New protocol for the rapid quantification of exopolysaccharides in continuous culture systems of acidophilic bioleaching bacteria

Abstract

In this study, we investigate exopolysaccharide production by a bacterial consortium during the bioleaching of a cobaltiferrous pyrite. Whereas comparable studies have looked at exopolysaccharide production in batch systems, this study focuses on a continuous system comprising a series of four stirred bioreactors and reveals the difficulties in quantifying biomolecules in complex media such as bioleached samples. We also adapted the phenol/sulphuric acid method to take into account iron interference, thus establishing a new protocol for sugar quantification in bioleached samples characterised by low pH (1.4) and high iron concentration (2 g l(-1)). This allows sugar analysis without any prior sample preparation step; only a small amount of sample is needed (0.5 ml) and sample preparation is limited to a single filtration step. We found that free exopolysaccharides represented more than 80% of the total sugars in the bioreactors, probably because stirring creates abrasive conditions and detaches sugars bound to pyrite or bacteria and that they were produced mainly in the first two reactors where bioleaching activity was greatest. However, we could not establish any direct link between the measured exopolysaccharide concentration and bioleaching activity. Exopolysaccharides could have another role (protection against stress) in addition to that in bacterial attachment.

Biooxidation of Iron by Acidithiobacillus ferrooxidans in the Presence of D-Galactose: Understanding Its Influence on the Production of EPS and Cell Tolerance to High Concentrations of Iron

“…They are formed of proteins, sugars, lipids, nucleic acids and cell fragments whose composition and concentration may vary depending on microorganisms and environmental conditions (Wingender et al, 1999). The EPS fulfill different functions: reaction space for oxidation, forming an active and absorbing surface, favoring bacterial adhesion, helping the structural stabilization of the biofilm and forming a protective layer against biocides or other media inhibitors, among others (Wingender et al, 1999;Michel et al, 2009). EPS origin is mainly due to secretion processes and cell lysis, thus being accumulated on the surfaces of cells, or disseminated in the medium (Wingender et al, 1999).…”

Marine Invertebrates: Underexplored Sources of Bacteria Producing Biologically Active Molecules

“…Many authors clarified the significant contribute that exopolymer production gains in the organic carbon balance in the sea ice and in ice-water interface [172], and their biotechnological potential [171,173]. In addition, also reports on halophilic [174][175][176], alkaliphilic [177,178], and acidophilic [179][180][181][182] bacteria are available. Thus, the biodiversity of bacterial EPS producers is strongly related to the environment of origin.…”

Optimised methodology for carboxymethylation of (1→3)‐β‐d‐glucan from Yeast (Saccharomyces cerevisiae) and promotion of mechanical activation

“…The calibration curve of absorbance vs. concentration was prepared using glucose as standard. The total sugar content was expressed as the concentration of glucose equivalence by comparison with the calibration curve (Michel et al, 2009). The water solubility of carboxymethyl derivative was evaluated by measuring total sugar content of the supernatant.…”