Response mechanism of the docosahexaenoic acid producer Aurantiochytrium under cold stress

Abstract

Aurantiochytrium is a commercial docosahexaenoic acid (DHA) producer, and its DHA content can be significantly increased under cold stress. Given this response to low temperature, we examined proteomics changes in Aurantiochytrium under cold stress. We detected approximately 700 protein spots using two-dimensional gels, whereas using iTRAQ technology, we detected 4650 types of proteins and successfully identified >53%. The results indicated that cold stress inhibits the cellular energy supply from glycolysis and the TCA cycle, to ensure a sufficient supply of NADPH and ribose for anabolism. In contrast, the pentose phosphate pathway was not affected. With respect to lipid synthesis, low temperature led to a significant down-regulation and up-regulation of fatty acid synthase and polyunsaturated fatty acid synthase, respectively, and restricted the protein synthesis of diacylglycerol O-acyltransferase and phospholipid: diacylglycerol acyltransferase. These results show the preferential biosynthesis of polyunsaturated fatty acids and phospholipids by Aurantiochytrium, which collectively serve to increase cell survival rates in cold environments.