关键词: 籽鹅; 植物乳杆菌; 耐受性; 抑菌活性; 益生菌制剂

Abstract: 【Objective】 This study was conducted to screen and isolate lactic acid bacteria from the cecum samples of healthy Zi geese as a candidate strain for the development of probiotics for geese. 【Method】 The isolated bacteria were isolated and identified by morphological observation,physiological and biochemical tests and 16S rDNA sequence analysis.The growth characteristics and pH curve,acid and bile salt resistance,heat resistance,osmotic pressure resistance,self-agglutination ability and surface hydrophobicity,antibacterial activity,drug sensitivity and safety were studied. 【Result】 A strain of Gram-positive bacteria was isolated from the cecum of healthy Zi geese.It was a small round colony with moist and smooth colony morphology on MRS medium,and was named DT021.The biochemical test results showed that it could ferment glucose,maltose,lactose,cellobiose,sucrose,raffinose,mannitol and esculin,the catalase and nitrate reduction tests were negative,and it was preliminarily determined as lactic acid bacteria.16S rDNA gene sequence analysis showed that the similarity between the isolated strain and 4 reference strains of Lactobacillus plantarum in NCBI was all 100%,and the isolated strain was identified as Lactobacillus plantarum.The growth curve and pH curve showed that the bacteria entered the logarithmic phase at 2 h,entered the stable phase at 16 h,pH decreased to below 4 at 18 h,and reached the lowest value of 3.82 at 32 h.The survival rates the isolated strain in MRS broth at pH 3.0 and 2.0 were 45.0% and 38.9%,respectively.The survival rates in MRS broth with 0.2% and 0.3% bile salt were 15.5% and 9.0%,respectively.After 50 ℃ water bath treatment,the survival rate was more than 50%,and the survival rate could reach 95.4% after 10% sodium chloride content broth treatment.The results of self-aggregation ability and surface hydrophobicity showed that the isolated strain was a moderately agglutinating and moderately hydrophobic strain.In addition,the isolated strain showed good antibacterial activity against five goose-derived pathogenic bacteria including Escherichia coli,Staphylococcus aureus,Salmonella,Proteus mirabilis,and Aerococcus viridans,and the diameters of the inhibition zone were all more than 13.5 mm.The results of drug test showed that the isolated strain was resistant to 6 drugs such as amikacin and norfloxacin,and was sensitive to β-lactam drugs.After 2 weeks of intragastric administration of the isolated bacteria liquid,there was no death or lesion in mice,indicating that the isolated strain had no toxic effect on mice. 【Conclusion】 Lactobacillus plantarum DT021 isolated in this study had good probiotic properties,and was safe and non-toxic side effects.It had potential development value in the field of goose probiotic preparations.

Key words: Zi goose; Lactobacillus plantarum; tolerance; bacteriostatic activity; probiotic preparations