Probiotic Potential of Lactic Acid Bacteria Isolated from Broiler and Indigenous Free-Range Chicken in Ethiopia

Abstract

In Ethiopia, poultry production is vital for enhancing the local economy, promoting food security, and alleviating poverty. However, the sector has faced significant challenges due to diseases and antibiotic resistance. This study aimed to isolate, evaluate, and characterize the probiotic potential of lactic acid bacteria (LAB) from the gut of chickens for their application as effective probiotics in poultry. Free-range indigenous chickens were sourced from local households in Bishoftu Town and its surroundings, while broiler chickens were from a commercial hatchery in the same area. The probiotic potential of the LAB isolates was assessed using standard protocols, with identification performed using Matrix-assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS). A total of 149 LAB were isolated and characterized. Nineteen of these isolates exhibited a broad zone of inhibition against all test bacteria, with the most significant inhibition observed against L. monocytogenes (21.33 ± 1.58 mm) and the least against S. Typhimurium (10.00 ± 1.00 mm). The survival percentages of six LAB isolates at pH levels of 2, 2.5, and 4 exceeded 82%, with survival rates above 84% observed at a 0.3% bile salt concentration. Additionally, adherence to the chicken gut ranged between 54% and 55% for the six LAB isolates tested. Notably, none of the isolates exhibited hemolytic activity. All heat-treated cell-free supernatants demonstrated antimicrobial activity against the test pathogens. However, the supernatants treated with pronase (isolates B12CA and B1I8) and those adjusted to pH 7 exhibited no antimicrobial activity. The MALDI-TOF MS presumptively identified the six LAB isolates as Lactobacillus reuteri DSM 20016T and Pediococcus pentosaceus DSM 20206. These lactic acid bacteria demonstrated potential probiotic attributes, making them effective supplements for managing enteric pathogens and improving chicken performance. Further analysis, including in vivo studies and molecular safety assessments, is necessary to evaluate the potential probiotics identified from the gut of free-range indigenous and broiler chickens for future applications.