Safety, environmental and technological characterization of beneficial autochthonous lactic bacteria, and their vaginal administration to pregnant cows for the design of homologous multi-strain probiotic formulas.

In recent years, veterinary probiotic formulations constitute an interesting alternative to the use of antibiotics in animals for human consumption, but beneficial microorganisms must meet certain requirements to be included in these products. The objective of this work was to evaluate the safety and innocuity of beneficial autochthonous lactic bacteria (BALB) as well as to determine their beneficial, environmental, and technological characterization. Antibiotic resistance was assayed using phenotypic and genotypic methodology. A bovine vaginal fluid simulated medium (MSBVF) was designed where growth, pH changes, and expression of beneficial characteristics of lactic bacteria were evaluated; additionally, the optimal culture conditions in commercial media were determined in order to obtain the highest biomass production of the strains. Finally, the best strains were lyophilized and administered intravaginally to pregnant cows and their permanence in the vagina and adverse effects were evaluated. The results show that most of the strains were resistant to vancomycin, tetracycline, and streptomycin, with a high sensitivity to ampicillin, gentamicin, and clindamycin. The strains evaluated did not show gelatinase or hyaluronidase activity; however, 11 strains produced α-type hemolysis. The optimal growth of the microorganism was obtained in MRS broth, under slight agitation and without pH control. The strains grown in the MSBVF grew well and maintained the probiotic properties. Animals treated with probiotics bacteria did not show systemic or local inflammation. These strains can be included in a probiotic veterinary product to be applied to different bovine mucosa.