MANAGEMENT AND GENETIC CHARACTERIZATION OF AGRICULTURAL AND BIOTECHNOLOGICAL MICROBIAL RESOURCES
Location: Bacterial Foodborne Pathogens & Mycology Research Unit
Title: Phylogenetic analysis of Bacillus subtilis strains applicable to natto (fermented soybean) production
| Kubo, Yuji - |
| Takakoshi, Yoshiki - |
| Nakagawa, Rikio - |
| Hasegawa, Hiromasa - |
| Kimura, Keitarou - |
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 2011
Publication Date: September 12, 2011
Citation: Kubo, Y., Rooney, A.P., Takakoshi, Y., Nakagawa, R., Hasegawa, H., Kimura, K. 2011. Phylogenetic analysis of Bacillus subtilis strains applicable to natto (fermented soybean) production. Applied and Environmental Microbiology. 77:6463-6469.
Interpretive Summary: Bacillus subtilis and Bacillus amyloliquefaciens are two species of bacteria that are used to ferment various types of food products, including many different soy-based foods such as natto. Foods fermented from soybean represent a growing market for American soybean producers, so it is important to discover and characterize novel microbial germplasm that can improve industrial processing of these products. In this paper, we characterize several novel natto-fermenting strains and describe a genetic method to rapidly identify superior natto-fermenting strains.
Spore-forming Bacillus strains that produce extracellular poly-'-glutamic acid were screened for their application to natto (fermented soybean food) fermentation. Among the 365 strains, including B. subtilis and B. amyloliquefaciens, which we isolated from rice straw, 59 were capable of fermenting natto. Among these, we found that biotin auxotrophism was tightly linked to natto fermentation. A multilocus nucleotide sequence of six genes (rpoB, purH, gyrA, groEL, polC, and 16S rRNA) was used for phylogenetic analysis, and FAFLP analysis was also conducted on the natto-fermenting strains. We show that the latter can be used to infer natto fermentation capability based on an analysis of the FAFLP banding pattern alone. With respect to phylogenetic relationships, most of the strains formed a tight cluster within the B. subtilis subsp. subtilis group. However, a novel group of natto-fermenting strains closely affiliated with B. amyloliquefaciens were also identified.