Study On The Evaluation Of Feed Enterococcus Faecalis And Bacillus Subtilis In Vitro

Now in the process of swine industry in china, the treatment of intestinal infections mainly relies on antimicrobials, but it has some obvious disadvantages, such as bacte-rial resistance, environmental pollution, drug residues and so on, directly endanger human health. With the banning on growth-promoting_antimicrobials_in European and the increase of health awareness and environmental awareness of national, the use of antimicrobials in China will subject to certain restriction. so developing safe feed additive that no pollution, no residue, no resistance is the direction of livestock industry.In this study, generation time and susceptibility of Enterococcus Faecalis (E.faecalis) and Bacillus subtilis (B. subtilis) were performed.In addition,the effect of E.faecalis, B. subtilis on the growth of Escherichia coliO54(E.coli), Salmonella choleraesuis A72 (S.choleraesuis) and normal bacterial Lactobacillus acidophilus CICC6075 (L. acidophilus) were also detected.The generation time of E.faecalis and B.subtilis were 23.9 and 29.4mins under the condition of 37℃, used LB medium. The results showed that they growed rapidly.Minimum inhibitory concentration for Lincomycin(LCM), Enrofloxacin(ENR), Sulfadiazine(SD),Streptomycin Sulfate(SM),Ampicillin Sodium Salt(AMP), Tiamulin fumarate(TML), Tylosin(TYL), Florfenicol(FLO), Polymyxin B Sulfate (PLM), Cef-tiofur Hydrochloride(CTX) and Doxycycline(DC) against E.faecalis and B.subtilis were performed by broth macrodilution,the CLSI reference method. The results showed that the MICs of these drugs against E.faecalis were 64,0.5,>256,64,4,256, 4,4,>256,256,<0.625μg/mL, according to the corresponding standards, E.faecalis were resistant to SD, TML, LCM, CTX, LCM, SM, PLM and sensitive to ENR, FLO, DC, AMP, indicating that SD, TML, CTX, LCM, CTX, LCM, SM and PLM had the compatible application with E.faecalis, but not ENR,FLO,DC,AMP. The MICs of these drugs against B.subtilis were 16,0.125,>256,8,16,256,2,2,256, 32,0.5μg/mL, According to the corresponding standards, B.subtilis were resistant to SD,TML,CTX,LCM,SM,PLM and sensitive to ENR,TYL,FLO and DC, indicating that SD, TML, CTX, LCM, SM and PLM had the compatible application with B.subtilis, but not ENR,TYL,FLO and DCThe effect of E. faecalis and B. subtilis on growth of the pathogenic E. coli, S. choleraesuis and normal intestinal bacterial L. acidophilus were tested by mixed culture. The results showed that the growth of E.Coli and S. choleraesuis could be well inhibited by E.faecalis and B.subtilis. E.faecalis could promote the growth of L. acidophilus. However, L.acidophilus could be inhibited by B.subtilis in the pre-35h of mixed culture, and then, they could be promoted growth well.