Heterologous expression of AoD9D enhances salt tolerance with increased accumulation of unsaturated fatty acid in transgenic Saccharomyces cerevisiae
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Salt stress can trigger several physiological responses in microorganisms such as the increasing accumulation of unsaturated fatty acid, which was biosynthesized by delta-9 fatty acid desaturases (D9D) at the first step. In the present study, two D9D genes, designated AoD9D1 and AoD9D2, were isolated from Aspergillus oryzae. The expression analysis showed that AoD9D1 and AoD9D2 were upregulated under salt stress. To investigate the function of AoD9D, transgenic Saccharomyces cerevisiae strains that heterologously expressed AoD9D were exposed to salinity condition. These transgenic strains exhibited greater tolerance to salt stress than wild-type strains, and the heterologous expression of AoD9D increased the content in unsaturated fatty acids as compared to control cells. Moreover, AoD9D1 and AoD9D2 both contained fatty acid desaturase (FAD) and cytochrome b5-like Heme/Steroid-binding domains (Cyt-b5). S. cerevisiae separately transformed with the gene fragments coding for the FAD and Cyt-b5 domains in the AoD9D1 protein grew better and accumulated a higher concentration of unsaturated FAs than the control. Altogether, the heterologous expression of AoD9D enhanced the tolerance of transgenic S. cerevisiae to high salinity stress with increased accumulation of unsaturated fatty acid. The results provide some practical basis for the successful development of salt-tolerant fermentation microorganisms.
KeywordsAspergillus oryzae Fatty acid desaturases Salt stress Unsaturated fatty acid
This work was supported by the National Natural Science Foundation of China (NSFC) (Grant no. 31460447 and 31700068), International S&T Cooperation Project of Jiangxi Provincial (Grant no. 20142BDH80003), Doctor and master specific projects of Honghe University (XJ17B09), Science and Technology Research Project of Jiangxi Provincial Department of Education (GJJ180605), the Science Funds of Natural Science Foundation of Jiangxi Province (20114BAB205039, 20171BAB214004).
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Conflict of interest
We declare that we have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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