Seleção de bactérias láticas com potencial probiótico para uso como veículos vacinais orais contra a Leptospirose Canina

Abstract

Lactobacilos are Gram-positive bacteria, catalase negative, capable of fermenting glucose and other sugars with its final major product been lactic acid. They must have several characteristics to make them potentially good candidates as antigenic vehicles for oral vaccines and as good probiotics. Seventy nine bacteria were isolated from the feces of Chinese Crested and Yorkshire Terrier puppies, around 20 days old, and were submitted to molecular identification at the genus level. Of these, 37 were identified at the species level as Lactobacillus, and submitted to probiotic characterization. In order to evaluate the ability of the lactobacilli isolates to overcome gastrointestinal challenges, the bacteria were tested for susceptibility to the acidic pH 2.5 found in the stomach and bile salts found in the small intestine; most of the bacteria were resistant to acidic pH and showed slight to moderate growth inhibition by bile salts. The potential for adhesion to the hydrophobic surfaces of intestinal epithelia was indirectly evaluated by the capacity of the isolate to be associated with organic solvents, highlighting 7 isolates with highly hydrophobic cellular surfaces. Most of the isolates showed strongly antagonistic activity against the seven bacterial pathogens tested; however, the isolates tested against Leptospira interrogans serovar Icterohaemorrhagiae showed no zone of inhibition to pathogen growth. The vast majority of the isolates (34/37) tested showed themselves to be producers of hydrogen peroxide, an antimicrobial substance associated with vaginal colonization. Through all of the results obtained, it was possible to select 7 lactobacilli isolates as potential probiotics that could be used as vehicles for oral vaccinations.