Mutagenesis of Arachidonic Acid-producing Mortierella Isabellina and Analyses of △6-desaturase Role by qPCR

Arachidonic acid (AA or ARA), an essential ω?6 polyunsaturated fatty acid (PUFA), can be produced by Mortierella isabellina. Mutagenesis on Mortierella isabellina As3.3410 was induced to raise ARA production. The mutant strain of YZ-124 had the highest ARA of 4.72 g ? L^?1, which was 5.5 times higher than that of the original strain 3.3410. mRNA expression level of Δ6-desaturase was determined in five different kinds of ARA-producing Mortierella isabellina after cultured for 7 days, and in the mutant strain YZ-124 over a 3–8 day time-course. In addition, the desaturase activity and ARA content were measured at the selected time points. The lowest expression of Δ⁶-desaturase was observed in the original strain and the highest expression in the mutant strain YZ-124, which increased with increasing time in culture. Furthermore, a positive correlation was observed between the expression levels of Δ⁶-desaturase and ARA content. Based on this, Δ⁶-desaturase played a significant role in ARA synthesis pathway in Mortierella isabellina.