Influence of enhanced electrogenicity on anodic biofilm and bioelectricity production by a novel microbial consortium

Biofilms, flavins and pyocyanin have been identified as metabolites for species-specific electrogenicity. In this work, open circuit voltages (OCV) >500 mV earlier produced by electrogens in glucose-based media was used in confirming electrogens. Biofilms of test electrogens were grown on anodes of microbial fuel cells (MFCs) fed with glucose-based media. Electrogens used were anodophilic Enterobacter aerogenes 102, flavinogenic Bacillus sp. 101, Pichia kudriavzevii 103 and four pyocyanogenic Pseudomonads. Treatments with inhibitors (norspermidine, dichloro-diaminobenzene, and Raloxifene) negatively affected their electrogenicity. To enhance electrogenicity, increased anodic-biofilm was achieved by anode pretreatments with ultraviolet radiation and hydrogen peroxide, while pyocyanin-induced electrogenicity was enhanced by treatment with sophorolipds. Improved flavin yield and electrogenicity production was achieved by treatment with dimethyl-diaminobenzene. Bioelectricity production using metabolically-enhanced electrogens was carried out in a modified MFC and optimum yields were achieved using a consortium of all electrogens exposed to metabolic enhancements. Measurements of electrochemical potential showed improved electrogenicity in metabolically-enhanced consortium compared to the unenhanced consortium. Using eight MFCs in series, OCV value of 5000 mV was achieved, while parallel connections yielded increased current up to 6000 mA/m2. Electron microscopy showed well-developed biofilms formed by metabolically-enhanced consortium. EPS from consortium biofilm were also characterized using fourier transform-infrared (FT-IR) spectroscopy.

Automated summary

Biofilms, flavins, and pyocyanin have been identified as essential metabolites for specific electrogenicity in different species. This study focuses on optimizing biofilm growth and metabolic enhancements to improve bioelectricity production, resulting in enhanced electrogenicity in a consortium of all electrogens exposed to these enhancements.