Metatranscriptomic profiling reveals microbial succession and adaptation strategies during long-term lignocellulose degradation

Abstract

Lignocellulosic biomass is an abundant and renewable feedstock, promising for biofuel production and other industrial applications; however, it presents numerous challenges due to its complex structure. Alternatively, microbial systems naturally possess robust mechanisms capable of efficiently degrading this material. In this study, we investigated the functional and compositional changes of a microbial community in the early and late stages of adaptation to a lignocellulosic substrate using a metatranscriptomic approach. The results revealed a transition in the contribution of major phyla associated with degradation, with Bacteroidota decreasing from approximately 18 % to less than 1 % of the relative abundance of expressed transcripts, while Bacillota increased from approximately 3 % to more than 27 % in the late stage. In parallel, a proportional increase in CAZymes related to cellulose and hemicellulose breakdown was revealed in the late stage, suggesting greater cellulolytic and hemicellulolytic activity at later time points. Notably, a substantial fraction of transcripts identified as key lignocellulases (>30 %) were affiliated with the genus Paenibacillus (phylum Bacillota), highlighting its significant role in biomass degradation throughout the adaptation period. These findings highlight how prolonged exposure to lignocellulosic substrates selectively increases microbial taxa and enzymatic pathways critical for efficient biomass conversion. Such results are relevant for the development of biotechnological solutions such as enzymatic bioprospecting and industrial optimization of microbial lignocellulose processing, as well as for the development of strategies for the enrichment of high-performance degraders through targeted cultivation.