RESUMEN
Spore-forming Bacillus strains that produce extracellular poly-γ-glutamic acid were screened for their application to natto (fermented soybean food) fermentation. Among the 424 strains, including Bacillus subtilis and B. amyloliquefaciens, which we isolated from rice straw, 59 were capable of fermenting natto. 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 amplified fragment length polymorphism (AFLP) analysis was also conducted on the natto-fermenting strains. The ability to ferment natto was inferred from the two principal components of the AFLP banding pattern, and natto-fermenting strains formed a tight cluster within the B. subtilis subsp. subtilis group.
Asunto(s)
Bacillus subtilis/clasificación , Bacillus subtilis/genética , Oryza/microbiología , Filogenia , Alimentos de Soja/microbiología , Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Bacillus subtilis/aislamiento & purificación , Bacillus subtilis/metabolismo , Biotina/metabolismo , ADN Bacteriano/química , ADN Bacteriano/genética , Fermentación , Datos de Secuencia Molecular , Tipificación de Secuencias Multilocus , Tallos de la Planta/microbiología , Análisis de Secuencia de ADNRESUMEN
The ability to produce exoenzymes of a Bacillus subtilis natto starter strain was improved through selection of a rifampicin-resistant phenotype. Proteomic and zymographic analyses showed increased production of cellulolytic and proteolytic enzymes and decreased production of levansucrase. This mutant had a mutation (S487L) in the ß-subunit of the RNA polymerase.
Asunto(s)
Antibióticos Antituberculosos/farmacología , Bacillus subtilis/enzimología , Celulasas/biosíntesis , Fermentación , Péptido Hidrolasas/biosíntesis , Rifampin/farmacología , Alimentos de Soja , Bacillus subtilis/efectos de los fármacos , Bacillus subtilis/genética , Farmacorresistencia Bacteriana , Espacio Extracelular/enzimología , FenotipoRESUMEN
We investigated the fate of radioactive cesium ((134)Cs plus (137)Cs) during the production of tofu, natto, and nimame (boiled soybean) from a contaminated Japanese soybean cultivar harvested in FY2011. Tofu, natto, and nimame were made from soybean grains containing radioactive cesium (240 to 340 Bq/kg [dry weight]), and the radioactive cesium in the processed soybean foods and in by-product fractions such as okara, broth, and waste water was measured with a germanium semiconductor detector. The processing factor is the ratio of radioactive cesium concentration of a product before and after processing. For tofu, natto, nimame, and for the by-product okara, processing factors were 0.12, 0.40, 0.20, and 0.18, respectively; this suggested that these three soybean foods and okara, used mainly as an animal feed, can be considered safe for human and animal consumption according to the standard limit for radioactive cesium of soybean grains. Furthermore, the ratio of radioactive cesium concentrations in the cotyledon, hypocotyl, and seed coat portions of the soybean grain was found to be approximately 1:1:0.4.