Alkane Utilization, the Expression and Function of Cytochrome P450in Sophorolipid Synthesis in Starmerella bombicola CGMCC 1576

Several alkanes were respectively added to four fermentation media to investigate the effects of alkanes on sophorolipids (SLs) production and expression levels of cytochrome P450 (P450) genes in Starmerella bombicola CGMCC 1576. The production of total SLs produced from n-tetradecane, n-hexadecane and n-octadecane was respectively 14.07 g l-1, 31.73 g l-1 and 27.2 g l-1. More lactonic SLs were produced from n-tetradecane and n-hexadecane while more acidic SLs were produced from n-octadecane. Furthermore, six P450 genes were found from S. bombicola by genome sequencing. CYP52-M1 gene was inducibly expressed by all used n-alkanes except that n-decane was not expressed without glucose. CYP52-E1 gene was inducibly expressed by some specific alkanes in various C/N ratios. In the media without glucose, CYP52-E2 gene was inducibly expressed by all used n-alkanes except n-octane and CYP52-N1 gene was inducibly expressed by n-octadecane. CYP52-N2 and CYP-X genes did not play the same important roles on alkane utilization as other P450 genes. Varying degrees of alkane utilization can guide the purposeful production of total, lactonic or acidic SLs, and the six P450 genes were expressed at different levels by alkanes and played different roles on alkane utilization.