A novel NADH fluorescence-based method for identifying and monitoring lactic acid bacteria growths in kimchi

NADH-based fluorescence method was developed to enumerate and differentiate lactic acid bacteria (LAB). The growths of LAB were determined at ?1.5–30 ℃ in MRS medium and kimchi juice. LAB growths were measured by viable cell counting and measuring culture turbidity (A₆₀₀) and NADH fluorescence at 460 nm (F₄₆₀). Each LAB strain had a unique F₄₆₀ value at different growth temperatures. Based on the F₄₆₀ values of LAB strains cultivated at different temperatures, LAB were identified and counted at the species and genus levels in MRS medium and kimchi juice. The fluorescence method was also used to measure changes in LAB dynamics during kimchi fermentation. Obvious increases in F₄₆₀ values were observed for kimchi samples with LAB counts of > 8 log CFU mL^?1, except for Weissella koreensis. Our results indicate that the devised NADH fluorescence method can be used to determine the progress of kimchi fermentation and LAB growths during kimchi storage.