Xi Cao,Yayu Pan,Wei Wei,Tinglan Yuan,Sen Wang,Lingyun Xiang,Yongjun Yuan
Effects of various fermentation conditions on fatty acid composition of single cell oil (SCO) from Trichosporon sp. F1-2 were investigated. Ten carbon sources clustered into two groups using hierarchical clustering algorithm and principal component analysis. Xylose and soluble starch from each group were further studied. SCO using xylose had a high oleic acid content, while the linoleic acid and α-linolenic acid content increased significantly in SCO using soluble starch especially at the sn -2 position. 20 and 31 triacylglycerol (TAG) types were detected, respectively. The increased types were rich in linoleic acid and α-linolenic acid. The effect of C/N ratios was the weakest (distance threshold 3.05), followed by inoculation amounts (3.08), fermentation time (4.30) and nitrogen sources (5.64). The optimum nitrogen source, C/N ratio, inoculation amount and fermentation time for SCO accumulation were ammonium sulfate, 60, 6% and 120 h, respectively. Two different SCOs were produced using xylose and soluble starch under optimum conditions, which were demonstrated to be potential substrates for synthesis of 1,3-distearoyl-2-oleoyl-glycerol (a cocoa butter improver) and MLM-type TAG (the dietary TAG with low caloric value) respectively. Therefore, changing the carbon source can help broaden application fields of SCOs and increase feedstock sources of structured TAG synthesis.
Lipase catalysis has become the most promising technique for enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) due to its mild and green conditions. In this study, Trichosporon sp. F1-2 was newly isolated from oil-contaminated sludge, and its extracellular lipase was purified using ammonium sulfate precipitation and DEAE-Sepharose chromatography. The molecular weight of the lipase was estimated to be 32.6 kDa. The optimal temperature and pH for lipase activity were 50 °C and 8.0, respectively, and the optimal storage conditions were found to be temperatures below 45 °C and pH 7.0–9.0. The lipase did not require metal ions as cofactors and was significantly inhibited by Zn 2+ . It was stable in various organic solvents with different log P values, and n-hexane, toluene, dichloromethane, diethyl ether and glycerol even enhanced its activity. It had sn -1,3 regioselectivity and the highest activity towards a medium-chain fatty acid (C8) ester. This study demonstrated the lipase has good potential as a catalyst in enrichment of EPA and DHA in fish oil. The content of EPA and DHA reached 22.9 and 25.4 mol%, respectively, using 100 U of the lipase within 24 h, and the enrichment efficiency of DHA was higher than that of EPA.
危险品化学品经营许可证（带存储）