Construction of a thiamine pyrophosphate high-producing strain of Aspergillus oryzae by overexpression of three genes involved in thiamine biosynthesis.

We have found a gene (thiP) encoding thiamine pyrophosphokinase (TPK) in the Aspergillus oryzae genome. No riboswitch-like region was found in the upstream region of thiP, although it was repressed probably by thiamine pyrophosphate (TPP) as well as thiA and nmtA, which are strictly regulated by TPP-riboswitch sequence. To improve the productivity of TPP in A. oryzae, we constructed the strain in which thiA, nmtA and thiP were overexpressed simultaneously. The resulting strain accumulated intracellular TPP 4-fold higher than did the control strain.