The characteristics of lactic acid bacteria isolated from Indonesian commercial kefir grain

Abstract

Aims: Kefir is a fermented dairy product using lactic acid bacteria, such as Lactobacillus lactis and L. delbrueckii subsp. bulgaricus mixed with yeast and produces acids and alcohols. Lactic acid bacteria (LAB) can be identified based on morphological and biochemical characteristics, using macroscopic and microscopic examination and biochemical tests. This study aims to isolate LAB from commercial kefir grain and to conduct an identification based on morphological characteristics using macroscopic, microscopic and biochemical techniques. Methodology and results: LAB isolated from kefir grain was grown on nutrient-agar medium and then transferred to the MRS agar medium. Macroscopic observations included recording the colony size, color, form, surface, and edge. Microscopic examination involved Gram staining and spore staining. Biochemical assays included oxidase test and aerobic and anaerobic tests. The results obtained were lactic acid bacteria which were negative in the catalase and oxidase tests, positive for Gram staining, spore staining was negative, and aerobic and anaerobic tests were positive; the bacteria were rod-shaped and rounded. Conclusion, significance and impact of study: Lactic acid bacteria isolated from kefir grains were identified by macroscopic and microscopic examination of morphology and using biochemical tests putatively identified as Lactococcus cremoris, Streptococcus cremoris and L. plantarum.