bacteria other than the parental isolates. Microbial community DNA extracted from samples collected in November 1995 and June 1997 and amplified by PCR yielded positive signals when they were hybridized with probes specific for repSD41 and repSD172 replication sequences. In contrast, replication sequences specific for repSD164 were not detected in the DNA extracted from marine sediment microbial communities.

Patagonian fjords and channels in southern Chile are heterogeneous ecosystems characterized by the interaction of estuarine and marine waters influencing physical-chemical conditions and biological assemblages. Besides salinity, microbial communities from estuarine and marine origin are naturally subjected to changing organic matter quality and variable nutrient concentrations. In this study, we tackle the response of the bacterial community from estuarine and marine origins associated with two size classes (<0.7 µm and <1.6 µm) to the addition of sterile phytoplankton-derived exudates (PDE) compared to control conditions (no addition). Picoplanktonic cell abundance, active bacterial composition analyzed through 16S rRNA sequencing, changes in dissolved organic carbon (DOC) and δ13C were determined over 5 and 15 days after PDE addition. Our results showed that the active marine bacteria were richer and more diverse than their estuarine counterparts, and were dominated by Alphaproteobacteria and Gammaproteobacteria, respectively. PDE addition in both the fractions and the sample origin resulted in an enrichment throughout the incubation of Rhodobacteracea and Cryimorphaceae families, whereas Epsilonproteobacteria (Arcobacteraceae) were mainly favored in the estuarine experiments. Picoplankton abundance increased with time, but higher cell numbers were found in PDE treatments in both size classes (>2 × 105 cell mL−1). In all the experiments, DOC concentration decreased after eight days of incubation, but shifts in δ13C organic matter composition were greater in the estuarine experiments. Overall, our results indicate that despite their different origins (estuarine versus marine), microbial communities inhabiting the fjord responded to PDE with a faster effect on marine active bacteria.

The synthesis of bioplastic from marine microbes has a great attendance in the realm of biotechnological applications for sustainable eco-management. This study aims to isolate novel strains of poly-β-hydroxybutyrate (PHB)-producing bacteria from the mangrove rhizosphere, Red Sea, Saudi Arabia, and to characterize the extracted polymer. The efficient marine bacterial isolates were identified by the phylogenetic analysis of the 16S rRNA genes as Tamlana crocina, Bacillus aquimaris, Erythrobacter aquimaris, and Halomonas halophila. The optimization of PHB accumulation by E. aquimaris was achieved at 120 h, pH 8.0, 35 °C, and 2% NaCl, using glucose and peptone as the best carbon and nitrogen sources at a C:N ratio of 9.2:1. The characterization of the extracted biopolymer by Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and Gas chromatography-mass spectrometry (GC-MS) proves the presence of hydroxyl, methyl, methylene, methine, and ester carbonyl groups, as well as derivative products of butanoic acid, that confirmed the structure of the polymer as PHB. This is the first report on E. aquimaris as a PHB producer, which promoted the hypothesis that marine rhizospheric bacteria were a new area of research for the production of biopolymers of commercial value.

Marine tunicates are identified as a potential source of marine natural products (MNPs), demonstrating a wide range of biological properties, like antimicrobial and anticancer activities. The symbiotic relationship between tunicates and specific microbial groups has revealed the acquisition of microbial compounds by tunicates for defensive purpose. For instance, yellow pigmented compounds, “tambjamines”, produced by the tunicate, Sigillina signifera (Sluiter, 1909), primarily originated from their bacterial symbionts, which are involved in their chemical defense function, indicating the ecological role of symbiotic microbial association with tunicates. This review has garnered comprehensive literature on MNPs produced by tunicates and their symbiotic microbionts. Various sections covered in this review include tunicates’ ecological functions, biological activities, such as antimicrobial, antitumor, and anticancer activities, metabolic origins, utilization of invasive tunicates, and research gaps. Apart from the literature content, 20 different chemical databases were explored to identify tunicates-derived MNPs. In addition, the management and exploitation of tunicate resources in the global oceans are detailed for their ecological and biotechnological implications.

