LACTIC ACID BACTERIA AND YEASTS FROM INDONESIAN KEFIR GRAINS AND THEIR GROWTH INTERACTIONDANDY YUSUF, LILIS NURAIDA, RATIH DEWANTI-HARIYADI AND DASE HUNAEFI
Kefir grain, a starter culture for kefir fermentation, is polysaccharides and protein matrixes consisting of various lactic acid bacteria and yeasts. The aim of this study was to (1) enumerate, isolate and identify predominant LAB and yeast from Indonesian kefir grains and (2) evaluate the growth of LAB and yeast isolates in skim milk. The results revealed that the LAB counts reached 9 log CFU/g, while the yeast counts reached 8 log CFU/g. Presumptive Lactobacillus reached 8 log CFU/g, which was higher than Lactococcus and Leuconostoc. Identification by API test kits revealed that the predominant species of LAB were Lactobacillus fermentum 1, Lactobacillus brevis 3, Lactobacillus paracasei ssp. paracasei, and Lactococcus lactis ssp. lactis. The predominant yeasts were Saccharomyces cerevisiae, Candida krusei/inconspicua, Candida parasilopsis, Candida glabrata, and Kloeckera spp. The ability of LAB and yeast isolates to acidify and coagulate milk varied. Co-culture of Lactobacillus rhamnosus YK12 and Saccharomyces cerevisiae YKPD6 showed that both were growing well in skim milk, suggested that both isolates could be used to develop a defined starter culture for kefir fermentation.