Application of organic waste glycerol to produce of crude extracts of bacterial cells and microbial hydrogenases - the anode enzymes of bio-electrochemical system.

Abstract

Glycerol is an organic waste material, which can be used for production of microbial biomass and consequently serving valuable biocatalysts promoting generation of electric current in microbial fuel cell (MFC). [NiFe]-Hydrogenases (Hyd) of Escherichia coli and Ralstonia eutropha may be applied as potential anode biocatalysts in MFC. In this study, E. coli K12 whole cells or crude extracts and R. eutropha HF649 synthesizing Strep-tagged membrane-bound Hyd (MBH) were evaluated, as anode enzymes in the bioelectrochemical system. The samples were immobilized on the sensors with polyvinyl acetate support. Mediators like ferrocene and its derivatives (ferrocene-carboxy-aldehyde, ferrocene-carboxylic acid, methyl-ferrocene-methanol) were engaged. The maximal level of bioelectrocatalytic activity of Hyds was demonstrated at 500 mV voltage. Depending on the mediator and biocatalyst current strength varied from 5 μA to 42 μA. Introduction of ferrocene-carboxylic acid enhanced current strength: moreover, the current flow was directly correlated with H2 concentration. The maximal value (up to 150 μA) of current strength was achieved with a two-fold hydrogen supply. It may be inferred that Hyds are efficiently produced by E. coli and R. eutropha grown on glycerol, while ferrocene derivatives act as agents mediating electrochemical activity of Hyds.

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Identifiers

DOI

10.1093/femsle/fnaa056

Journal

FEMS Microbiology Letters

Year

2020