title: 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.affiliation: Department of Biofunctional Chemistry, Faculty of Agriculture, Kobe University, Hyogo, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Morinaga
authors.forename: Masanori
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Makino
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nanamiya
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Takahashi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Fujio
authors.initials: F
authors.lastname: Kawamura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ashida
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D001483:Base Sequence; D005285:Fermentation; D005798:Genes, Bacterial; D007294:Inositol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D007064:L-Iditol 2-Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D045730:Soy Foods / Q000382:microbiology*; D013025:Glycine max / Q000737:chemistry / Q000382:microbiology
chemical_list: C021730:pinitol; D007294:Inositol; D007064:L-Iditol 2-Dehydrogenase