Functional myo-inositol catabolic genes of Bacillus subtilis Natto are involved in depletion of pinitol in Natto (fermented soybean).

Abstract

Soybeans are rich in pinitol (PI; 3-O-methyl-D-chiro-inositol), which improves health by treating conditions associated with insulin resistance, such as diabetes mellitus and obesity. Natto is a food made from soybeans fermented by strains of Bacillus subtilis natto. In the chromosome of natto strain OK2, there is a putative promoter region almost identical to the iol promoter for myo-inositol (MI) catabolic genes of B. subtilis 168. In the presence of MI, the putative iol promoter functioned to induce inositol dehydrogenase, the enzyme for the first-step reaction in the MI catabolic pathway. PI also induced inositol dehydrogenase and the promoter was indispensable for the utilization of PI as well as MI, suggesting that PI might be an alternative carbon source metabolized in a way involving the MI catabolic genes. Natto fermentation studies have revealed that the parental natto strain consumed PI while a mutant defective in the iol promoter did not do so at all. These results suggest that inactivating the MI catabolic genes might prevent PI consumption, retaining it in natto for enrichment of possible health-promoting properties.

• Authors: Tetsuro Morinaga, Masanori Yamaguchi, Yuki Makino, Hideaki Nanamiya, Kiwamu Takahashi, Hirofumi Yoshikawa, Fujio Kawamura, Hitoshi Ashida, Ken-Ichi Yoshida
• Journal: Bioscience, biotechnology, and biochemistry (Biosci Biotechnol Biochem) Vol. 70 Issue 8 Pg. 1913-20 (Aug 2006) ISSN: 0916-8451 [Print] England
• PMID: 16880594 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• pinitol
• Inositol
• L-Iditol 2-Dehydrogenase

Topics

• Bacillus subtilis (genetics, growth & development, metabolism)
• Base Sequence
• Fermentation
• Genes, Bacterial
• Inositol (analogs & derivatives, chemistry, metabolism)
• L-Iditol 2-Dehydrogenase (chemistry, metabolism)
• Molecular Sequence Data
• Soy Foods (microbiology)
• Soybeans (chemistry, microbiology)