Isolation and characterization of Bacillus subtilis from commercially available honey and its application in natto fermentation

Abstract

Natto is a fermented food made from soybeans using Bacillus subtilis natto. B. subtilis is present in honey. In this study, we evaluated the genetic and enzymatic characteristics of B. subtilis obtained from commercial honey and its suitability for natto fermentation. Three bacterial strains isolated from honey samples of different origins were found to be highly homologous to B. subtilis via 16S rDNA analysis. Similar to B. subtilis natto, all three isolates were biotin auxotrophs and possessed two insertion sequences. Genotyping by random amplified polymorphic DNA-polymerase chain reaction and enzyme activity analysis showed that the isolates were genetically different from the commonly used natto strains Miyagino, Takahashi, and Naruse. The three isolates are highly suitable for natto fermentation. These results indicate that honey is a source of B. subtilis natto that is potentially useful in the food industry.