Development of Aspergillus oryzae thiA promoter as a tool for molecular biological studies.

In filamentous fungi, the repertoire of promoters available for exogenous gene expression is limited. Here, we report the development and application of the thiamine-regulatable thiA promoter (PthiA) in Aspergillus oryzae as a tool for molecular biological studies. When PthiA was used to express the enhanced green fluorescent protein (EGFP) reporter, the fluorescence in the mycelia was either repressed or induced in the presence or absence of thiamine in the culture media, respectively. In addition, the expression level from the thiA promoter can be controlled by the concentration of external thiamine. Thiamine content in the media did not affect mycelial morphology, making the thiA promoter more useful compared with alcA and amyB promoters that depend on carbon source for regulation. Moreover, as the A. oryzae thiA promoter was also regulated by thiamine in A. nidulans, this promoter can be further applied as an inducible promoter in other Aspergilli.