Biomass and enzymatic activities of marine bacteria in the presence of multiple metals.

Marine environments are a repository for metals, and humans have enhanced this phenomenon over the years. Heavy metals are notoriously toxic due to their ability to biomagnify in the food chain and interact with cellular components. Nevertheless, some bacteria have physiological mechanisms that enable them to survive in impacted environments. This characteristic makes them important as biotechnological tools for environmental remediation. Thus, we isolated a bacterial consortium in Guanabara Bay (Brazil), a place with a long metal pollution history. To test the growth efficiency of this consortium in Cu-Zn-Pb-Ni-Cd medium, we measured the activity of key enzymes of microbial activity (esterases and dehydrogenase) under acidic (4.0) and neutral pH conditions, as well as the number of living cells, biopolymer production, and changes in microbial composition during metal exposure. Additionally, we calculated the predicted physiology based on microbial taxonomy. During the assay, a slight modification in bacterial composition was observed, with low abundance changes and little production of carbohydrates. Oceanobacillus chironomi, Halolactibacillus miurensis, and Alkaliphilus oremlandii were predominant in pH 7, despite O. chironomi and Tissierella creatinophila in pH 4, and T. creatinophila in Cu-Zn-Pb-Ni-Cd treatment. The metabolism represented by esterases and dehydrogenase enzymes suggested bacterial investment in esterases to capture nutrients and meet the energy demand in an environment with metal stress. Their metabolism potentially shifted to chemoheterotrophy and recycling nitrogenous compounds. Moreover, concomitantly, bacteria produced more lipids and proteins, suggesting extracellular polymeric substance production and growth in a metal-stressed environment. The isolated consortium showed promise for bioremediation of multimetal contamination and could be a valuable tool in future bioremediation programs.

Extracellular Polymeric Substances (EPS) produced by Streptomyces sp. biofilms: Chemical composition and anticancer properties.

The extracellular polymeric substances (EPS) have shown free radical scavenging and antitumor activity against both breast and colon cell lines. In this regard, actinobacteria have become an increasingly popular sources of EPS. Therefore, in this study four Streptomyces strains isolated from contaminated soil (M7, A5, A14 and MC1) were evaluated for determining its biofilm-forming capacity including under pesticide stress. In addition, chemical composition of EPS and its cytotoxic effects over 4T1 breast cancer cell and Caco-2 human tumor colon cells were evaluated. The results demonstrated that Streptomyces sp. A5 had the highest capability to develop biofilm more than other strains tested, even under pesticide stress. Moreover, this strain produced EPS with a total protein/total polysaccharide rate of 1.59 ± 0.05. On the other hand, cytotoxicity assays of EPS showed that Streptomyces sp. A5 display a higher toxic effect against 4T1 Breast cancer cells (96.2 ± 13.5 %), Caco-2 (73.9 ± 6.4 %) and low toxicity (29.9 % ± 9.1 %) against non-transformed intestinal cells (IEC-18). Data do not show cytotoxic effect relationship with biofilm-forming capabilities of strains, nor the chemical composition of EPS matrix. The gene that codes for polysaccharide deacetylase, parB-like and transRDD proteins, were identified. These results contribute to the knowledge about the variability of chemical composition and potential cytotoxic properties of EPS produced by Streptomyces biofilms. It proposes interesting future challenges for linking Streptomyces-based pesticide remediation technology with the development of new antitumor drugs.

Structural characterization and metal biosorptive activity of the major polysaccharide produced by Pseudomonas veronii 2E.

Pseudomonas veronii 2E, an autochthonous bacterium isolated from sediments associated to a high-polluted watershed, produces a complex matrix of exopolymers with carbohydrates as main components. In this work, four polysaccharides were isolated from the extracellular material. The major acidic polysaccharide named EPO2, was purified and its structure was elucidated using Matrix-assisted laser desorption/ionization and Electrospray ionization mass spectrometry, Infrared spectroscopy, Nuclear magnetic resonance spectroscopy and chemical treatments. This heteropolysaccharide consists in an α(1-4) glucan substituted with N-Acetylglucosamine residues and with a branching α-D-GlcpA-(1-3)-L-Fucp disaccharide. The biosorption capacity of EPO2 and of the whole exopolysaccharide to Pb(II), Zn(II), Cu(II) and Fe(II) was evaluated. EPO2 showed a remarkable sorption capacity for Fe(II) with an efficiency of 70% and for Zn(II) 39%. When the whole exopolysaccharide fraction was tested it showed a significantly lower metal sorption ability than purified EPO2 suggesting the involvement of the distinct acidic branching disaccharide in this interaction.

Characterization of the EPS from a thermophilic corrosive consortium.

Biofilm forming microorganisms are known to contribute to the corrosion of metallic materials, as they can attach to surfaces and influence the electrochemical behavior. Extracellular polymeric substances (EPS) produced by these microorganisms play a major role in adhesion and resistance of the biofilm, thus also contributing to corrosion. A better understanding of the composition of EPS could help mitigate the impact of bacterial mediated corrosion. Here, a preliminary characterization of the EPS from a thermophilic consortium isolated from a corroded airplane engine is presented. Analysis revealed five different monosaccharides, with predominance of glucose and manose, but also a significant amount of rhamnose. Glycosyl linkage analysis was also performed. On the lipid fraction, three types of fatty acids were found. The predominant protein found by peptide finger printing was S-Layer protein, related to bacterial adhesion. Morphological characterization of the biofilm forming consortium was carried using confocal and scanning electron microscopy.