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Engineering Streptomyces diastatochromogenes 1628 to increase the production of toyocamycin

Toyocamycin (TM) shows antifungal activity and can be used to treat plant diseases. TM is produced by Streptomyces diastatochromogenes 1628, but the production rate is always very low. Recently, the gene toyG was cloned; however, nothing was known about the influence of toyG on TM production. In this study, the rational combined co‐expression of toyG with frr encoding a ribosome recycling factor and vgb encoding Vitreoscilla hemoglobin was performed. Introduction of these genes in double‐ or triple‐combination into strain S. diastatochromogenes 1628 led to greatly increased TM production. Transcription analysis revealed that higher TM production in the constructed recombinant strains resulted from an increase in transcriptional levels of toyG gene. At the end, among all these different recombinant strains, the strain S. diastatochromogenes 1628‐VGF, harboring vgb, frr, and toyG placed under the control of PermE*, exhibited the largest increase in TM production. Notably, TM produced by S. diastatochromogenes 1628‐VGF reached the highest level of 319.2 mg/L at 72 h, while TM yield of the original strain 1628 was 147.1 mg/L at 84 h. The high‐yield, energy‐saving strain 1628‐VGF constructed in this study shall be beneficial for the industrial production of TM.