Enhancing biotin production in Bacillus subtilis: Overcoming native pathway limitations

Biotin is essential for metabolizing the three major nutrients and is vital for animal growth and development. Industrially, biotin production has relied on chemical synthesis, a method fraught with disadvantages including complex processes, environmental risks, and high costs. Consequently, researchers have increasingly recognized the benefits of biosynthesizing biotin. Native transcriptional regulation and metabolic bottlenecks restrict biotin production. Replacing the native promoter and bioO with the constitutive P₄₃ promoter, along with swapping the native birA for a non-regulatory variant from Mycobacterium tuberculosis, significantly upregulated biotin biosynthetic gene expression, effectively bypassing native transcriptional regulation. Subsequent strategies to bypass the inefficient native BioW included knocking out ydbM in the β-oxidation pathway—a potential pimeloyl-CoA degrader, expressing heterologous bioW genes, and introducing alternative pimeloyl-ACP biosynthetic pathways, collectively increasing biotin titers to 6.91 mg/L. This study demonstrates a multi-faceted approach to overcoming metabolic and regulatory barriers, providing a template for enhancing biotin production in B. subtilis, with implications for the broader field of microbial biotechnology.