Improvement of surfactin production in Bacillus subtilis using synthetic wastewater by overexpression of specific extracellular signaling peptides, comX and phrC

Abstract

Surfactin is a biological surfactant with numerous potential applications. In this study, Bacillus subtilis was engineered to improve surfactin production by the activation of two competence-stimulating pheromones, ComX and competence and sporulation factor (CSF) to stimulate the transcription of srfA operon. Both signaling factors, encoded by comX and phrC, were successfully overexpressed and subsequently increased surfactin production. Surfactin produced by engineered strains showed functional groups similar to the commercially available surfactin analyzed via Fourier transform infrared spectroscopy (FTIR). Surfactin production in the B. subtilis (pHT43-comXphrC) strain was 6.4-fold greater than in the wild strain, with approximately 135.1 mg/L surfactin produced after 48 h cultivation. To reduce the production costs of surfactin, synthetic wastewater was used, from which the B. subtilis (pHT43-comXphrC) strain produced approximately 140.2 mg/L surfactin. The results obtained demonstrated the production of surfactin from synthetic wastewater, which is beneficial in lowering the overall production costs.

In situ enhancement of surfactin biosynthesis in Bacillus subtilis using novel artificial inducible promoters

“…Surfactin is natively synthesized by surfactin synthase (SrfA), a seven module non‐ribosomal peptide synthase (NRPS), and then transported outside the cells during fermentation (Roongsawang et al, ; Tapi et al, ). In light of this mechanism, previous studies have applied multiple genetic strategies to various B. subtili s species, including promoter replacement (Bechet et al, ; Fickers et al, ; Sun et al, ), and overexpression of specific extracellular signaling peptides (Jung et al, ), assistant proteins and surfactin transporters (Li et al, ; Sekhon et al, ). The maximum surfactin titers achieved through these approaches were 3.87, 0.14, and 2.13 g/L, respectively.…”

Direct Bio-Utilization of Untreated Rapeseed Meal for Effective Iturin A Production by Bacillus subtilis in Submerged Fermentation

“…If the production costs of these cyclic lipopeptide antibiotics become competitive with the synthetic chemical pesticides, their industrial use might be expected to grow tremendously in the coming decade [7]. In order to achieve this goal, recent efforts have been focused on the reduction of lipopeptide antibiotics production costs through improving the yield and utilization of low-cost feedstocks, such as soybean curd residue [8], soybean and sweet potato residues [9], cassava flour wastewater [10], [11], synthetic wastewater [12] and waste soybean oil [13]. However, no reports comparing the production performance of lipopeptide by using these feedstocks with that by using common industrial fermentation raw materials have been found.…”

Genome and transcriptome analysis of surfactin biosynthesis in Bacillus amyloliquefaciens MT45

“…However, these efforts have not yet successfully generated commercially viable and profitable surfactin production and will be unable to do so unless the yield of the final product from producer organisms is naturally high2. Therefore, surfactin producers demonstrating enhanced productivity per cell were constructed after screening for overproducing mutants or establishing genetically modified strains2122. For example, recombinant strains characterized by promoter exchange of the srfA operon were constructed to eliminate surfactin synthesis through quorum sensing and constitutively produce surfactin23.…”

“…For example, recombinant strains characterized by promoter exchange of the srfA operon were constructed to eliminate surfactin synthesis through quorum sensing and constitutively produce surfactin23. Unfortunately, these attempts have met with limited success, and it remains difficult to meet the needs of industrial applications, reflecting the complex intrinsic regulatory network underlying srfA expression2223.…”