Transcriptomic analysis of peptide production from solid-state fermented soybean meal by Bacillus subtilis SBM_1

Area of Science:

• Microbiology and Biotechnology
• Biochemistry
• Molecular Biology

Background:

• Microbially fermented feeds enriched with peptides offer potential for antibiotic-free feed development.
• Understanding peptide generation mechanisms during solid-state fermentation (SSF) is key for process optimization.
• This study investigates transcriptional changes in Bacillus subtilis SBM_1 during SSF to elucidate peptide production mechanisms.

Purpose of the Study:

• To investigate the transcriptional changes in Bacillus subtilis SBM_1 during SSF.
• To explore the mechanisms underlying peptide production in B. subtilis SBM_1.
• To identify key genes and pathways involved in peptide synthesis and secretion.

Main Methods:

• Solid-state fermentation (SSF) of Bacillus subtilis SBM_1.
• Transcriptional analysis using differential gene expression.
• Bioinformatic analysis of enriched pathways and gene clusters.

Main Results:

• Differentially expressed genes (DEGs) were enriched in metabolism, ABC transporters, and amino acid biosynthesis pathways.
• Genes for extracellular protease synthesis and secretion were up-regulated, facilitating soybean protein hydrolysis.
• B. subtilis SBM_1 synthesized and secreted both ribosomally synthesized and post-translationally modified peptides (RiPPs) and non-ribosomal peptides (NRPs), including amylocyclicin and subtilin.

Conclusions:

• B. subtilis SBM_1 synthesizes peptides and secretes extracellular proteases during SSF to produce peptides from soybean proteins.
• Synthesized peptides are exported via the ABC transporter pathway, leading to peptide accumulation.
• These findings support the use of fermented feeds for antibiotic-free animal nutrition.