Characterization, Antimicrobial Susceptibility and Hemolytic Activity of Chicken Gut Derived Lactobacillus spp. as Potential Probiotic Candidates
Abstract
Background: Gut health is essential for host well-being, with gastrointestinal microbial communities supporting digestion, nutrient absorption, immune modulation and pathogen defense. In poultry production, probiotics offer a promising alternative to antibiotics, addressing concerns about antimicrobial resistance, disease outbreaks and consumer demand for residue-free meat. This study aimed to isolate and characterize Lactobacillus spp. from different chicken gut regions- crop, proventriculus, ileum and caeca-and evaluate their safety through antibiotic sensitivity and hemolytic activity tests. Methods: A total of 40 isolates were obtained using De man-rogosa-sharpe (MRS) media under anaerobic conditions and purified through repeated sub-culturing followed by Phenotypic characterization, catalase test and carbohydrate utilization profiling. Molecular identification was performed by PCR amplification of the 16S-23S rRNA intergenic spacer region. Functional characterization involved assessment of antibiotic susceptibility using the kirby-bauer method and evaluation of hemolytic activity on sheep blood agar. Result: Lactobacillus isolates were identified based on Gram-positive morphology, catalase-negative activity and molecular confirmation using polymerase chain reaction. Carbohydrate fermentation profiles revealed distinct metabolic patterns across gut regions, indicating microbial specialization along the gastrointestinal tract. Antibiotic susceptibility testing showed a general trend of sensitivity to commonly used antibiotics such as penicillin, clindamycin, cefixime and chlortetracycline, while demonstrating intrinsic resistance to vancomycin, methicillin, streptomycin and kanamycin and frequent resistance to sulfonamides. Most isolates exhibited gamma hemolysis, suggesting low pathogenic potential. These results highlight that Lactobacillus spp. from the chicken gut are generally safe and metabolically diverse, but emphasize the importance of strain-specific screening for antibiotic resistance and virulence traits before their use as probiotics in poultry production.