Lignocellulosic materials are composed of cellulose, hemicellulose and lignin and are one of the most abundant biopolymers in marine environments. The extent of the involvement of marine microorganisms in lignin degradation and their contribution to the oceanic carbon cycle remains elusive. In this study, a novel lignin-degrading bacterial strain, LCG003, was isolated from intertidal seawater in Lu Chao Harbor, East China Sea. Phylogenetically, strain LCG003 was affiliated with the genus Aliiglaciecola within the family Alteromonadaceae. Metabolically, strain LCG003 contains various extracellular (signal-fused) glycoside hydrolase genes and carbohydrate transporter genes and can grow with various carbohydrates as the sole carbon source, including glucose, fructose, sucrose, rhamnose, maltose, stachyose and cellulose. Moreover, strain LCG003 contains many genes of amino acid and oligopeptide transporters and extracellular peptidases and can grow with peptone as the sole carbon and nitrogen source, indicating a proteolytic lifestyle. Notably, strain LCG003 contains a gene of dyp-type peroxidase and strain-specific genes involved in the degradation of 4-hydroxy-benzoate and vanillate. We further confirmed that it can decolorize aniline blue and grow with lignin as the sole carbon source. Our results indicate that the Aliiglaciecola species can depolymerize and mineralize lignocellulosic materials and potentially play an important role in the marine carbon cycle.

Biofilms, responsible for many serious drawbacks in the medical and marine environment, can grow on abiotic and biotic surfaces. Commercial anti-biofilm solutions, based on the use of biocides, are available but their use increases the risk of antibiotic resistance and environmental pollution in marine industries. There is an urgent need to work on the development of ecofriendly solutions, formulated without biocidal agents, that rely on the anti-adhesive physico-chemical properties of their materials. In this context, exopolysaccharides (EPSs) are natural biopolymers with complex properties than may be used as anti-adhesive agents. This study is focused on the effect of the EPS MO245, a hyaluronic acid-like polysaccharide, on the growth, adhesion, biofilm maturation, and dispersion of two pathogenic model strains, Pseudomonas aeruginosa sp. PaO1 and Vibrio harveyi DSM19623. Our results demonstrated that MO245 may limit biofilm formation, with a biofilm inhibition between 20 and 50%, without any biocidal activity. Since EPSs have no significant impact on the bacterial motility and quorum sensing factors, our results indicate that physico-chemical interactions between the bacteria and the surfaces are modified due to the presence of an adsorbed EPS layer acting as a non-adsorbing layer.

This study aimed to evaluate the environmental quality of surface water of the Maricá Lagoon System through physicochemical, biochemical and microbiological parameters, in order to assess its environmental quality. Marine influence over the system was evidenced by the salinity and temperature gradients, where the most distant point, in Maricá Lagoon, presented the largest protein, lipid and biopolymeric carbon concentrations. Biopolymers, with predominance of lipids, presented a pattern that differs from the literature for coastal sediments. The concentration of thermotolerant coliforms characterised Maricá Lagoon and Boqueirão Channel as unfit for bathing (60.0 and 66.3 cells.mL-1, respectively). The bacterioplankton in the system proved to be predominantly heterotrophic, a consumer of organic matter, with fermentative, denitrifying and sulfate-reducing metabolism. No esterase enzyme activity was detected, despite the presence of active metabolism, measured by the electron transport system (average of 0.025 µgO2.h-1.mL-1). The bacterial biomass (autotrophic, heterotrophic and coliforms), bacterial respiratory activity and biopolymer parameters evinced a spatial degradation pattern in the Maricá Lagoon System, where the points with less water renewal are the most impacted.

The search for new antibiotics against drug-resistant microbes has been expanded to marine bacteria. Marine bacteria have been proven to be a prolific source of a myriad of novel compounds with potential biological activities. Therefore, this review highlights novel and bioactive compounds from marine bacteria reported during the period of January 2016 to December 2021. Published articles containing novel marine bacterial secondary metabolites that are active against drug-resistant pathogens were collected. Previously described compounds (prior to January 2016) are not included in this review. Unreported compounds during this period that exhibited activity against pathogenic microbes were discussed and compared in order to find the cue of the structure–bioactivity relationship. The results showed that Streptomyces are the most studied bacteria with undescribed bioactive compounds, followed by other genera in the Actinobacteria. We have categorized the structures of the compounds in the present review into four groups, based on their biosynthetic origins, as polyketide derivatives, amino acid derivatives, terpenoids, as well as compounds with mixed origin. These compounds were active against one or more drug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), vancomycin-resistant Enterococci (VRE), multidrug-resistant Mycobacterium tuberculosis (MDR-TB), and amphotericin B-resistant Candida albicans. In addition, some of the compounds also showed activity against biofilm formation of the test bacteria. Some previously undescribed compounds, isolated from marine-derived bacteria during this period, could have a good potential as lead compounds for the development of drug candidates to overcome multidrug-resistant pathogens.

