자돈의 분변으로부터 분리된 Lactobacillus 균주의 생균제적 특성에 관한 연구
(A) Study on the probiotics properties of Lactobacillus strains isolated from pig feces
자돈 Lactobacillus 생균제 축산학;
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Probiotics is a promising alternative to subtherapeutic use of antibiotics for swine feed and may be part of the solution for decreasing or eliminating antibiotic use in animal agriculture. The aim of this study was to isolate potential probiotic Lactobacillus strains from piglet feces. Three hundreds and fifty-three strains of Lactobacillus were isolated from fecal samples of 120 piglets which were raised at six different farms located in 4 different areas of Gyeongsangnam-do. Of these strains, eight strains selected for their resistance to low pH and higher bile acid in primary screening procedure were identified and further studied on their probiotic properties. When the strains were identified biochemically by using API CHL Kit, GSF3 was classified as L. plantarum with 78.3% confidence and other isolates 6-4, GJO2, GSD1, SMP2, SJD2, HD11-1 and SJG1 were L. fermentum with more than 90% confidence. But all of the eight selected strains were identified as L. reuteri by PCR identification using species-specific primer pair Lreu/Lrue4. The eight Lactobacillus reuteri strains all maintained their viability during incubation at pH 2.0 for 3 h and the strains 6-4, GSF3, GSD1, HD11-1 survived at pH 1.0 for up to 1 h when grown in the pH-adjusted MRS broth. All strains survived but incubated in MRS broth containing 5% bile salt. The strains all expressed higher bile salt hydrolase (BSH) activity than the commercial strains L. reuteri AVIBRO2. The eight strains were examined for their susceptibility to 11 antibiotics using a liquid medium dilution technique for minimal inhibitory concentration (MIC). The results have shown that the level of susceptibility to the antibiotics is strain-dependent. All strains except GSD1 were resistance to vancomycin. SMP2, SJD2, HD11-1, and SJG1 had an MIC value of >256 μg/ml for erythromycin. The commercial reference strains AVIBRO2 inhibited pathogenic bacteria more broadly. All of the eight isolates showed antimicrobial inhibition toward Staphylococcus aureus. Strains GJO2 and 6-4 inhibited the growth of Listeria monocytogenes. Strains 6-4 and GSF3 were more adhesive when the eight isolates were examined for adhesion using Caco-2 cell culture. Sterilized supernatant fluid from cell suspension (SSCS) of 6-4 and HD11-1 significantly affected the adhesion. 6-4 and GJO2 showed strong antiadhesion activity against L. monocytogenes and Bacillus cereus., respectively. In conclusion, Lactobacillus isolates may be regarded as a host specific and were regarded to be better adapted to survive and colonize the gastrointestinal tract of piglets because of resistance to low pH and higher bile acid and also, seemed to exert a probiotics properties such as antimicrobial activity against pathogens, adhesion activity to Caco-2 cells and adhesion inhibition activity against pathogens. Based on these results, Lactobacillus isolates would be used as probiotic strains for prevention of disease such as diarrhea and inflammation caused by pathogenic bacteria in piglets.