PCR-DGGE analysis of population dynamics of lactic acid bacteria in kimchi by addition of bacteriocins.

The effects of two crude bacteriocins (DF01 and K10) on lactic acid bacteria (LAB) communities and pH during kimchi fermentation were analyzed by polymerase chain reactiondenaturing gradient gel electrophoresis (PCR-DGGE). Crude LAB bacteriocins, prepared by ammonium sulfate precipitation, were added at 5 AU/mL, and kimchi was incubated at 20°C for 7 days. The pH and titratable acidity of the kimchies were determined daily, and the amplified 16S rRNA products were analyzed by PCR-DGGE. The common and main LAB were Weissella spp., Leuconostoc spp., and Lactobacillus spp. from both control and bacteriocin-treated samples. Among them, W. koreensis, W. confusa, and Lb. sakei were the predominant microorganisms throughout the fermentation period. Some obligate and facultatively heterofermentative LAB were detected from the bacteriocin-treated samples. The pH of the kimchi samples treated with each bacteriocin was higher (ca. 0.8 unit) than that of the control at day 4 and 5.