Isolation, Screening, And Application Of A Beneficial Lactobacillus From Sows

Using the general isolation methods for probiotics one excellent strain L. johnsonii XS4was isolated according to the criterion for Lactobacillus. The growth characteristics, fermentation technologys of L. johnsonii XS4and its effects on production performance of sows have been studied in this experiment. The results were showed as follows:1. One strain was successfully isolated from the faeces of healthy sows, which had high producing acid ability, acid resistance, and bile salt tolerance. This strain was identified as L. johnsonii though standard morphological, biochemical, molecular tests and named as L. johnsonii XS4.2. The optimum growth temperature and growth pH value of this L. johnsonii XS4was35℃and6.0～7.5, respectively. The optimum carbon nitrogen matching of this strain was2%sucrose+2%soy peptone+2%beef extract+0.75%yeast extract. The survival rate of this strain was up to59.94%when incubated in artificial gastric juice at pH2for2h, and was46.22%for4h. Artificial intestinal juice had inhibition to this strain. The survival rate of this strain was70.9%when sustained at65℃for60s, but was only4.77%at70℃for60s. The supernatant and the bacterium liquid of this strain had inhibition to Escherichia coli, Salmonella choleraesuils, and Staphylococcus aureus. The extracellular polysaccharide was309.39mg/L when cultured in MRS medium at pH6.5,35℃for48h.3. The formulation of protectant for lyophilized L. johnsonii XS4was optimized by means of response surface methodology. The results indicated that skimmed milk, trehalose and L-cysteine had significant influence on survival rate of bacterium. The optimal amounts in100mL of protectant formula were skimmed milk15.70g, trehalose7.68g and L-cysteine1.60g. The survival rate of L. johnsonii XS4was observed to be87.40%using the optimal compound protectant, which was very close to the expected value (87.26%).4. Sow feeding experiment showed that6.0×109CFU/kg feed L. johnsonii XS4supplementation increased litter weight at birth1.89kg (P<0.05),20d litter weight5.67kg (P<0.01), weaning litter weight7.04kg (P<0.05) and the number of piglets at weaning0.88(P<0.05) compared with control group. The E. coli and S.aureus counts/g faeces of treatment sows were decreased54.67%(P<0.01) and35.91%(P<0.05) compared with non supplement sows. In addition, the concentration of IgG in serum was increased14.68%(P<0.05) and alanine aminotransferase (ALT) was decreased17.19%(P<0.01) after L. johnsonii XS4supplementation. These results showed that the supplementation of L. johnsonii XS4in sow’s diet had improving effect on production and breeding performance.