A Novel Protein AoHPS1 Is Involved In Oxidative Stress and Kojic Acid Synthesis in Aspergillus Oryzae

Aspergillus oryzae usually suffers from oxidative stress during the process of aerobic fermentation. However, there is little information on what genes involve in oxidative stress of A. oryzae. Here, we found that the expression of a novel gene Aohps1 was induced during the growth and development of A. oryzae with and without oxidative stress. Sequence analysis revealed that Aohps1 has four transmembrane regions and is conserved in Aspergillus species. Overexpression and deletion of Aohpi1 caused the growth defects with and without oxidative stress, including mycelium growth, conidia formation and biomass. Meanwhile, the Aohpi1 overexpression strain exhibited more sensitivity to oxidative stress than the Aohpi1 disrupted mutant. Furthermore, overexpression and disruption of Aohps1 resulted in the inhibition of kojic acid production with and without oxidative stress, consistent with the reduced expression of kojA that directly contributed to the synthesis of kojic acid. Additionally, the yield of kojic acid is less in the Aohps1 overexpression strain than in the Aohps1 deletion mutant under oxidative stress. Collectively, the discovery of Aohps1 provides new insights into oxidative stress and kojic acid synthesis in A. oryzae.