3. Results and discussion
3.1. Isolation and identification of probiotic strains from kimchi
Twenty-five Lactobacillus strains were isolated from various home-made kimchi samples. Among these, only 2 strains were found to be resistant to artificial gastric juice (pH 2.5, 1% pepsin) and artificial bile acid (0.3% oxgall). The SY11 and SY12 strains showed high survival rates of 98.5% and 99.0% in artificial gastric juice, and 93.7% and 97.9% in artificial bile acid, respectively. L. plantarum isolated from raw fruits and vegetables showed a high survival rate of 82% ( Vitali et al., 2012). Therefore, these strains are worthy of consideration for commercial use in a base of a high survival rate. The tolerance of lactobacilli to acid was originated from presence of a constant gradient between extracellular and cytoplasmic pH by F0F1-ATPase ( Corcoran, Santon, Fitzgerald, & Ross, 2005). In addition, the tolerance to bile salt was originated from excretion of bile salt hydrolase ( Guo et al., 2009). These bile salt hydrolase of LAB can be provided of potential to lower serum cholesterol level.
SY11 and SY12 strains were identified as L. plantarum, with 99.9% similarity via gram staining, carbohydrate utilization, and 16S rRNA sequencing (data not shown). Therefore, these 2 strains were named L. plantarum SY11 and L. plantarum SY12, respectively.