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

Area of Science:

• Microbiology
• Molecular Biology
• Biotechnology

Background:

• Aspergillus oryzae exhibits light responses, but red light's specific effects on enzyme production remain unclear.
• Inconsistent reports necessitate further investigation into red light's influence on koji fermentation.

Purpose of the Study:

• To elucidate the impact of red light on gene expression for koji enzymes during Aspergillus oryzae fermentation.
• To analyze the specific effects of red light on alpha-amylase, glucoamylase, and protease activity.

Main Methods:

• RNA sequencing of rice koji fermented under red light versus dark conditions.
• Analysis of differentially expressed genes (DEGs) and enzyme activity assays.

Main Results:

• Red light primarily affected genes unrelated to conidiation and saccharification.
• One alpha-amylase gene (homologous to Aspergillus nidulans amyD) was upregulated by red light.
• Red light enhanced alpha-amylase activity in rice koji but did not alter glucoamylase or protease activity.

Conclusions:

• Red light influences Aspergillus oryzae fermentation by modulating specific enzyme gene expression, particularly alpha-amylase.
• The findings suggest red light may regulate alpha-glucan molecular weight via AmyD.
• This research provides insights into light-mediated control of fungal fermentation processes.