Isolation, screening and identification of lactic acid bacteria from the traditional fermented soybean paste

Lactic acid bacteria play a leading role in the natural fermentation progress of soybean paste, they have heavy correlations to the flavor and the quality of the soybean paste. Lactic acid bacteria could produce small molecule aldehydes, acids, esters and so on by fermenting carbohydrate to the flavor of the soybean paste. In this study, we used the fermented soybean paste from Heilongjiang Province as material, analyzed lactic acid bacteria during the fermentation using the methods of traditional isolation, culture, screening, identification and 16S rDNA gene sequences technology. Through calcium-dissolving zone, we isolated 44 strains lactic acid bacteria from the samples. There are 6 strains named as: HDBL-1, HDBL-2, HDBL-3, HDBL-4, HDBL-5, HDBL-6, which were negative in hydrogen peroxide test, while were positive in Gram stain. Then the salt-tolerant with low lactic acid activity HDBL-7 was isolated and identified to be Pediococcus acidilactici. The research laid the foundation for the quality study and industrial production of soybean paste.