Isolation and identification of Lactobacillus paracasei and Bacillus subtilis in goose feces
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.