Analysis of ascomycin production enhanced by shikimic acid resistance and addition in Streptomyces hygroscopicus var. ascomyceticus

• Published in: Biochemical engineering journal Vol. 82; pp. 124 - 133
• Main Authors: Qi, Haishan, Zhao, Sumin, Wen, Jianping, Chen, Yunlin, Jia, Xiaoqiang
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.01.2014; Elsevier
• Subjects: Biological and medical sciences; Biosynthesis; Biotechnology; Enzyme activity; Fermentation; Fundamental and applied biological sciences. Psychology; Immunosuppressant; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Optimization; Shikimic acid; Streptomyces hygroscopicus; Immunosuppressant; Biosynthesis; Enzyme activity; Fermentation; Shikimic acid; Optimization; Streptomyces hygroscopicus; Streptomycetaceae; Actinomycetales; Resistance; Enzymatic activity; Production; Bacteria; Actinomycetes
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2013.11.006

•A mutant SA68 was achieved by shikimic acid enduring selection model.•Ascomycin production reached the peak of 450mg/L with shikimic acid addition.•Pathways were identified providing key metabolites for higher ascomycin production. Shikimic acid resistance and addition to enhance immunosuppressant ascomycin production were investigated in this study. A shikimic acid resistant strain SA68 was obtained with ascomycin production of 330mg/L, displaying approximately 22% increment compared with the parental strain FS35 (270mg/L). Under the optimal condition of 3g/L shikimic acid added at 24h, ascomycin production was further increased by 36%, reaching 450mg/L. To get deep insights into the effects of shikimic acid resistance and addition on ascomycin biosynthesis, fermentation properties, enzymes activities, metabolites and genes transcriptional levels were analyzed and evaluated. The potential targets were revealed for higher ascomycin production, which were the amplification of carbon flux toward shikimic acid by enhancing 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase (DAHPS) activities and eliminating the feedback inhibition of aromatic amino acids on DAHPS activities, and the elevation of FkbO activities by amplifying fkbO gene to increase the flux of shikimic acid to chorismic acid further to 4,5-dihydroxycyclohex-1-enecarboxylic acid in Streptomyces hygroscopicus var. ascomyceticus. The results indicated that the developed methods would be helpful for ascomycin large scale fermentation. Moreover, the potential targets revealed in this study are valuable to engineer the higher-yield ascomycin-producing strain, as well as other analogous macrolide compounds-producing strains.