Mutagenesis of Arachidonic Acid-producing Mortierella Isabellina and Analyses of Δ6-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.