Overcoming the Bottlenecks of Cellulose Utilization in Microbial Fuel Cells via Bioaugmentation Strategy with Cellulose‑Degrading Isolates

Although cellulosic biomass was among the most abundant substrates for producing renewable energy, its energy recovery in microbial fuel cells (MFCs) was often relatively low, owing to its low biodegradability. Here, the effect of bioaugmentation of three cellulose-degrading bacterial isolates (Acinetobacter tandoii, Brevundimonas bullata, and Micrococcus endophyticus) on MFCs efficiency was evaluated. Bioaugmented MFC with Acinetobacter tandoii strain showed the highest power densities (373 mW m-3) compared with nonbioaugmented MFC (240 mW m-3), associated with near-complete cellulose biodegradation. The results reveal that the bioaugmentation approach shaped the microbial community structure with the emergence of several phylotypes that were closely related to cellulose fermentation (Firmicutes and Bacteroidetes) and anode respiration (Proteobacteria), establishing a syntrophic partnership among cellulose-fermenting bacteria and electrochemically-active bacteria (EAB). In conclusion, our results confirm that the performance of mixedculture MFCs fed with complex substrates (e.g., cellulose) could be improved by the bioaugmentation approach of fermenting isolates.