Preliminary Evaluation On Screening And Function Of Lactic Acid Bacteria From Pigs

With the constant development of green antibiotic substitutes and the continuous deepening of research on probiotics,the acquisition of good strains is particularly important.Lactic acid bacteria,as members of the family of probiotics,are of considerable value in the development and application of probiotics.This study screened porcine lactic acid bacteria isolated from pig cecum and feces,determined the optimal compound ratio of dominant lactic acid bacteria,and initially studied the effect of lactic acid bacteria compound preparation on the growth performance of mice and evaluated its function.Further lay the foundation for the lactic acid bacteria preparation as a new alternative to green antibiotics.The specific research content and results are as follows:1.Isolation,Identification and Primary Screening of Lactic Acid Bacteria from PigsThe intestinal contents and feces were diluted by multiples,and then coated on the MRS solid medium containing calcium carbonate to screen suspected Lactobacillus with calcium-solubilising loops,and passed preliminary identification by conventional Gram staining,biochemical experiments,etc.The species of 16Sr RNA was identified and the primary screening was performed by a rapid acid production test and the growth curve of the primary screening strain was measured.The results showed that 22 strains of lactic acid bacteria were isolated,including 2strains of Enterococcus faecalis,4 strains of Enterococcus faecium,4 strains of Lactobacillus salivarius,and 12 strains of Rhizoctonia.Acid production test results obtained L7-L11,L15,L19,L22,etc.8 more acid production,good growth performance of lactic acid bacteria from pigs.2.Screening of swine lactic acid bacteriaThe in vivo and in vitro environments were tested for heat,acid resistance(pH=2.5),bile resistance,artificial gastric juice resistance,and artificial intestinal fluid resistance.The strains were evaluated for their hydrophobicity,self-polymerization ability,and co-agglutination properties with pathogens.With performance,the strain was finally identified through comprehensive analysis of the inhibitory effects on three strains of E.coli CMCC44102,Staphylococcus aureus ATCC29523 and Salmonella paratyphi ATCC9150.L7 and L19 are two dominant swine lactic acid bacteria.3.The compounding and function evaluation of two strains of lactic acid bacteria from swineTwo strains of lactic acid bacteria of pig origin were tested in vitro according to different ratios,acid production test,antibacterial test to determine the optimal inoculum ratio,test its biosafety,mouse weight changes and other growth performance in vivo antibacterial and serum T-SOD and CAT indicators.The results showed that when L7:L19 was 3:1,the average body weight gain of the mice in the1.0×10~7 cfu/mL group was the most,but the difference was not significant(p>0.05);the antibacterial effect in the 1.0×10~8 cfu/mL group was the best in vivo.The T-SOD and CAT were significantly higher in the two groups(1.0×10~7 cfu/mL and 1.0×10~6cfu/mL)than those in other groups(p<0.05).The above results showed that from 22 isolates of lactic acid bacteria isolated from pigs,the combined preparations of L7 and L19 strains are safe and non-toxic,which can promote the growth of mice and increase the antioxidant capacity of mice,laying a foundation for further application in pig production.The foundation.