Safety Characterization and Antimicrobial Properties of Kefir-IsolatedLactobacillus kefiri

Abstract

Lactobacilli are generally regarded as safe; however, certain strains have been associated with cases of infection. Our workgroup has already assessed many functional properties ofLactobacillus kefiri, but parameters regarding safety must be studied before calling them probiotics. In this work, safety aspects and antimicrobial activity ofL. kefiristrains were studied. None of theL. kefiristrains tested causedα- orβ-hemolysis. All the strains were susceptible to tetracycline, clindamycin, streptomycin, ampicillin, erythromycin, kanamycin, and gentamicin; meanwhile, two strains were resistant to chloramphenicol. On the other hand, allL. kefiristrains were able to inhibit both Gram(+) and Gram(−) pathogens. Regarding thein vitroresults,L. kefiriCIDCA 8348 was selected to performin vivostudies. Mice treated daily with an oral dose of 108CFU during 21 days showed no signs of pain, lethargy, dehydration, or diarrhea, and the histological studies were consistent with those findings. Moreover, no differences in proinflammatory cytokines secretion were observed between treated and control mice. No translocation of microorganisms to blood, spleen, or liver was observed. Regarding these findings,L. kefiriCIDCA 8348 is a microorganism isolated from a dairy product with a great potential as probiotic for human or animal use.