Bacillus subtilis (natto) Bacteriophages Isolated in Japan

Abstract

Natto, a fermented soybean food made in Japan, is spoiled occasionally by Bacillus subtilis (natto) bacteriophages. Twenty phages, primarily isolated from abnormally fermented natto, were classified into two groups based on host ranges and comparative whole-genome hybridization. JNDMP (group I) had a hexagonal head (diameter, 60 nm), a flexible tail (length, 200 nm) and required a magnesium ion for amplification. ONPA (group II) had a hexagonal head (diameter, 89 nm) and a sheathed tail (length, 200 nm). Genome sizes of JNDMP and ONPA were estimated to be 42 kb and 91 kb, respectively. Previously reported phages from three serologically different groups of B. subtilis (natto) were also classified into group I or group II based on the results of Southern hybridization using JNDMP and ONPA genomic DNA as probes. These results suggest that there are at least two groups of B. subtilis (natto) phages in Japan.