Striving to understand bacterial roles within an electrogenic community

M. BELÉN PRADOS

Marsella

Conferencia; Seventh International Symposium on Environmental Biotechnology and Engineering; 2023

Electrogenic microorganisms have the capability of respiring solid extracellular compoundsand electrodes. This faculty has encouraged the development of environmental and industrialprocesses called Bioelectrochemical Systems (BES). When BES are inoculated with a naturalsource, electrogenic bacterial communities are usually recovered from BES electrodes. Theperformance of the BES is affected by the electrogenic members of the inoculum source.However, in most cases, the interactions between the members of the community areunknown.Through a combination of microbiological and electrochemical techniques, we selected anelectrogenic community (RE480) from a polluted river sediment (río Reconquista, Argentina),which included the genera Shewanella, Aeromonas, Pseudomonas, Enterobacter andLachnclostridium. In this work, we attempted to understand the roles of the species in thecommunity. Two bacterial strains were isolated employing classical microbiological tools(selective liquid and semi-solid media). As determined by 16S gene sequencing, these strainswere highly related to Shewanella xiamenensis and Aeromonas sp.. Cell morphology, growthand Fe(III) reduction were studied in aerobic and anaerobic media, in the presence of differentcarbon sources (acetate, pyruvate and glucose) and electron acceptors (fumarate, Fe(III)). Theelectrochemical characteristics of the strains were studied in BES. The BES were sterileanaerobic glass single-chamber cells with three electrodes: a solid graphite rod (workingelectrode), a platinum wire (counter electrode) and a Ag/AgCl as reference electrode. TheBES were filled with culture media with acetate-Na as carbon source, no electron acceptorother than the electrode was provided. Each BES was inoculated with a specific bacterialculture and operated at constant potential (240 or 480 mV vs Ag/AgCl) and temperature(30°C) in anaerobiosis.