Isolation And Identification Of Bacillus Licheniformis And Its Feeding Effect On Broilers

This experiment was conducted to isolate a stain of Bacillus from guts of broilers in wild ecosystem and study its feeding effects on broilers.The ileo-ceacal mucosa of a healthy broiler in wild ecosystem in Hainan province was collected,homogenized and centrifugated.After being sequentially treated by water bath at 65℃for 45 minutes,by Simulated Gastric Fluid and Simulated Intestinal Fluid at 37℃for 24 hours,the supernatant was streaked on MH plate at 37℃ for 24 hours.One of the several clones from MH plate was isolated and fermented,and its fermentation broth was found to have inhibitory effect on Aeromonas hydrophila,Edwardsiella tarda,Salmonella choleraesuis,Actinobacillus pleuropneumoniae and Streptococcus suis,with broad-spectrum antibacterial activity.It was identified as Bacillus licheniformis and named as Bacillus licheniformis L strain(BLL)by 16S r DNA sequencing analysis.Subsequently,animal feeding experiment was conducted.1260 fourty eight-day-old healthy Mahuang male broilers were randomly divided into 7 groups(A,B,C,D,E,F and G)with 4 replicates of45 birds each,and fed 7 experimental diets respectively for 4 weeks.The 7 experimental diets were the basal diet supplemented with Bacillus licheniformis L at 0,10~1,10~2,10~3,10~4,10~5and 10~6CFU/g respectively.At the conclusion of the feeding experiment,one bird from each replicate of A,B,D,F and G group were randomly selected for serum,small intestine and cecum sampling to determine the serum physiological and biochemical indexes,structure of small intestine villi and caecum bacterial grouping.The results of the experiments showed that:(1)the supplementation of BLL at 10~5～10~6CFU/g significantly increased the average daily feed intake and average daily weight gain of broilers(P<0.05);(2)the supplementation of BLL at 10~3～10~6CFU/g significantly reduced the intensity of immune response(P<0.05)improved the antioxidant capacity of broilers(P<0.05);(3)the supplementation of BLL at 10~3～10~6CFU/g significantly increased the diversity and the relative abundance of Bacteroides,Oscillospira,Ruminococcus,Faecalibacterium,Megamonas and Lactobacillus of cecal flora in broilers at a certain degree.The above results showed that it was suitable to add 10~5CFU/g of Bacillus licheniformis L strain to broiler diet.When the dosage is 10~5CFU/g,it can improve the average daily feed consumption and weight gain of broilers,weaken the intensity of immune and anti epidemic,improve the anti-oxidation ability of broilers,increase the diversity of cecal flora of broilers,to a certain extent,it can improve the relative abundance of probiotics in the flora and reduce the relative abundance of harmful flora in the flora.