Bacterial extracellular polymeric substance (EPS): A carrier of heavy metals in the marine food-chain

Abstract

The ecological implications of metal binding properties of bacterial EPS and its possible role in the bioaccumulation of pollutants in the marine food-chain was investigated using a partially purified and chemically characterized microbial EPS isolated from a species of Marinobacter. Various factors influencing metal sorption by the EPS including the influence of initial metal concentrations, incubation time, pH and sodium chloride concentrations on binding of lead (Pb2+) and copper (Cu2+) were evaluated. The bacterial EPS selectively bound more amount of Cu2+ per mg of EPS than Pb2+. Both copper and lead were sorbed more at near neutral pH than acidic pH. The sorption of Cu2+ increased with increasing copper concentration. The estimated maximum binding ability (MBA) of the EPS was 182 nmol copper and 13 nmol lead mg(-1) EPS. However, the sorption of these metals decreased with the increase in sodium chloride concentration. Furthermore, up to 35% of 14C-labeled Marinobacter was ingested by a benthic polychaete Hediste diversicolor. On an average, 29% of the ingested EPS was absorbed into tissues and 49% of the EPS was respired. It was apparent that the animals used the EPS as a source of energy and nutrition. The labile nature of the bacterial EPS and its ability to bind heavy metals might route the bound metals through the marine food chain, thereby transferring and aiding bioaccumulation of metal pollutants in the higher trophic animals.

Identification of a c-di-GMP-Regulated Polysaccharide Locus Governing Stress Resistance and Biofilm and Rugose Colony Formation in Vibrio vulnificus

“…CPS mediates resistance of bacteria to complement-mediated bacteriolysis and phagocytosis (31,34). EPS possesses both adsorptive and adhesive properties (6,42,89). EPS has also been shown to impart a wrinkled, raised look to the normally flat, featureless appearance of wild-type cells.…”

Implications of Extracellular Polymeric Substance Matrices of Microbial Habitats Associated with Coastal Aquaculture Systems

“…Copper and lead bacterial EPS complexes were given to the benthic polychaete Hediste diversicolor as feed. EPS were shown to serve as effective natural organic ligands binding dissolved copper and lead at a range of concentrations and pH values, suggesting this route can concentrate metals through the marine food chain [132]. Other cultured benthic deposit-feeders such as sea cucumbers, may also concentrate metals, although this may vary given that various factors influence metal sorption by EPS, including metal concentration, incubation time, pH and salinity of the medium.…”

Quantifying biostabilisation effects of biofilm-secreted and extracted extracellular polymeric substances (EPSs) on sandy substrate

“…The microbes in biofilms live in a self-formed matrix of gluelike and hydrated extracellular polymeric substances (EPSs) such as polysaccharides (often 40-95 %), proteins (up to 60 %) and minor amounts of acids, lipids and biopolymers (Decho, 1990;Flemming, 2011;Gerbersdorf et al, 2011). The ecosystem functions of EPSs in sediment particle aggregation, increasing sediment stability, altering chemical properties to enable contaminant release or adsorption and providing a food source for invertebrates are well established for marine environments (Decho, 1990;Passow, 2002;Bhaskar and Bhosle, 2006;Paterson et al, 2008) but remain less well understood for freshwater systems (Gerbersdorf et al, 2011). The ability of biofilms to stabilise sediment Published by Copernicus Publications on behalf of the European Geosciences Union.…”