Isolation,Identification And Characterization Of Lactic Acid Bacteria In Rumen Of Shanbei White Cashmere Goats Under Combined Grazing And House Feeding

With the growing call for a global ban on the use of antibiotics,it is urgent to seek effective alternatives to antibiotics.Probiotics are widely used in livestock and poultry industry as green and safe additives,which can improve the microecological balance of the internal environment,accelerate the degradation and absorption of nutrients,and then enhance the disease resistance of animals.White cashmere goat breeding in northern Shaanxi is the pillar industry of agricultural and rural development in Yulin City,through the application of sheep probiotics,the implementation of non-antibiotic breeding,has important significance.The experiment was conducted to study the rumen microorganism of Shaanbei White Cashmere Goats under semi-grazing condition,and the rumen contents of healthy Shaanbei White Cashmere Goats were collected.The structure of rumen flora was analyzed by high-throughput sequencing technology,and the combination of MRS solid medium and MRS liquid medium was designed to isolate and screen rumen lactic acid bacteria according to the actual feeding situation.The isolated lactic acid bacteria were identified by Gram staining,biochemical test,molecular biology method,bacterial growth test,bile salt tolerance test and drug sensitivity test.To provide practical reference for the application of probiotics in goat production.The results are as follows:(1)Six samples of rumen contents of semi-grazing Shanbei white cashmere goats were collected,and 14 phyla,21 classes,30 orders,53 families,118 genera and 141 species were identified at different taxonomic levels by high-throughput sequencing.At the species level,there were 2 species of lactic acid bacteria in S1,8 species in S2,6 species in S3,3 species in S4,7 species in S5 and 5 species in S6.(2)Lactic acid bacteria were isolated from rumen by MRS medium,and 4 strains of bacteria were identified by physiological and biochemical tests and molecular biology.M-1was Lactobacillus mucosus,M-2 was Streptococcus equinus,M-3 was Lactobacillus plantarum,and M-6 was L.amylophilus.(3)Growth test,bile salt tolerance test and drug sensitivity test were used to study the biological characteristics of the isolated potential probiotic strains.Two strains of lactic acid bacteria with good characteristics were screened from the four isolated lactic acid bacteria,which were M-3 Lactobacillus plantarum and M-6 Lactobacillus amylophilus.To sum up,under the guidance of the results of high-throughput sequencing technology analysis of rumen flora structure,combined with the local feeding situation,a targeted isolation and identification method was designed,and two strains of lactic acid bacteria with excellent characteristics were isolated and screened,namely Lactobacillus plantarum and Lactobacillus amylophilus,which provided candidate strains for the study of sheep probiotics.