Transcriptome analyses reveal the DHA enhancement mechanism in Schizochytrium limacinum LD11 mutant

Abstract

Schizochytrium is the main strain used for the industrial production of docosahexaenoic acid (DHA), and improving its yield is a constant requirement in the industry. A mutant of Schizochytrium limacinum LD11 with high DHA production was screened through atmospheric and room temperature plasma (ARTP) mutations using S. limacinum B4D1 as parent strain. A comparative transcriptome was used to reveal the DHA production enhancement mechanism of LD11 by comparing with B4D1. The DHA yield of LD11 reached 14.27 g/L, which was 25.51 % higher than that of B4D1. Transcriptome analysis revealed that genes involved in the tricarboxylic acid cycle and citrate transport system were significantly upregulated in LD11 compared with B4D1, providing more acetyl-CoA for the synthesis of fatty acids. Additionally, the triacylglycerol synthesis pathway was upregulated. Genes involved in β-oxidation in mitochondria and peroxisomes were upregulated and downregulated, respectively, resulting in a significant increase in the content of DHA. This study provides an efficient breeding strategy to improve DHA production in Schizochytrium, and it shows that transcriptome results can be used as a basis for metabolic engineering. • Schizochytrium limacinum LD11 with high DHA production was screened. • Comparative transcriptome was conducted to reveal the mutant mechanism. • Genes from TCA, citrate transport system were significantly up-regulated in LD11. Genes involved in β-oxidation in mitochondria were up-regulated in LD11. • Genes involved in peroxisomes were down-regulated in LD11.