Isolation, Identification and Preliminary Screening of Acid-Tolerant Lactic Acid Bacteria from Naturally Fermented Pickle Juices from Daqing

Fourteen strains of suspected lactic acid bacteria were isolated from 7 naturally fermented pickle juices gathered from Daqing, Heilongjiang Province. 16S rDNA was extracted from each of these bacterial strains using a bacterial genomic DNA extraction kit. The species were identified by DNA sequencing, homology analysis and phylogenetic tree. The results indicated that the all 14 strains belonged to lactic acid bacteria, including 4 strains of Lactobacillus curvatus(HD12-1, HD13-5, HD14-1 and HD15-1), 1 strain of Lactobacillus brevis(HD18-2), 3 strains of Lactobacillus sakei(HD12-2, HD13-1 and HD16-5), 1 strain of Leuconostoc mesenteroides(HD18-3), and 5 strains of Lactobacillus plantarum(HD14-3, HD15-2, HD16-2, HD17-3 and HD17-4). Among these strains, 6 strains, including HD12-1, HD13-1, HD14-1, HD15-1, HD16-2 and HD16-5, were able to grow at pH 2.5, 3.0 or 3.5, with a survival rate above 2% at pH 3.0.