Isolation and characterization of lactic acid bacteria from Yan-tsai-shin (fermented broccoli stems), a traditional fermented food in Taiwan

Abstract

To isolate, characterize and identify lactic acid bacteria (LAB) in yan-tsai-shin (fermented broccoli stems), a traditional fermented food in Taiwan. A total of 226 LAB were isolated; 111 cultures were isolated from samples collected from seven different markets and 115 from six fresh broccoli samples. These isolates were characterized phenotypically and then initially divided into nine groups (r1 to r9) using restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Some isolates were further divided into four additional groups by other genetic analysis. The most common bacterial genera in yan-tsai-shin and fresh broccoli were Weissella, Lactococcus and Lactobacillus. Regional similarities in the LAB, with differences in diversity, were observed in this study. On the basis of phylogenetic analysis of 16S rRNA, rpoA, rpoB and pheS gene sequences, two strains were included in the genera Enterococcus and Lactococcus, respectively, and identified as potential novel species or subspecies. In addition, the novel enterococcal strain, and 33 L.lactis subsp. lactis and two Weissella cibaria strains were found to have bacteriocin-like inhibitory substance (BLIS) producing abilities. These results suggest that the LAB play important roles in the fermentation of yan-tsai-shin. This is the first report describing the distribution and varieties of LAB existing in yan-tsai-shin and fresh broccoli. In addition, two potential novel LAB species or subspecies and one potential novel BLIS were also found in this study.