Screening, Characteristics And Application Of Lactobacillus Reuteri From Pigs

In order to explore new feed probiotic strains, 35 Lactobacillus reuteri strains was isolated from feces of health pigs.One excellent Lactobacillus reuteri strain was Screened by antibacterial test,acid resistance, and bile salt tolerance. This strain was identified as Lactobacillus reuteri.The biological characteristics and metabolic product of has been studied in this experiment. The effect of freeze dried strain on production performance of growing pigs was evaluated. The results were showed as follows:(1)One strain was successfully isolated from the faeces of healthy pigs, which had high producing acid ability, acid resistance, and bile salt tolerance. This strain was identified as Lactobacillus reuteri through standard morphological, biochemical, molecular tests.(2) The optimum growth temperature, growth pH value and inoculation amount of this Lactobacillus reuteri was 37℃,7.0 and 4%, respectively. The strain was reached stationary phases after 19 h, and the viable count was up 109 CFU/ml. The survival rate of this strain was up to 90% when incubated in artificial gastric juice at pH 2 and artificial intestinal juice for 2h, and was 78.13% for 4h. The survival rate of this strain was 76.82% when sustained at 65℃ for 1min. The supernatant and the bacterium liquid of this strain had inhibition to Escherichia coli, Salmonella choleraesuils, and Staphylococcus aureus. The bacteriostatic diameter reached 13.67-15.33 mm. The susceptibility test showed that Lactobacillus reuteri was insensitive to aminoglycoside, quinolone, large ring lactone, polypeptide, tetracycline, sulfa antibiotics, and sensitive to part penicillin and cephalosporin class. The highest lactic acid production was 3.17mmol/L. The extracellular polysaccharide was 334.61mg/L when cultured in MRS medium 48 h.(3) Animal feeding experiment showed that feed Lactobacillus reuteri supplementation(0.05%,0.15%,0.45%) increased daily gain 18.33%~23.10%(P<0.05), feed to gain ratio decreased 8.39%~11.61%(P<0.05). The Lactic acid bacteria in faeces was increased(P>0.05) and the E. coli and S.aureus counts/g faeces was significantly decreased(P<0.05) and(P<0.05) after Lactobacillus reuteri supplementation. In addition, the concentration of haptoglobin and urea nitrogen in serum was decreased significant(P<0.05) and lactic dehydrogenase and high density lipoprotein cholesterol was increased. These results showed that the supplementation of Lactobacillus reuteri in growing pigs’ s diet had improving effect on daily gain, feed to gain ratio, intestinal flora, body immunity and health.