RESUMO
The purpose of this study was to examine the probiotic characteristics and selenium (Se) bioaccumulation potential of five Lactobacillus strains in vitro. Lactobacillus acidophilus, L. delbrueckii subsp. lactis, L. reuteri, L. gallinarum, and L. animalis were among the strains employed. As significant aspects of probiotics, identification, and evaluation of their survival potential in the gastrointestinal system were undertaken. Although all experimental Lactobacillus strains bioaccumulated Se (IV) concentrations in media culture, three Lactobacillus strains (L. animalis, L. gallinarum, and L. acidophilus) bioaccumulated the highest Se concentrations (23.08, 8.62, and 8.51 mg/g, respectively) after culture in the presence of 1.5 mg/ml sodium selenite. By disc diffusion, all isolates were evaluated for antibiotic susceptibility against six antibiotics, including ciprofloxacin, ampicillin, methicillin, streptomycin, tetracycline, and trimethoprim-sulfamethoxazole. Many of the isolates tested positive for resistance to some of the antibiotics utilized. The L. reuteri and L. gallinarum were found to be resistant to about 50% of the antibiotics that were tested. In terms of acid tolerance, L. animalis showed significant resistance at acidic pH by 1.72 log unit reduction whereas L. delbrueckii and L. galliinarum showed significant sensitivity at acidic pH (P > 0.05). Bile tolerance was addressed as an important aspect of the safety assessment for probiotics. There were variances in acid and bile tolerance among species, although all of them tolerated stress conditions to an acceptable degree. Upon comparing the various species, it was observed that L. gallinarum exhibited a significant decline in growth, as evidenced by a decrease of 1.39 log units in cell viability. On the other hand, L. acidophilus and L. animalis demonstrated remarkable bile tolerance, with 0.09 and 0.23 log unit reduction respectively (P < 0.05). These results suggest that L. animalis, L. gallinarum, and L. acidophilus, can be good candidates to evaluate them in vivo in further investigations due to their tolerance to acid, and bile, antibiotic resistance, and strong ability to bioaccumulate Se in chickens.
