Binding of Hg by bacterial extracellular polysaccharide: a possible role in Hg tolerance
| Autor: | Tamar Barkay, Jean Guezennec, Kimberly Cruz |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
030106 microbiology Mutant chemistry.chemical_element medicine.disease_cause Applied Microbiology and Biotechnology 03 medical and health sciences medicine Biomass Microbial mat Escherichia coli Extracellular polysaccharide Bacteria Escherichia coli K12 biology Polysaccharides Bacterial Sorption Exocellular polysaccharides Mercury General Medicine biology.organism_classification Mercury (element) 030104 developmental biology Biochemistry chemistry Mutation Toxicity Adsorption Tolerance Biotechnology |
| Zdroj: | Applied Microbiology And Biotechnology (0175-7598) (Springer), 2017-07, Vol. 101, N. 13, P. 5493-5503 |
| ISSN: | 1432-0614 0175-7598 |
| DOI: | 10.1007/s00253-017-8239-z |
| Popis: | Bacteria employ adaptive mechanisms of mercury (Hg) tolerance to survive in environments containing elevated Hg concentrations. The potential of extracellular polysaccharides (EPS) production by bacteria as a mechanism of Hg tolerance has not been previously investigated. The objectives of this study were to determine if bacterial EPS sorb Hg, and if so does sorption provide protection against Hg toxicity. Purified EPS with different chemical compositions produced by bacterial isolates from microbial mats in French Polynesian atolls and deep-sea hydrothermal vents were assessed for Hg sorption. The data showed that EPS sorbed up to 82% of Hg from solution, that this sorption was dependent on EPS composition, and that sorption was a saturable mechanism. Hg uptake capacities ranged from 0.005 to 0.454 mmol Hg/g for the different EPS. To determine if EPS production could alter bacterial Hg tolerance, Escherichia coli K-12 strains and their EPS defective mutants were tested by the disc inhibition assay. Mercury inhibited growth in a dose-dependent manner with wild-type strains having smaller (~1 mm), but statistically significant, zones of inhibition than various mutants and this difference was related to a 2-fold decline in the amount of EPS produced by the mutants relative to cell biomass. These experiments identified colanic acid and hexosamine as Hg-binding moieties in EPS. Together these data indicate that binding of Hg to EPS affords a low level of resistance to the producing bacteria. |
| Databáze: | OpenAIRE |
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