Abstract
We developed a more convenient method for assaying polyamines and re-examined the variation of polyamine contents during each step of the natto production process. The steaming process slightly decreased spermidine in soybeans, and the subsequent fermentation process resulted in 41.1% increase of spermidine and 19.4% reduction of spermine compared with those of steamed soybeans. These results indicated that Bacillus subtilis (natto) produces spermidine during the fermentation process. Further, we determined that spermidine production differs among inoculum strains. It was also suggested that the selection of starter cultures with high spermidine productivity improves polyamine levels in natto.
