Comparison of Acid Phosphatase Gene Expression Profiles in Solid-State Rice and Soybean Cultures of an Aspergillus oryzae Strain with Low Acid Phosphatase Activity (KBN8048): Implications for Miso Brewing

抄録

Aspergillus oryzae KBN8048 was selected as a strain exhibiting low level acid phosphatase activity in solid-state rice and soybean cultures for miso brewing. The activity was particularly low in the latter case, and was correlated with decreased dephosphorylation activity of IMP, an enhancer of miso palatability. Based on transcriptional properties, 13 acid phosphatase genes in the fungus were classified into type R and type S, which exhibited higher expression in solid-state rice and soybean cultures, respectively. Type R genes appeared to be up-regulated in response to acidic pH and limited phosphate availability in the culture via a pH-dependent transcriptional factor, PacC, and a functional counterpart of Saccharomyces cerevisiae Pho4p, which transcriptionally activates phosphatase genes under phosphate-limited conditions, respectively. On the other hand, existence of type S genes suggested an unknown mechanism that responds to inductive regulatory cue(s) other than pH and phosphate availability in solid-state soybean culture.