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

• Published in: Enzyme and microbial technology Vol. 93-94; pp. 182 - 190
• Main Authors: Cheng, Yu-rong, Sun, Zhi-jie, Cui, Gu-zhen, Song, Xiaojin, Cui, Qiu
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2016
• Subjects: Aurantiochytrium sp; Cold Temperature; Coldstress; Dietary Supplements; Docosahexaenoic Acids - biosynthesis; Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific) - antagonists & inhibitors; Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific) - genetics; Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific) - metabolism; Enzyme Inhibitors - pharmacology; Fatty Acid Synthase, Type II - antagonists & inhibitors; Fermentation; Heavy-ions mutagenesis; Ions; Isoniazid; Isoniazid - pharmacology; Mutagenesis; Stramenopiles - drug effects; Stramenopiles - genetics; Stramenopiles - metabolism; Stress, Physiological; Triclosan; Triclosan - pharmacology; Coldstress; Triclosan; Aurantiochytrium sp; Isoniazid; Heavy-ions mutagenesis
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/j.enzmictec.2016.08.019

The important contributions of this original paper lie in •Found the positive effect of inhibitors for enoyl-ACP reductase on DHA production of Aurantiochytrium sp.•Revealed synergistic effect between enoyl-ACP reductase's inhibitors and cold stress on DHA production.•Proposed a strategy for Aurantiochytrium sp. based on heavy-ions mutagensis and synergistic effects. 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.