Enhancing tricarboxylate transportation-related NADPH generation to improve biodiesel production by Aurantiochytrium

Aurantiochytrium, a unicellular eukaryotic marine microalga, is receiving considerable research attention because of its great potential in lipid and biodiesel production. To enhance the saturated fatty acid (SFA) and biodiesel production in Aurantiochytrium, we first aimed to improve tricarboxylate transportation-related NADPH generation by overexpressing the malic enzyme (ME)-encoding gene. The SFA yield of the resultant recombinant strain, termed SD116::ME, reached 6.42 g L−1. Subsequently, by feeding 30 mM malic acid at the late logarithmic phase, the SFA yield was further increased to 8.65 g L−1, which was an increase of >105% compared to the yield in the wild type. Moreover, the enhanced activities of ME and malic acid dehydrogenase led to an improvement in tricarboxylate transportation-related NADPH generation, which is essential for biodiesel production. This is the first report indicating a possibility for large-scale biodiesel production by regulating the NADPH generation system in Aurantiochytrium. [Display omitted] •Aurantiochytrium could be developed as a candidate for biodiesel production.•Saturated fatty acid yield reached 8.65 g L−1 in Aurantiochytrium sp. SD116::ME.•Malic enzyme gene was successfully overexpressed in Aurantiochytrium sp. SD116::ME.•Biodiesel production was improved by enhancing the tricarboxylate transportation.