Enhanced production of iturin A in Bacillus amyloliquefaciens by genetic engineering and medium optimization

• Published in: Process biochemistry (1991) Vol. 90; pp. 50 - 57
• Main Authors: Xu, Yuxiang, Cai, Dongbo, Zhang, Hong, Gao, Lin, Yang, Yong, Gao, Jiaming, Li, Yanyan, Yang, Chunlei, Ji, Zhixia, Yu, Jun, Chen, Shouwen
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.03.2020; Elsevier BV
• Subjects: AbrB; Antifungal activity; Bacillus amyloliquefaciens; Biological control; Brown spot; Fermentation; Fungicides; Genetic engineering; Industrial production; Iturin A; Leafspot; Medium optimization; Optimization; Plant growth; Promoter replacement; Tobacco; Transcription; Iturin A; Bacillus amyloliquefaciens; Promoter replacement; Medium optimization; AbrB
• ISSN: 1359-5113; 1873-3298
• DOI: 10.1016/j.procbio.2019.11.017

[Display omitted] •The promoter PbacA was proven as the most efficient promoter for iturin A synthesis.•Deletion of regulator gene abrB improved iturin A synthetase gene cluster transcription and iturin A production.•The titer of 2013.43 mg/L iturin A was produced by optimizing fermentation medium formulas, increased by 392.15 %.•Enhancing the synthetic capability of iturin A was beneficial for the suppression of A. alternate. Brown spot disease, caused by Alternaria alternate, is one of the most destructive leaf spot diseases that made a major impact on tobacco growing. Biocontrol has attracted increasing attentions as its features of environmental friendship, promoting plant growth, etc. Iturin A, with broad spectrum antifungal activity, is a kind of biosurfactant that mainly produced by Bacillus. In this study, the promoter of iturin A synthetase cluster of Bacillus amyloliquefaciens HZ-12 was respectively replaced by promoters P43, PbacA, PsrfA and Pylb, our results implied that transcriptional level of gene ituD and iturin A titer showed consistent change trends, and PbacA was proven as the most efficient promoter, iturin A titer of which reached 950.08 ± 19.43 mg/L. Furthermore, regulator gene abrB was deleted to release the repression effect of AbrB on PbacA, ituD transcriptional level and iturin A titer were increased by 133.25 % and 20.88 %, respectively. Then, the maximum iturin A titer reached 2013.43 ± 32.86 mg/L by optimizing fermentation medium, increased by 392.15 % compared to the original (408.97 ± 21.35 mg/L). Finally, our results demonstrated that enhancing iturin A synthetic capability benefited the suppression of A. alternate. Collectively, this study provided a promising strain with an efficient fermentation medium for large-scale industrial production of iturin A.