Isolation, Screening, Characteristics And Application Of Lactobacillus Fermentum From Pig

The objective of this study was to isolate and identify the strain from feces ofheathy pig using traditional identification method and molecular biology method, andstudy the tolaerance capability to artificial gastrointestinal fluids, antibacterial ability,and adhesion properties of this strain. Atotal of160heathy piglets aged（35±2）dayswere selected to evaluate the effect of freezed-dried Lactobacillus fermentumsupplementation on weaned piglets. Piglets were divided into4groups with4replicates per group and10piglets per replicate. The dietary treatments consisted ofthe basal diet with no additive served, the basal diet with freeze dried Lactobacillusfermentum at0.1%,0.2%, and0.3%of diet, respectively. The trial lasted35days. Theresults were showed as follows:1）One strain was successfully isolated from feces of healthy pig and identifiedas Lactobacillus fermentum X6by traditional method and16S rRNA sequenceanalysis.2）The optimum growth temperature, growth pH and inoculation amount of thisLactobacillus fermentum X6was37℃,5.3and1%. The strain was reached stationaryphases during19h to36h. The optimum medium ratio for this strain was1.5%maltsugar,0.5%casein peptone,0.5%yeast extract and1.5%beef extract. The viablecount was up to4.82×109CFU/mL based on optimum medium. The survival rate ofthis strain was97.92%when incubated in artificial gastric juice at pH3for2h,86.46%for4h, and when incubated in artificial intestinal juice, it was84.68%for2h,and was75.68%for4h. The survival rate of this strain was99.19%,91.94%,80.65%when incubated at50℃,55℃,60℃for2min. The strain had inhibition toEscherichia coli, Salmonella choleraesuils, and Staphylococcus aureus, and thebacteriostatic diameter was11mm,12mm,11.33mm. The amount of adherence toCaco-2cell reaches940CFU/100cells at the liquid concentration of bacterium was109CFU/mL.3）The formulation of protectant for lyophilized Lactobacillus fermentum X6was optimized by means of orthogonal test. The results indicated that the optimal protectant formula were2%skim milk,1.5%monosodium glutamate,0.25%L-Cysteine,2%trehalose,1%lactose,1%sucrose,1%dextrin. The survival rate ofthis strain after freeze drying could reach83.17%using the optimal compoundprotectant.4）Animal experiment results showed that supplementation of Lactobacillusfermentum X6increased daily gain7.69%(P>0.05),15.38%(P<0.05),17.95%(P<0.05)compared with control group, while feed to gain ratio decreased8.37%(P<0.05),8.38%(P<0.05),3.91%(P<0.05), respectively. The Lactic acid bacteriain faeces of treatment groups increased0.34%(P>0.05),4.30%(P<0.05),1.13%(P>0.05) compared with control group, then the Escherichia coli decreased9.55%(P<0.05),21.77%(P<0.05),13.20%(P<0.05)compared with control group and theStaphylococcus aureus decreased0.51%(P>0.05),9.80%(P<0.05),4.22%(P>0.05)compared with control group. The IgG concentration of experimental groups washigher by8%(P>0.05),13.86%(P>0.05),11.1%(P>0.05) than the control group.