Adaptive evolution of thermophilic microbial consortia enables efficient cassava pulp degradation
Cassava pulp (CP) is an abundant agro-industrial waste containing high residual starch entrapped within a complex lignocellulosic matrix. Efficient biological conversion of CP requires the coordinated action of diverse hydrolytic enzymes. This study aimed to develop thermophilic microbial consortia for consolidated bioprocessing of CP. Through adaptive laboratory evolution at 50 degrees C, microbial consortia with high CP-degrading activity were successfully enriched from compost and manure inocula. The top-performing consortium (F3) achieved 92.6% starch removal after eleven successive transfers. Amplicon sequencing of the 16S rRNA gene revealed a reduction in community diversity, driven by a strong selective pressure that favored thermophilic Firmicutes, particularly Bacillus and Clostridium species. A total of 12 bacterial strains were subsequently isolated from the enriched consortia. Functional characterization demonstrated distinct, substrate-dependent enzyme production profiles among the isolates. Notably, Bacillus sp. isolate CP12 exhibited the highest CP degradation efficiency (74.9%), despite producing only moderate levels of amylase, likely due to the synergistic secretion of accessory cell wall-degrading enzymes (xylanase and pectinase). These findings highlight that maximal bioconversion of complex biomass relies on functional cooperation rather than the hyper-production of a single enzyme. The functionally defined isolates obtained in this study provide essential modular building blocks for the future rational design of synthetic thermophilic consortia for sustainable biomass valorization.