Efficient synthesis of medium-chain ω-hydroxy fatty acids by metabolic engineering in Candida tropicalis

Abstract:

[Objective] ω-hydroxy fatty acid (ω-HFAs) is a green, safe, non-toxic, ideal biodegradable material with good biocompatibility. It is widely used in chemical industry, food, pharmacy. Microbial fermentation, the method for producing ω-HFAs has important research significance and application prospects.[Methods] In order to obtain high-yield metabolically engineered strains of ω-hydroxy fatty acids, the POX gene in the β-oxidation of Candida tropicalis was continuously knocked out through homologous recombination technology. The effect of gene deletion on cell growth and the ability to synthesize ω-hydroxy fatty acids was investigated.[Results] The recombinant strain F4PT (ΔPOX4, ΔPOX5) was successfully constructed. Growth in the medium with fatty acid methyl esters (C₁₂~C₁₄) as the carbon source was significantly slower than that in glucose, indicating that the deletion of the POX4 and POX5 genes reduced the metabolic ability of fatty acid methyl esters. Secondly, through the fermentation experiment, the concentration of 12-hydroxydodecanoic acid and 14-hydroxytetradecanoic acid were 3.01 g/L and 8.69 g/L, the conversion rates were 11.44% and 33.14%, respectively. The ability to metabolize fourteen-carbon fatty acids is significantly stronger than that of twelve-carbon fatty acids.[Conclusion] Candida tropicalis with double deletion of FAO and POX genes can obviously accumulate ω-hydroxy fatty acids, but the accumulation efficiency of different carbon chains is different. The production and conversion rate of 14-hydroxytetradecanoic acid are higher, and the recombinant strain has the potential to convert methyl tetradecanoate to 14-hydroxytetradecanoic acid.