Abstract
In this study, we examined the bacteria of fermented food produced in North Vietnam. The samples produced in Hanoi city were collected in March 2003. Salt concentrations, pH and microflora of 5 kinds of 37 samples were analyzed. The salt concentrations tend to be lower than that of Japanese lightly fermented vegetables and some samples did not ferment enough to increase the acidity. The aerobic plate count varied between 5 to 8 log CFU/g. Two to five log CFU/g of coliform bacteria were also detected; all identified strains were similar to as known natural flora in fresh vegetables however. Lactic acid bacteria (LAB), including Lactobacillus spp., Leuconostoc spp., Lactococcus spp. and Pediococcus spp., were isolated from samples. Bacteriocin producing strains effective for Listeria monocytogenes were screened from the isolated 200 LABs. Three Lactococcus lactis spp. lactis strains producing nisin were obtained. The DNA sequences of nisA gene (structural gene of nisin A) were completely the same as that of previously reported ones. A Bacilus subtilis strain that exhibited antimicrobial activity against Gram-positive bacteria was also isolated from a lightly fermented eggplant.