Pour faire face aux impacts de la chimie conventionnelle et des produits pétrosourcés sur la santé humaine et les écosystèmes, la chimie verte et les macromolécules d'origine biologique sont une source infinie d'innovation. Ce projet s'inscrit dans une approche de bioinspiration et repose sur l'utilisation d'enzymes bactériennes dans l'objectif d'évaluer leur potentiel pour : (1) la glucosylation de molécules marines pour la création de filtres solaires, et (2) l'assemblage de polysaccharides marins et bactériens réticulés par des protéines « sur mesure ». Dans le premier cas, il s'agit de produire des molécules inspirées des propriétés anti-UV retrouvées chez certains composés du mucus et des yeux des poissons. Dans le second, d'une stratégie inspirée des associations entre polysaccharides et protéines que l'on trouve dans les peptidoglycanes bactériens ou les carapaces des crustacés. Pour le premier projet, les molécules cibles sont les mycosporines, des métabolites secondaires présents dans une grande variété d'organismes et reconnues pour leur forte capacité d'absorption des rayons UV et leur pouvoir antioxydant. En prenant la mycosporine-sérinol (MSer(OH)) comme modèle, une vingtaine d'α-transglucosylases de la famille GH70 qui utilisent le saccharose comme substrat donneur d'unités glucosyle ont été testées. Une d'entre elle s'est particulièrement démarquée, glucosylant la mycosporine avec un taux de conversion de 95%. Les caractérisations en RMN et spectrométrie de masse ont montré l'ajout de 1 à 3 unités glucosyle, l'espèce prédominante ayant 2 unités sucre sur le même carbone. Dans un deuxième temps, une cascade enzymatique a été développée afin d'allonger la chaîne glucidique préalablement obtenue, toujours à partir de saccharose et de ces mêmes enzymes. Une large gamme de MSer(OH) glucosylées a ainsi été générée, variant par la nature des liaisons osidiques et/ou la taille de la chaine (10 < DP < ~750 000). La photostabilité et les capacités antioxydantes des produits obtenus sont équivalentes à celles de la MSer(OH) libre ou d'antioxydants reconnus, et peuvent donc rivaliser avec des filtres solaires commerciaux. Notamment, une MSer(OH) greffée sur une chaîne de dextrane de plus de 108 g/mol présente des propriétés texturantes intéressantes, la rendant d'autant plus prometteuse pour des formulations médicales ou cosmétiques. Dans le deuxième projet, le choix s'est porté sur le dextrane, la chitine, le chitosane et l'agarose car ce sont des polysaccharides largement disponibles et déjà reconnus dans le domaine des biomatériaux, notamment pour des applications médicales. L'assemblage physique de ces biopolymères est basé sur la création de protéines réticulantes sur-mesure nommées "bridges", correspondant à l'association de 2 modules de liaison aux glucides (CBM) - issus d'enzymes dégradant ou synthétisant ces polymères - liés entre eux par une séquence peptidique plus ou moins flexible. Deux bibliothèques de quatre bridges ont été conçues, produites de manière recombinante chez E. coli, purifiées, et leur affinité pour leurs biopolymères respectifs confirmée. Ensuite, des premiers hydrogels physiques ont été développés en assemblant les polysaccharides avec les « bridges », menant à des différences de texture et de viscosité. Des analyses de rhéologie et de microscopie ont confirmé que ces biomatériaux sont dynamiques et rhéofluidifiants, donc très intéressants comme hydrogels injectables pour l'administration de médicament. Dans l'ensemble, ces premières preuves de concept sont prometteuses et montrent le potentiel de ces matériaux bioinspirés pour différentes applications. Les plus intéressantes sont celles envisagées dans le domaine de la santé, car elles permettraient la formulation de produit respectueux à la fois de la santé humaine et des écosystèmes
To face the adverse impacts of conventional chemistry and fossil-based products on human health and ecosystems, sustainable chemistry (biosynthesis) and bio-based (macro)molecules appear as endless sources of inspiration and innovation. Driven by bioinspired approaches, this project consisted of taking advantage of bacterial enzymes synthesizing polysaccharides of glucosyl units from sucrose to attempt two objectives: (1) the glucosylation of marine molecules for the development of novel UV filter products; and (2) the assembly of marine and bacterial polysaccharides physically cross-linked by tailor-made proteins. The first strategy is inspired by UV-absorbing molecules found in fish mucus and eyes while the second one is inspired by associations found in nature like bacterial peptidoglycans or crustacean crab exoskeleton. In the field of new UV filter products, the target molecules were mycosporines, secondary metabolites found in a wide variety of organisms. They are recognized for their high UV-absorbing properties and antioxidant activity. The aim was to mimic the natural glycosylation of mycosporines by assessing the feasibility of glucosylating these compounds with -transglucosylases from GH70 family and modulating the size of the carbohydrate moiety. Using the mycosporine-serinol (MSer(OH)) as starting molecule, one enzyme stood out from the twenty screened candidates with a remarkable conversion rate of 95%. The glucosylated products were characterized by NMR and mass spectroscopy, showing the addition of 1 to 3 glucosyl units, with the predominant product having two glucosyl units on the same carbon. In a second step, with the objective to extend the glucidic backbone, an enzymatic cascade was developed, again relying on the use of GH70 enzymes and sucrose as glucosyl donor. A wide range of glucosylated-MSer(OH) compounds were synthesized, varying both in linkage specificity and chain length (10 < DP < ~750,000). Interestingly, their photostability and antioxidant capacity are equivalent to those of free MSer(OH) or well-known antioxidants, and therefore, could compete commercial sunscreens. Notably, a MSer(OH) grafted to a dextran chain of more than 108 g/mol exhibited interesting rheological properties, very promising as compounds combining both UV filter capacity and texturizing properties for medical or cosmetic formulations. Regarding the second research axis, dextran, chitin, chitosan, and agarose were selected for their wide availability and unique properties in the field of biomaterials, especially for medical applications. The development of physical hydrogels by assembling these biopolymers relied on the development of protein cross-linkers named "bridges". Two libraries of four bridges, each with a specific affinity for a polymer, were designed by the association of two Carbohydrate Binding Modules (CBM) from enzymes that degrade or synthesize these polysaccharides, linked by a peptide sequence more or less flexible. These tailor-made proteins were recombinantly produced in E. coli and purified, and their affinities for their respective biopolymer was biochemically confirmed. Then, different hydrogels were made by assembling polysaccharides with these bridges, resulting in a visual difference in terms of texture and viscosity. These observations were supported by rheology and microscopy analyses. Notably, these dynamic hydrogels are shear-thinning and self-healing, which is very interesting for injectable hydrogels for delivering therapeutics. Overall, these first promising proofs of concept showed the potential of these novel bioinspired and innovative materials for different applications. The most interesting ones are envisioned in the field of healthcare. They could enable formulations that are respectful of both human health and ecosystems

