| Description |
Aurantiochytrium sp. is a genus of unicellular heterotrophic marine protist, which is consider to be a promising DHA-producing microorganism. In order to improve the DHA production, atmospheric and room temperature plasma (ARTP) technology was applied to the mutagenic breeding of Aurantiochytrium sp. R2, and multi-omics were adopted to analyze the biosynthesis mechanism. The optimal ARTP mutagenic treatment time was 60 s, and the screening concentration of malonic acid was 0.4 g/L. According to the growth and DHA accumulation profiles, the mutant strain Aurantiochytrium sp. R2A35 was selected from 59 mutants with the highest DHA yield. The DHA yield of the mutant strain Aurantiochytrium sp. R2A35 was 8.70 g/L, which were increased by 32.47% compared to the wild strain. Moreover, the DHA content in biomass as 39.72% was the highest DHA productivity reported so far. Then combined transcriptome and proteome techniques were adopted to analyze the differentially expressed genes and the differential proteins, revealing the biosynthesis mechanism for the improve of DHA production. Multi-omics indicated that the expression of acetyl-CoA carboxylase was up-regulated in Aurantiochytrium sp. R2A35, and the fatty acid synthase (FAS) pathway was concurrently down-regulated, so that more precursor was transported to the polyketide synthase (PKS) pathway. Thus, the DHA content in total lipids was greatly improved from 49.39% of the wild strain R2 to 63.69% of the mutant strain R2A35, thereby increasing the DHA yield from 6.57 to 8.70 g/L. This research would provide reference for breeding engineering of DHA producing microorganisms and understanding the DHA metabolism process. |
