PNNL

Abstract

Fatty acids are attractive molecules as source materials for the production of biodiesel fuel. Previously, we attained a 2.4-fold increase in fatty acid production by increasing the expression of fatty acid synthesis-related genes in Aspergillus oryzae. In this study, we achieved an additional increase in the production of fatty acids by disrupting a predicted acyl-CoA synthetase gene in A. oryzae. The A. oryzae genome is predicted to encode six acyl-CoA synthetase genes and disruption of AO090011000642, one of the six genes, resulted in a 9.2-fold higher (corresponding to an increased production of 0.3 g/L) accumulation of intracellular fatty acid than that in the wild-type strain. Furthermore, by introducing a niaD marker gene of A. nidulans to the disruptant, as well as changing the concentration and source of nitrogen in the culture medium from 10 mM sodium glutamate to 350 mM sodium nitrate, the yield of fatty acids reached 1.8 g/L. Analysis of the relative composition of the major intracellular fatty acids caused by the disruption of AO090011000642, in comparison with the composition of the wild-type strain, showed an increase of stearic acid (7% to 26%), decrease of linoleic acid (50% to 27%), and no significant change of palmitic acid and oleic acid (each around 20-25%).