Identification and characterization of lactic acid bacteria isolated from traditional pickles in Sichuan, China

The pickle, a traditional fermented vegetable product, is popular in Sichuan Province of China. The objective of this study was to investigate the diversity of dominant lactic acid bacteria (LAB) in pickles by analyzing 36 samples collected from 6 different regions in Sichuan Province. The LAB counts in these samples varied from 3.90 to 8.40 log cfu ml(-1). In total, 185 presumptive LAB with Gram-positive and catalase-negative properties were obtained from these samples using MRS agar, and those strains were identified at the species level by physiological tests, 16S rRNA gene sequencing and multiplex PCR assay. The results revealed that all isolates were accurately identified as Enterococcus thailandicus (2 strains), Lactobacillus alimentarius (16 strains), L. brevis (24 strains), L. paracasei (9 strains), L. plantarum (81 strains), L. pentosus (38 strains), L. sakei (8 strains), L. spicheri (1 strain), Leuconostoc lactis (1 strain) and Pediococcus ethanolidurans (5 strains). The predominant LAB in Sichuan pickle was L. plantarum, which were isolated from most samples. The results also demonstrated that different regions in Sichuan Province have complex compositions of LAB species, and such a rich resource of LAB strains provides raw data for further studies involving probiotic strain selection.