Genomic and transcriptomic insights into the cellulose-degrading mechanism of Bacillus subtilis DC-11 and its novel cellulose catabolic pathway.

The accumulation of silkworm excrement poses a significant environmental challenge, contributing to pollution and resource squandering. Unraveling the novel mechanism governing bacterial cellulose degradation represents a vital avenue for augmenting cellulose conversion efficiency. This study investigated the cultivation of Bacillus subtilis DC-11 with different carbon sources, utilizing transcriptome sequencing to identify metabolic pathways and differentially expressed genes (DEGs) closely related to cellulose degradation. Transcriptome analysis revealed 3,917 DEGs between the carboxymethyl cellulose sodium (CMC-Na) treatment group and the glucose-supplemented (GLU) control group. Compared to the control group, the CMC-Na treatment group exhibited upregulation of 942 genes, while 1,996 genes were downregulated. KEGG pathway analysis of DEGs indicated the involvement of that carbohydrate metabolism and phosphotransferase system (PTS) pathways in response to cellulose degradation. Real-time quantitative PCR validation confirmed that the expressions of key genes, namely ytoP, bglH, gmuD, licH, licC, ywbA, licA, gmuA, and gmuB, associated with the PTS pathway were consistent with the transcriptomics data. These results suggest that B. subtilis DC-11 degrades cellulose via carbohydrate metabolism and PTS pathways. This study offers new insights into the cellulose metabolism pathway of B. subtilis DC-11, providing both a theoretical basis and innovative strategies for the efficient degradation of cellulose.