Isolation, Identification, and Characterization of Bacillus strains from the Traditional Korean Soybean-fermented Food, Chungkookjang

A total of 45 bacterial strains were isolated from the traditional Korean soybean-fermented food, Chungkookjang. Among these strains, seven strains were selected and identified based on morphological, physiological, and biochemical characteristics, as well as phylogenetic analysis using 16S rDNA sequences. All strains were Gram-positive, aerobic, motile, oxidase-positive, rod-shaped, and endospore-forming bacteria, and produced extracellular enzymes such as amylase, cellulase, lipase, protease, and xylanase. The isolates were grown in the presence of 0-11% (w/v) NaCl. Growth was optimal at pH 6-9 and at temperatures of . According to VITEK automicrobic system tests and supplementary tests, the isolates were similar to several species of the genus Bacillus. The phylogenetic analysis of seven bacterial strains based on comparisons of 16S rDNA sequences, revealed that the strains were closely related to Bacillus species. The identification of strains that produced surfactin was also carried out, based on PCR screening of the sfp gene. Among the seven isolated strains, six yielded a surfactin-positive result with PCR.