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.
Keywords: Creole bird; antimicrobial activity; antimicrobial susceptibility; lactic acid bacteria; probiotic potential.