Screening, Identification Of Probiotic Lactobacillus

As we know, northeast traditional fermented food was rich in a large number of lactic acid bacteria. 285 strains selected for this study, were isolated from the northeast traditional fermented pickle, northeast soybean samples.In this study,285 lactic acid bacteria strains in lab were selected for potential probiotics based on their tolerance in vitro gastrointestinal fluid, cholesterol reduction and antibiotic susceptibility. The identification of the probiotic strains including the shape identification, the physiological biochemical identification,16S rDNA sequencing analysis. The following were main results.1. Screening lactic acid bacteria for potential probiotics.(1) Lactic acid bacteria were selected based on their pH 3.0 tolerance and 0.3％(w/v) bile-salt resistance. Results showed 3 Lactic acid bacteria of N2, W1, N4 were preliminarily selected based on their highest potential with functional properties in vitro.(2) Wl showed the best survival abilities during human simulated gastric digestion, with 8.11％, 35.27％,90.18％of viable organisms respectively after 3h digestion in pH2.0, pH2.5, pH3.0 of gastric acid. The livability of N2 was 9.22％,26.15％,78.67％ respectively after 3h digestion in pH2.0, pH2.5, pH3.0 of gastric acid. N4 showed the lowest survival abilities with 1.40％,22.54％,62.88％ respectively after 3h digestion in pH2.0, pH2.5, pH3.0 of gastric acid.(3) N2,W1 showed better survival abilities during human simulated intestional digestion with 82.59％,86.02％of viable organisms respectively, N4 showed the lowest survival abilities with 74.71％.(4) Cholesterol-reducing tests were experimented on the 3 strains. The highest cholesterol removal (34.56%) was observed by W1 strain. The cholesterol assimilated from circumstances by N2, N4 strains were 27.12％,29.20％ respectively.(5) Antibiotic susceptibility test results showed a variation that, N2 strain was highly sensitive to penicillin and acetylspiramycin, and insensitive to streptomycin. W1 was highly sensitive to penicillin, streptomycin, moderately sensitive to acetylspiramycin. N4 was highly sensitive to penicillin, streptomycin, and acetylspiramycin.(6) According to the results, W1 was chosen as the best potential probiotic strains.2. Identification of the finally selected isolates.The screened isolates were identified as Lactobacillus plantarum with the shape identification, the physiological biochemical identification,16SrDNA sequencing analysis.