Aspergillus oryzae nrtA affects kojic acid production
1a Genome Biotechnology Laboratory , Kanazawa Institute of Technology , Hakusan , Japan.
Bioscience, Biotechnology, and Biochemistry
|April 26, 2016
Summary
The nitrate transporter gene (nrtA) is crucial for Aspergillus oryzae to absorb nitrate for growth. Disrupting nrtA prevented nitrate uptake, impacting kojic acid production.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Nitrate is a key nitrogen source for many microorganisms.
- Understanding nitrate transport mechanisms is vital for microbial physiology and biotechnology.
- Aspergillus oryzae is an important industrial fungus with applications in food and enzyme production.
Purpose of the Study:
- To elucidate the function of the nitrate transporter-encoding gene (nrtA) in Aspergillus oryzae.
- To investigate the role of NrtA in nitrate assimilation and its impact on kojic acid production.
Main Methods:
- Gene disruption of the nrtA gene in Aspergillus oryzae.
- Southern hybridization to confirm homologous recombination.
- Real-time PCR to analyze nrtA gene expression.
- Growth assays with nitrate as the sole nitrogen source.
- Measurement of kojic acid production under different nitrate conditions.
Main Results:
- Gene disruption successfully inactivated the nrtA locus.
- nrtA expression was significantly induced by sodium nitrate (NaNO3).
- The nrtA disruptant showed impaired growth when nitrate was the primary nitrogen source, confirming NrtA's essential role in nitrate uptake.
- Kojic acid production was inhibited by nitrate in the wild-type strain but not in the nrtA-disrupted strain, indicating nitrate's influence on KA production is mediated by NrtA.
Conclusions:
- NrtA is indispensable for efficient nitrate uptake in Aspergillus oryzae.
- The nitrate transporter NrtA plays a regulatory role in kojic acid biosynthesis, likely by controlling nitrate availability.
- These findings provide insights into nitrogen metabolism and secondary metabolite production in A. oryzae.
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