The enhancement of electricity generation using cellulose based on ternary microbial consortium

Abstract

ABSTRACTCooperation between microorganisms is crucial to design an efficient inoculum for enhancing the electricity-producing ability of carboxymethyl cellulose (CMC) fed bioreactors. In the present study, the influence of microbial mutualistic interactions and electricity generation capability were investigated by designing several co-culture and ternary culture systems. It was found that a ternary culture system ofCellulomonasLsc-8,Bacillus subtilisC9 andGeobacter sulfurreducensPCA was used to efficiently convert cellulose into electricity. The maximum current density of 796 ± 30 µA·cm-2were achieved by the ternary culture, which were much higher than thatGeobacter sulfurreducensPCA using acetate and co-culture systems to utilize CMC in bioreactors, respectively. In this consortium,CellulomonasLsc-8, andBacillus subtilisC9 simultaneously digested CMC to produce acetate and secreted riboflavin as an electron shuttle;Geobacter sulfurreducensPCA utilized acetate to generate electricity. The introduction ofBacillus subtilisC9 further promoted the degradation of CMC and secreted more riboflavin to enhance electricity generation of the ternary culture. This work suggested that the synergistic interaction between interspecies in microbial consortia is emergent in designing specific community for achieving maximum power generation using CMC as substrate. This research shows new insight into the design of more efficient, stable, and robust microbial consortia applicable in waste treatment and power generation.IMPORTANCEMicrobial fuel cells (MFCs) may benefit from microbial consortia that efficiently convert carbon sources to electricity. A key challenge with this system is how to manage microbial community assembly to maximize electricity generation. Herein, we constructed and tested a three-species microbial consortium to enhance conversion of cellulose to electricity.CellulomonasLsc-8 andBacillus subtilisC9 efficiently converted cellulose to acetate (electron donor) and riboflavin (electron shuttle), which enabledGeobacter sulfurreducensto generate electricity. This study laid the foundation for design of more efficient, stable, and robust microbial consortia for waste treatment and energy applications.