In commercially obtained
natto and experimentally-prepared
natto preparations, relatively high concentrations of dipicolic acid, 20.55±13.67 mg/100g
natto (0.006-0.048%, wet weight) were detected, using a simple method combined with ion-exchange column and colorimetric assay procedures. These values were less than that of the previous data (0.06-0.20%, wet weight) reported 60 years ago. Dipicolic acid was thought to be an intracellular component of
natto bacilli and could be extracted in the water-soluble fraction by heat-treatment of the sample for 30min at 120°C. Furthermore, the partially purified material from
natto bacilli caused very strong inhibition of the growth of
sake yeasts (Kyokai 7 and Kyokai 9 mutant).
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