Efficacies of Anaerobic Microbial Consortium for Starchy Lignocellulose Hydrolysis and Acidogenic Fermentation of Cassava Pulp

Cassava pulp (CP) is a starchy lignocellulose waste with starch granules entrapped within the cell wall. The enriched hydrolytic and acidogenic bacterial consortium (EHA) was established to break down the lignocellulosic structure and free starch granules during CP conversion into volatile fatty acids (VFAs). Consecutive batch subcultures were used to acclimatize the anaerobic lignocellulolytic microbial consortium for the anaerobic digestion of CP. Hydrolytic and acidogenic microorganisms in the anaerobic lignocellulolytic microbial consortium were then enriched by inhibiting methanogenic activity until a stable consortium, namely EHA4, was obtained. The performance of EHA4 in CP utilization was investigated based on different operating conditions, including CP concentration, inoculum-to-substrate ratio, and pH adjustment. The alpha diversity revealed that the acclimatization and enrichment decreased the consortium’s species richness, creating a solid community specializing in CP hydrolysis and acidification. EHA4 consortium used 100% of CP added within 4 days while producing high-yield VFAs dominated by butyrate and acetate. Clostridium was the dominant bacteria related to hydrolysis and acidification of CP found in EHA4 (41% relative abundance). The performance of EHA4 to degrade higher CP concentration showed a decrease in CP removal due to total VFAs inhibition while maintaining the pH recovered the CP utilization up to 4%. EHA4 is a potential microbial consortium for starchy lignocellulosic CP hydrolysis and acidification as the inoculum starter in biogas production in the future.