A lignocellulosic hydrolysate-tolerant Aurantiochytrium sp. mutant strain for docosahexaenoic acid production. (March 2017) - Qi, Feng
Highlights: A novel hydrolyzate-tolerant Aurantiochytrium sp. FN21 mutant strain was obtained. Aurantiochytrium sp. FN21 can accumulate lipid and DHA using hydrolyzate medium. Higher DHA production is achieved by the mutant than its parental strain. The key genes and cellular pathways associated with tolerance are illustrated. Abstract: To utilize lignocellulosic hydrolysate for docosahexaenoic acid (DHA) production, a novel mutant Aurantiochytrium sp. FN21 with strong tolerance against inhibitory lignocellulosic hydrolysate was obtained through continuous domestication processes from the parent strain Aurantiochytrium sp. FJU-512. Aurantiochytrium sp. FN21 can accumulate 21.3% and 30.7% more DHA compared to its parent strain cultured in fermentation medium and a medium with 50% (v/v) sugarcane bagasse hydrolysate (SBH), respectively. After optimization with different nitrogen sources, the highest lipid (11.84 g/L) and DHA (3.15 g/L) production were achieved in SBH. The results demonstrated that Aurantiochytrium sp. FN21 has the commercial applications for DHA production using lignocellulosic hydrolysate. In order to elucidate the tolerance mechanism, transcriptomic profiling of the two strains was studied. The highly up-regulated genes and corresponding cellular pathways (TCA cycle, amino acid biosynthesis, fatty acid metabolism and degradation of aromatic compounds) are considered to be associated with the hydrolysate-tolerance of Aurantiochytrium sp. FN21.