Synergistic valorization: generating bioelectricity and high-protein animal feed from fermented crop residues

Abstract Background The management of agricultural waste (AW) poses a significant environmental challenge. This study explores the dual valorization of these wastes, harnessing their indigenous microbial communities for synergistic biotechnological applications in bioenergy and animal nutrition. Methods Using a combination of culture, biochemical assays, and 16 S rRNA/ITS sequencing, known and novel microorganisms within maize husk, sweet potato peel, wheat shaft, and sugarcane shaft substrates were identified. The proximate, mineral, and vitamin contents of the agro-wastes (AWs) were determined before and after 21 days of fermentation to determine substrate suitability for animal feed. A dual-chamber microbial fuel cell (MFC) was constructed to evaluate the bioelectricity generation potential. Results The sweet potato peel had the highest bacterial count at 3.8 × 10 4 CFU/ml, while the maize husk had the highest fungal load at 6.55 × 10 4 SFU/ml. Fermentation significantly increased the protein, mineral, and vitamin contents of the agrowastes after fermentation while reducing the fibre and carbohydrate contents. Notably, compared with the other substrates, the maize husk produced the highest voltage of 68 mV and current of 77 µA. Pichia kudriavzevii MN007220.1, Geotrichum candidum MK943778.1, Bacillus subtilis NR102783.2, and Lysinibacillus fusiformis KP419973.1 were identified in these AW substrates. Conclusions These findings underscore the dual potential of agricultural waste as a valuable source for bioelectricity generation and as a nutritious, digestible supplement for animal feed postfermentation. This highlights a viable ‘Waste-to-Wealth’ model for sustainable agricultural practices. Graphical Abstract