Transcriptome analysis of red-light effect on Aspergillus oryzae during rice koji fermentation

Aspergillus oryzae can respond to light, but reports of the effects of red light on it are inconsistent. Here we sequenced RNA of rice koji during fermentation under red light and in the dark to elucidate the influence of red light on the expression of genes for koji enzymes. The set of differentially expressed genes (DEGs) largely excluded genes involved in conidiation and saccharification. Red light upregulated only one α-amylase gene, which is homologous to amyD of Aspergillus nidulans. As AmyD regulates the molecular weight of α-glucan, red light might regulate α-glucan molecular weight. Red light enhanced α-amylase activity of rice koji in fermentation by A. oryzae, had no effect on glucoamylase and protease activity.