Poster Presentation

In our study we had isolated Lactic acid bacteria (Lacticaseibacillus rhamnosus) from Ginseng sprouts, which is grown under 6 different LED conditions (Blue, IR, UV, Red, White, Dark) at smart farm. To collect culturable bacteria from Ginseng sprouts, the samples were freshly harvested & processed in 0.1% peptone buffer using sonication and blending. After that the different dilutions of buffer (10-1 to 10-6) were plated on MRS agar plates and then incubated at 370C for 72 hours. Approximately 485 bacterial colonies were isolated and then tested for BCP (Bromo Cresol Purple) test, Catalase activity and Gram staining. We found 35 isolates showed in BCP positive, Catalase negative and Gram positive. Among these 35 isolates, only five isolates were identified as Lacticaseibacillus rhamnosus by 16S rRNA sequencing.

This study aimed to isolate and characterize potential probiotics from Ginseng sprouts by evaluating their resistance to gastric acidity and bile salt, analyzing functional attributes, and then investigating the possibility of cholesterol-lowering levels through bile salt hydrolase (BSH) activity. In this study, we isolated 5 strains of Lacticaseibacillus rhamnosus and then conducted 0.3% bile tolerance test, acid tolerance test (pH=3), antimicrobial activity (against E. coli and S. aureus) and antioxidant activity (DPPH and ORAC assay) to certify probiotic potentiality. Viability against gastric acidity and bile salt ranged 6.85 ± 0.004 (log10CFU/ml) to 7.14 ± 0.009 (log10CFU/ml). Inhibition activity against E.coli and  S.aureus ranged 13.5 ± 0.17 mm to 15.24 ± 0.49 mm. The DPPH free radical scavenging activity around 53% ± 0.02. From these results, our isolated L. rhamnosus strains might serve as promising probiotic bacteria. Thus, we were going to experiment with bile salt hydrolase enzymatic activity in the agar plates. We expected that these 5 probiotic strains could display substantial bile salt hydrolase activity and also could reduce serum cholesterol levels from a laboratory growth medium.

Several cholesterol lowering pathways can be happened in the gastrointestinal tract by probiotics. Bile salt hydrolyzing (BSH) enzymatic activity is one of the potential pathways that is related with higher deconjugation of amino acids from conjugated bile salts and then this higher amount of deconjugated bile salts dehydroxylized into non-soluble deoxycholic acid and lithocholic acid that released from the body-thus reduced serum cholesterol level. BSH activity was verified by streaking on MRS agar plates supplemented with 0.5 %( w/v) TDCA with 0.37 g/l CaCl2. We studied viability against gastric acidity and bile salt ranged 6.85 ± 0.004 (log10CFU/ml) to 7.14 ± 0.009 (log10CFU/ml), inhibition activity against E.coli and S.aureus  ranged 13.5 ± 0.17 mm to 15.24 ± 0.49 mm, DPPH free radical scavenging activity around 53% ± 0.02 and 5 strains demonstrated BSH activity by white precipitation around colonies. As our isolated strains were probiotic potentials and initially showed BSH activity, we expected that these strains could display substantial bile salt deconjugation ability to reduce cholesterol from the body.

On February 24, 2022 at Korea Institute of Science & technology, I participated a symposium and presented an oral presentation about “Effects of Dietary Yeast Extract for Human and Animal Intestinal Health”. Yeast extracts are prebiotics and its effects on human and animal gut microbiota. I discussed how dietary supplementation of yeast extract influences the gut microbial community. Yeast extract can be produced by hydrolysis, plasmolysis, and autolysis. Yeast extracts contain yeast mannan, β-glucan, yeast nucleotides. These components are beneficial for gut microbial community.