Bioaugmentation with Bacillus subtilis and Cellulomonas fimi to enhance the biodegradation of complex carbohydrates in MFC-fed fruit waste

The present study aimed to investigate the biodegradation of waste fruit by microbial fuel cells (MFC) when employing bioaugmentation of polysaccharides degrading bacterial strains and in-situ produced fungal mash. Bioaugmentation with Cellulomonas fimi and Bacillus subtilis both separately and in combination resulted in high chemical oxygen demand removal, high carbohydrates removal, and high solids removal efficiency, which is a slow process otherwise. The results revealed that Cellulomonas fimi alone achieved 60% and 17% higher chemical oxygen demand removal in 24 and 48 h respectively, than control treatment sludge. Cellulomonas fimi alone and in combination with Bacillus subtilis displayed an efficient carbohydrates removal of >90%. Fungal pre-treatment filtered also displayed high organics removal, the coulombic efficiency, however, remained 144% lower than Cellulomonas fimi and Bacillus subtilis augmented reactor. The presented results demonstrate that microbes are crucial for effective functioning of MFC, and high organics removal can be achieved with the use of right mi-crobial cultures.

Automated summary

The present study investigated the use of bioaugmentation and in-situ fungal mash in microbial fuel cells (MFC) for the biodegradation of waste fruit. The results showed that bioaugmentation with Cellulomonas fimi and Bacillus subtilis separately and in combination resulted in high removal of chemical oxygen demand, carbohydrates, and solids. Cellulomonas fimi alone achieved significantly higher chemical oxygen demand removal compared to the control treatment. Efficient carbohydrates removal (>90%) was observed with Cellulomonas fimi alone and in combination with Bacillus subtilis. Fungal pre-treatment also showed high organics removal, but with lower coulombic efficiency compared to the Cellulomonas fimi and Bacillus subtilis augmented reactor.