Effects of SclR on metabolite production in Aspergillus oryzae

Abstract

Aspergillus oryzae, an industrially important fungus utilized for the traditional fermentative manufacturing, produces diverse metabolites and enzymes during fermentation. In our previous study, we have ever identified and characterized a basic helix-loop-helix (bHLH) transcription factor, SclR, and found that the transcription factor is importantly involved in the conidiation, sclerotial formation, and hyphal morphology in A. oryzae. In this study, we further analyzed the effect of SclR on metabolites production in A. oryzae. The control strain and ∆sclR strain were cultivated in dextrin-polypeptone-yeast extract (DPY) liquid medium at 30 °C for 3 days and metabolites were extracted from strains. Liquid chromatography-mass spectrometry (LC-MS) analysis result showed that a total of 1,855 precursor molecules were obtained in the positive ion mode and 2,475 precursor molecules were obtained in the negative ion mode. Comparative analysis of the metabolome indicated that 259 were differentially expressed metabolites. Among of them, 161 metabolites were increased by 1.5-fold, and 98 metabolites were decreased by 1.5-fold in an sclR gene deletion strain compared to the control. Further identification of differentially expressed metabolites revealed that the production level of some organic acids, amino acids, and sugar alcohols were markedly changed in ∆sclR strain relative to control strain. Especially, some organic acids were identified to be intermediates in the citric acid cycle, which is a key metabolic pathway that connects carbohydrate, fat, and protein metabolism. The result also implied that the SclR is potentially involved in energy metabolism.