title: A new strategy for strain improvement of Aurantiochytrium sp. based on heavy-ions mutagenesis and synergistic effects of cold stress and inhibitors of enoyl-ACP reductase.
abstract: Developing a strain with high docosahexaenoic acid (DHA) yield and stable fermenting-performance is an imperative way to improve DHA production using Aurantiochytrium sp., a microorganism with two fatty acid synthesis pathways: polyketide synthase (PKS) pathway and Type I fatty acid synthase (FAS) pathway. This study investigated the growth and metabolism response of Aurantiochytrium sp. CGMCC 6208 to two inhibitors of enoyl-ACP reductase of Type II FAS pathway (isoniazid and triclosan), and proposed a method of screening high DHA yield Aurantiochytrium sp. strains with heavy ion mutagenesis and pre-selection by synergistic usage of cold stress (4°C) and FAS inhibitors (triclosan and isoniazid). Results showed that (1) isoniazid and triclosan have positive effects on improving DHA level of cells; (2) mutants from irradiation dosage of 120Gy yielded more DHA compared with cells from 40Gy, 80Gy treatment and wild type; (3) DHA contents of mutants pre-selected by inhibitors of enoyl-ACP reductase of Type II FAS pathway (isoniazid and triclosan)at 4°C, were significantly higher than that of wild type; (4) compared to the wild type, the DHA productivity and yield of a mutant (T-99) obtained from Aurantiochytrium sp. CGMCC 6208 by the proposed method increased by 50% from 0.18 to 0.27g/Lh and 30% from 21 to 27g/L, respectively. In conclusion, this study developed a feasible method to screen Aurantiochytrium sp. with high DHA yield by a combination of heavy-ion mutagenesis and mutant-preselection by FAS inhibitors and cold stress.
authors.affiliation: Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China; Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yu-Rong
authors.initials: YR
authors.lastname: Cheng
authors.affiliation: Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China. Electronic address: sunzj@qibebt.ac.cn.
authors.forename: Zhi-Jie
authors.initials: ZJ
authors.lastname: Sun
authors.affiliation: Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China; Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong, China.
authors.forename: Gu-Zhen
authors.initials: GZ
authors.lastname: Cui
authors.affiliation: Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China; Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong, China.
authors.forename: Xiaojin
authors.initials: X
authors.lastname: Song
authors.affiliation: Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China; Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China; Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong, China. Electronic address: cuiqiu@qibebt.ac.cn.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Cui
mesh_terms: D003080:Cold Temperature; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000096:biosynthesis*; D050745:Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific) / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D054889:Fatty Acid Synthase, Type II / Q000037:antagonists & inhibitors; D005285:Fermentation; D007477:Ions; D007538:Isoniazid / Q000494:pharmacology; D016296:Mutagenesis; D058009:Stramenopiles / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D013312:Stress, Physiological; D014260:Triclosan / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D007477:Ions; D004281:Docosahexaenoic Acids; D014260:Triclosan; D050745:Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific); D054889:Fatty Acid Synthase, Type II; D007538:Isoniazid
keywords: Aurantiochytrium sp.; Coldstress; Heavy-ions mutagenesis; Isoniazid; Triclosan