Enhancing surfactin production in Bacillus subtilis: Insights from proteomic analysis of nitrate-induced overproduction and strategies for combinatorial metabolic engineering

Improving Surfactin Production in Bacillus subtilis 168 by Metabolic Engineering

“…This might be due to inappropriate fermentation conditions leading to poor growth or to the toxicity of surfactin or organosilicon defoamer toward cells, which may have inhibited bacterial growth and surfactin synthesis. By optimising the fermentation medium and conditions alone, the OD 600 of B. subtilis ATCC 21332 reached 60, and surfactin production was increased from 335 mg/L to 5.3 g/L [18]. Therefore, optimising the fermentation conditions, including carbon sources, nitrogen sources, pH, inoculum size and metal ions by adding Fe nanoparticles [55] or EDTA-Fe 2+ [56], may be crucial for improving surfactin production in the future.…”

“…Overexpression of three putative lipopeptide transporters genes: yerP (endogenous), ycxA and krsE (heterologous) in B. subtilis THY-7 resulted in a 145%, 89% and 52% increase in surfactin production, respectively [31], and overexpression of endogenous yerP in B. subtilis 168 resulted in a 35.3% increase in surfactin production [21], demonstrating that YerP acts as the major surfactin exporter. Research by Xia et al, (2024) showed that preprotein translocase SecA, signal recognition particle receptor FtsY and cell division ATP-binding protein FtsE are also involved in the transport of surfactin in B. subtilis ATCC 21332 [18]. The present study used B. subtilis 168 as the parent strain.…”

“…However, low productivity of surfactin remains an important limiting Microorganisms 2024, 12, 998 2 of 17 factor in its industrial production [16,17]. For instance, combinatorial metabolic engineering of Bacillus subtilis ATCC 21332, including enhanced nitrate reduction, fatty acid hydroxylation, rational transporter engineering and feeding, yielded 14.4 g/L of surfactin, with the productivity of 0.6 g/L/h, the highest reported productivity to date [18]. Therefore, the development of microbial cell factories is crucial for its overproduction.…”

“…It has been recognised by the USA Food and Drug Administration (FDA) as a 'Generally Recognised as Safe' (GRAS) strain [20]. Therefore, B. subtilis is commonly used as a chassis for producing surfactin through metabolic engineering [18,21,22].…”