Protocol for bioelectrochemical enrichment, cultivation, and characterization of extreme electroactive microorganisms

Abstract

Summary Electroactive microorganisms (EAMs) are a group of microbes that can access solid extracellular electron donors or acceptors via extracellular electron transfer processes. EAMs are useful in developing various microbial electrochemical technologies. This protocol describes the use of bioelectrochemical systems (BESs) to enrich EAMs at the cathode from an extreme haloalkaline habitat. It also provides information for a detailed characterization of enriched cathodic biofilms via various cross-disciplinary techniques, including electrochemical, analytical, microscopic, and gene sequencing techniques. For complete details on the use and execution of this protocol, please refer to Chaudhary et al. (2021) .

The Bioaugmentation of Electroactive Microorganisms Enhances Anaerobic Digestion

“…The methane production through the DIET of EAMs may be vital to addressing the unresolved intrinsic issues of anaerobic digestion [26,44,45]. The EAMs can be enriched on the surface of polarized electrodes placed in anaerobic digesters [8,46,47]. However, methane production through DIET becomes meaningful in improving anaerobic digestion only in the anaerobic digester with polarized electrodes of sufficient area.…”

Geoalkalibacter halelectricus SAP‐1 sp. nov. possessing extracellular electron transfer and mineral‐reducing capabilities from a haloalkaline environment

“…To check the capabilities to respire both soluble and insoluble electron acceptors via EET, the isolated strain was anaerobically cultivated on a modified M9 medium supplemented with soluble (fumarate and sulfate [SO 4 2− ]) and insoluble (mineral oxides, namely, ferric oxide [Fe 2 O 3 ] and manganese oxide [MnO 4 ]), as the sole electron acceptors. For sulfate experiments, both reactant (sulfate [SO 4 2− ]) and reduced product (sulfide [S 2− ]) were analysed using turbidimetric and methylene blue methods, respectively with a UV–Vis spectrophotometer (WTW PhotoLab® 7600) (Rice et al, 2012; Singh et al, 2022a, 2022b). Acetate served as the sole source of carbon and electrons in all but different substrate utilization tests.…”

“…Mn 4+ 2À ]) and reduced product (sulfide [S 2À ]) were analysed using turbidimetric and methylene blue methods, respectively with a UV-Vis spectrophotometer (WTW PhotoLab ® 7600) (Rice et al, 2012;Singh et al, 2022aSingh et al, , 2022b. Acetate served as the sole source of carbon and electrons in all but different substrate utilization tests.…”

“…The EET capabilities, that is, electroactivity of SAP-1 was tested by checking its capability to respire on a solid-state electron acceptor, that is, electrode via the electrochemical cultivation approach (Chiranjeevi & Patil, 2020;Singh et al, 2022aSingh et al, , 2022b. On inoculation of the triplicate bioelectrochemical reactors with SAP-1 culture, the bioelectrocatalytic current response associated with the acetate oxidation linked to the electrode reduction process was observed.…”