Objective To isolate and identify Lactobacillus paracasei and Bacillus subtilis from feces of northern white geese.Methods Lactobacillus paracasei and Bacillus subtilis,numbered S00834-8 and IS00439-2 respectively,were isolated from feces of 30 52-week-old northern white geese and cultured in specific medium,and identified by 16S DNA sequencing.The two strains were cultured for different time duration(0,2,4,6,8,10,12,14,16,18,20,22,24,36 and 48 h),at different temperature(34,36,37,38 and 40 ℃)and pH(5.5,6.0,6.5,7.0,7.5 and 8.0).The growth characteristics of the strains were evaluated according to the A600 values measured by UV-Vis spectrophotometer.At the same time,the acid and bile salt tolerance(pH 2.0,2.5,3.0,3.5 and 7.0,bile salt concentration 0,0.3％,0.5％,1.0％and 1.5％)and the antibiotic tolerance were tested.Results The strains S00834-8 and IS00439-2 were Lactobacillus paracasei subspecies tolerance H and Bacillus subtilis KA9,respectively.The strain S00834-8 cultured under the optimum condition of the culture medium with pH 6.0,at 37 ℃,for 12 h,had good bile resistance and gastric acid resistance,which was moderately susceptible to piperacillin,norfloxacin,amikacin,gentamicin and tetracycline,and susceptible to levofloxacin,streptomycin and chlor-amphenicol.The strain IS00439-2 best cultured in the culture medium with pH 7.5,at 36℃,for 8 h,showed good bile resistance and gastric acid resistance,which was moderately sensitive to levofloxacin and tetracycline,while sensitive to piperacillin,norfloxacin,streptomycin and chloramphenicol.Conclusion Goose-derived Lactobacillus paracasei subspecies tolerance H and Bacillus subtilis KA9 have good acid resistance and bile salt resistance,which are expected to be candidate strains for goose-derived microecological preparations.
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