This chapter provides a detailed investigation of where, when, and how photosynthesis originated and then evolved in non-eukaryotic organisms. It looks at some of the best accepted geological evidence for the earliest photosynthesis that comes from marine sedimentary deposits in rocks from the Buck Reef Chert in South Africa dated to 3.4 Ga. It also talks about rocks found in the Isua Greenstone Belt in Greenland, dating back from about 3.8 Ga, which harbour geochemical signatures consistent with photosynthesis. The chapter highlights the possibility that anoxygenic photosynthesis had already evolved well before 3 Ga, at a time when the Earth was still a highly anaerobic planet. It covers the two key evolutionary innovations required for the evolution of photosynthesis: first is the evolution of the reaction centre (RC) proteins, and second is a requirement for the evolution of biosynthetic pathways of chlorophylls and related pigments.

Antimicrobial compounds are groups consistent with the microorganisms that they could potentially act against bacteria or fungi. It is expected to kill microorganisms or inhibit their growth and activity. As the case of antimicrobial resistance increases, nature has been generous in providing compounds with the potential to treat various ailments and infectious diseases. Bacteria, fungi and plants are known to own a good list of antibacterial molecules. Although research has been carried out to reveal the antimicrobial potential of natural products, the significance of vast terrestrial and marine Animalia has gained momentum. Though the naturally available antimicrobial agents obtained from plants, animals and microbial sources are considered safe in comparison with synthetic molecules, the outbreak of pathogens needs exploration over and above the reported ones. As the synthetic antimicrobials soon become immune to pathogens, it makes emphasis on antimicrobials from novel origins that have a long duration of effectiveness. The marine environment houses a wide and taxonomically diverse species of algae, mollusks, sponges, corals and tunicates. These organisms have adapted to survive the infectious environment by producing pharmacologically active compounds of phlorotannins, fatty acids, polysaccharides, peptides, and terpenes that help in battling bacterial annexation. As marine algae provide considerable opportunities in antimicrobials, the optimization in the methodologies leading to extraction and purification plays a greater role in capturing the antimicrobial activity of the bioactive molecules. Though an outsized number of potential antimicrobial compounds from marine algae have been identified and isolated, the majority of those compounds are yet to be categorized and commercialized. Recent research in algae focused on “omics” where metagenomics, metatranscriptomics and metaproteomics are done to understand better pathway leading to the synthesis of various functional molecules.<br>