| Probiotic are promising field for development of functional foods in the future lies in its important function on the host for its health benefit and prophylaxis disease. This experiment determined the potential functional properties of probiotic bacteria and its symbiosis in vitro and vivo in order to screen optimal combinative probiotic strains.Ten potential probiotics stains were tested in this experiment. Including two Lactobacillus acidophilus strains FBI and A878, two Bifidobacteria strains Pba and Inf, four Enterococcus strains Ml, PB2, A30, A31.one Bacillus abticisM2, one Clostridium butyricum strain was isolated from commercial probiotics by using TPY. The enterpathogens were bought from HeilongJiang Clinical Monitor Center, Including Escherichia coll, shigellosis, SalmonellaThe growth curve of nine probiotics were tested by monitoring OD620 of fermentative fluid, The result suggested that some strains had strong ability to producing acid including L. acidophilus PB1 and A878, Bifidobacteria Pba and Inf, the following were Enterococcus Ml PB2, A30, A31. But four Enterococcus grew quickly and hadn' t delaying period, the final period of logarithm growing of all tested strains were 12 hour for I acidophilus PB1 and A878; 24 hour for Bifidobacteria Pba and Inf; 8-10 hour for Enterococcus Ml, PB2, A30, A31 and Bacillus abticisM2The growth inhibition of Escherichia coli, shigellosis, Salmonell by the fermented liquor of eight probiotics bacteria was tested. The results suggested that the growth of three enterpathogens were strongly inhibited by L. acidophilus PB1 and A878, Bifidobacteria Pba and Inf. The diameter of inhibition zone was clear. But there were different ability of probiotics on inhibiting three enterpathogens. The inhibition mechanisms of PB1, A878, Pba, Inf were some organic acids and antibacterial substance in fermented liquor.L. acidophilus strains PB1, A878 mixed with Enterococcus strains Ml, PB2, A30, A31 respectively in the ratio of 1:1 in the MRS cultures, co-cultural and single liquor inhibition to the enterpathogens were tested in the terminal fermentation. The results suggested that L.acidophilus PBlgrew well with Enterococcus strains Ml, PB2, A30, A31.and had effective inhibition on the pathogens, the best combination were L.acidophilus PB1 with Enterococcus M1,A30. L.acidophilus A878 grew not well with Enterococcus strains Ml, PB2, A30, A31. The growth inhibition of enterpathogens was lower than L.acidophilus PB1. On the base of I.acidophilus strains PB1 mixed with Enterococcus strains M1, PB2, A30, A31, Bifidobacteria Pba and Inf were added in the culture.The results suggested Pba and Inf were limited on the co-cultures, its indicated that Pba and Inf grew badly with other probiotics in vitroEach mice were given 0.5ml fermentative liquor of probiotics strains PBl+A30,Pba, PB1,M1, PB1+M1,PB1+A30 for one month. The change of immune organs index and cytokine in the serum were tested. The results suggested that PB1+A30, PB1,PB1+Ml,Pba can improved the growth of spleen significantly with the spleen index enhanced 23.4%,29%,36.6% 23.6%(P<0.01). Amounts of IL-2 in the serum of mice of groups of Pba. PBK A30, PB1+M1were all significantly higher than control groups(P<0.05).The groups of Pba, PB1 can induced amount of IL-6 in the serum more than control groups(P< 0.01). All probiotic can improved amount of TNF-a(P<0.01). there were no difference in probiotics(P<0.01). PB1+M1, PB1+A30 Induced more amount TNF-A were 1.17ng/ml and 1.14 ng/ml respectively. The results indicated that probiotic had promoting effects to the immunity of mice.L.acidophilus strains PB1,A878 mixed with Enterococcus strains M1,PB2,A30,A31. The amounts of cholesterol removed from growth medium were tesed after anaerobical incubation at 37 CThe amount of cholesterol assimilated higher 40% by PB1+M1,PB1+PB2 A878+A30, A878+A31. The result indicated that PBlmixed with Ml, PB2 and A878 mixed with A30,A31 can assimilate cholesterol effectively. And the single strains PB1, A878, A30, A31 also can assimil...
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