To obtain strains of bacteria suitable for the production of
natto that we have not yet been able to collect in Japan, we explored the Northeastern region of Myanmar. We obtained twenty-nine
Pe pok samples with saline concentrations between 0.14% and 13.7%. We isolated 197 bacteria from the samples and identified 137 strains of
Bacillus subtilis. We selected 42 of these strains as
natto bacilli, as judged from the stickiness of colonies grown on steamed soybeans. The optimal growth temperatures of those 42 strains were as follows : 33°C, 1 strain ; 35°C, 1 ; 37°C, 5 ; 39°C, 9 ; 41°C, 19 ; 43°C, 6 ; 45°C, 1. After manufacturing
itohiki-natto by programming the temperature and moisture throughout the manufacturing process, 10
natto bacilli with high scores in sensory tests were selected. Six strains produced
natto very similar to Japanese
natto, but with a softer texture. The remaining strains produced
natto with a distinctive flavor, taste, or texture from those of typical Japanese
itohiki-natto. These results showed that certain selected
natto bacilli could produce
natto characteristics never before seen in Japan.
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