New protocol for the rapid quantification of exopolysaccharides in continuous culture systems of acidophilic bioleaching bacteria |
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Authors: | Caroline Michel Claire Bény Fabian Delorme Laurence Poirier Pauline Spolaore Dominique Morin and Patrick d’Hugues |
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Institution: | (1) BRGM, EPI/ECO, 3 avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 2, France;(2) BRGM, MMA/MIN, 3 avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 2, France |
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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. |
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Keywords: | Exopolysaccharides Bioleaching Laboratory-scale continuous bioreactors Acidophilic bacterial consortium Modified phenol/sulphuric acid method ATR-FTIR |
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