Novel Leuconostoc starter culture systems for fermentation of kimchi

초록

Leuconostocs and lactobacilli have been known to play important roles in the early and the mid-stage of fermentation of kimchi, but the predominant species remain unknown. To elucidate dominant microorganisms involved in kimchi fermentation and examine their effect on kimchi fermentation, we randomly isolated and characterized 120 lactic acid bacteria from kimchi during a 5-day fermentation at 15 oC. We found that Leuconostoc citreum was dominant during the early and mid-phase of kimchi fermentation and Lactobacillus sake/Lb. curvatus or Lb. brevis were subsequently followed. Eighty-two of 120 isolates (68%) were classified and further identified as Leuconostoc citreum by means of a polyphasic method, including 16S rDNA sequencing and DNA/DNA hybridization. A few Weissella confusa-like strains were also isolated during mid-phase of fermentation. Strain IH22, one of Leuconostoc citreum from kimchi, was used as an additive to evaluate growth and acid production in kimchi fermentation. This strain was consistently maintained as over 95% of whole population in IH22-treated kimchi over a 5-day fermentation, whereas heterogeneous lactic acid bacteria were observed in control kimchi. The pH in IH22-treated kimchi dropped rapidly but was stably maintained for 5 days, compared to its slow and prolonged decrease in control kimchi. These results indicate that Leuconostoc citreum IH22 dominates over and retards the growth of other lactic acid bacteria in kimchi, suggesting strain IH22 can be used as starter culture to maintain the quality of kimchi for prolonged period.