Abstract
Exopolysaccharides (EPSs) have been widely used in the food industry as viscofying, stabilizing, and emulsifying agents as well as in the pharmaceutical industry for their immunomodulatory, anti-tumor, and anti-inflammatory effects. A total of 458 lactic acid bacteria (LAB) strains isolated from several kinds of soybean pastes were screened for the production of homo-EPS (HoPS). LAB isolates were primarily screened using thin layer chromatography (TLC) and further screened polymerase chain reaction (PCR) targeting genes involved in HoPS production. Six LAB isolates producing high amounts of HoPS were identified by TLC. Among these isolates, glucansucrase gene was amplified in two strains (JSA57, JSB22), whereas the fructansucrase gene was detected in three strains (JSA57, JSB22, JSB66). After isolating the strains, their morphological characteristics and 16S rDNA sequences were determined. Six species were identified as L. alimentarius HSB15, L. plantarum JSA22, L. pentosus JSA57, L. brevis JSB22, L. alimentarius JSB66, and L. parabrevis JSB89. To evaluate the potential probiotic properties of these LAB, their survival rates against a simulated intestinal environment were determined. After 2 hr of incubation in artificial gastric juice, survival rates of JSA57, JSB90, JSB22, and JSB66 were all greater than 50%. After 2 hr of incubation in bile juice, viable cell count of JSB22 was similar with initial vial cell counts. Growth of the six LAB was screened in arabino-oligosaccharide (AOS)-containing MRS broth. Results showed that growth of the isolates selectively increased after culture in AOS-containing media. Strain JSB22 (6 hr), JSB66 (6 hr), HSB15 (20 hr), and JSA22 (29 hr) showed maximum growth rate. Especially, JSB22 showed the highest growth rate. These results suggest that EPS-producing LAB isolated from Deonjang could be applied as synbiotics.
전통 장류에서 유산균 성상을 보이는 균주를 분리하여, TLC와 PCR을 통하여 HoPS를 우수하게 생성하는 균주 HSB15, JSA22, JSA57, JSB22, JSB66 및 JSB89를 선발하였다. 선발된 6균주의 16S rDNA의 염기서열을 분석한 결과 HSB15는 L. alimentarius, JSA22는 L. plantarum, JSA57은 L. pentosus, JSB22는 L. brevis, JSB66는 L. alimentarius, JSB89는 L. parabrevis로 동정되었다. 항균 활성은 6균주 중에서 JSA22가 4개의 병원성균에 대한 항균을 나타내어 항균 활성이 가장 우수하게 나타났고, 인공위액 저항성은 HSB15, JSA22와 JSA57 균주가 70% 이상의 높은 인공위액 저항성으로 가장 우수했으며, 인공담즙 저항성은 HSB15를 제외한 5균주에서 80% 이상의 생존율을 나타내며 담즙액 저항성이 우수하게 나타났다. 또한 probiotic 특성을 지닌 분리 균주의 prebiotics로써 AOS를 이용한 성장율을 관찰한 결과, 모든 분리 균주가 AOS를 선택적으로 이용하며 성장하는 것을 관찰하였고 특히 JSB22가 AOS 이용 성장율이 가장 우수한 것으로 확인되었다. 본 연구를 통해 장류유래 probiotics를 선발하였고 AOS의 새로운 prebiotics로 활용을 검토한 바, synbiotics로 이용할 수 있는 가치가 있다고 판단되었다.