Advanced lignocellulose bioprocessing for Aloe vera leaf rind through novel termite gut microbiome consortia for acetone butanol ethanol (ABE) production: metagenomics insights and process economic analysis

Consolidated bioprocessing (CBP) of lignocellulosic biomass (LCB) using microbes simplifies the process, eliminates enzyme cost and reduces the overall processing expenses. In this regard, termite gut, a potent reservoir of microbial symbionts produces various lignocellulolytic enzymes which acts synergistically to degrade LCB. However, the effectiveness of adapting the microbes with LCB for improved lignocellulolytic enzyme secretion and substrate degradation has been overlooked. Hence, in this study adaptive laboratory (ALE) of termite gut isolates was performed with various substrates such as saw dust (SD) and Aloe vera leaf rind (AVLR) under different conditions. Among the consortia, enriched termite consortium (ETC-3) showed the highest degradation of lignin (51.86 ± 2.03 %, w/w), hemicellulose (29.27 ± 1.29 %, w/w) and cellulose (41.97 ± 2.99 %, w/w) with maximum specific enzyme activities. High throughput sequencing revealed the significant enrichment of Proteobacteria (88.95 %) and Ascomycota (99.94 %) groups in ETC-3. Further, the efficiency of ETC-3 in consolidated pretreatment and bioprocessing (CPBP) and CBP of AVLR towards acetone, butanol and ethanol (ABE) production was studied. Compared to the CPBP, CBP resulted in 1.6-fold higher glucose yield which subsequently enhanced the butanol yield (7.97 ± 0.40 g/L). Finally, cost benefit analysis ensured the economic feasibility of process strategies for AVLR valorization.