Characterization of Autochthonous Strains from the Cecal Content of Creole Roosters for a Potential Use as Probiotics

SIMPLE SUMMARY: Although many countries have eliminated the use of antibiotics as growth promoters in poultry diets, more than 40 countries still use subtherapeutic antibiotics daily to reduce bacterial diseases triggered by the intensive production process, which has provoked microbial resistance and cross-resistance to other microorganisms. Thus, researchers continue to search for viable and feasible alternatives that also benefit the animals. Unquestionably, probiotics continue to be the main natural alternative. However, in many cases, the industry has rejected the use of these beneficial microorganisms due to the slight viability of bacterial strains and inconclusive results under different production conditions; thus, the use of native lactic acid bacteria from Creole birds, which have never been used as preventive antibiotics, may open up new tools for their widespread use in broiler production. This study showed that the isolation of Lactobacillus reuteri from the caeca of Creole roosters has high viability under different conditions of pH, bile salts, NaCl, and temperature, and in addition, this isolated bacterial strain strongly reduces the growth of pathogenic bacteria in vitro and has lower sensitivity to the use of three commonly used antibiotics, which allows their subsequent in vivo study in broilers. ABSTRACT: Five strains (CLP2, CLP3, CLP4, CLP5, and CLP6) were isolated from the cecal content of Creole roosters fed without antibiotic growth promoters. Biochemical and morphological tests (negative catalase and oxidase) confirmed the presence of lactic acid bacteria. Additionally, considering the 16s RNA, Lactobacillus vaginalis (CLP2, CLP3, CLP5, and CLP6) and Lactobacillus reuteri (CLP4) were identified. All strains (mainly CLP4 and CLP5) showed variable and significant growth (p < 0.001) at different levels of pH. Likewise, all bacterial cultures were quantified at 42 °C, although only strains CLP4 and CLP5 managed to grow at 30 °C. Additionally, the CLP4, CLP5, and CLP6 strains grew from 0.05 to 0.30% of biliary salts. However, only the CLP4 isolate grew at different concentrations of NaCl (2–10%), and CLP5 grew at 2% NaCl. The CLP4 strain was able to inhibit the in vitro growth of enterobacteria such as Escherichia coli ATCC(®) 11775TM, Salmonella Typhimurium ATCC(®) 14028TM, and Clostridium perfringens ATCC(®) 13124TM. In addition, CLP4 had lower sensitivity in the presence of amoxicillin and tetracycline compared to these pathogenic bacteria. Considering these in vitro results, it is necessary to carry out in vivo studies with the CLP4 strain to test the hypothesis of its probiotic effect in poultry.