Abstract
Direct-fed microorganisms (DFM) are recognized as an alternative to antibiotic-based growth promoters in poultry production due to their health benefits. DFM, however, should undergo rigorous safety testing to ensure they meet the criteria to be "Generally Recognized as Safe." This study assessed eight bacterial consortia (BC) isolated from the ileal and cecal intestinal regions of wild-type chickens, subjecting them to probiotic tests. Subsequently, they were spray- and freeze-dried to evaluate their storage stability for 30 days. BC5-I and BC7-I, isolated from the ileum, emerged as promising DFM, displaying a high content of Lactobacillales using a selective medium and higher susceptibility to Gram-positive and Gram-negative antibiotics. These BC showed a high tolerance to temperature (> 90%), pH > 4 (88-98%), and antagonist effects against Escherichia coli and Salmonella. BC5-I exhibited superior survival in the simulated gastric conditions and satisfactory intestine mucus adhesion. Freeze-drying was the best method to obtain BC5-I and BC7-I powders, with a survival efficiency of 80.3% and 73.2%, respectively, compared to the beginning of storage. BC5-I presented the lowest cell death rate and prolonged half-life through survival storage kinetics. BC5-I only contained Lactobacillus, and Limosilactobacillus reuteri was the predominant species in liquid (78.3%) and freeze-dried (59.8%) forms. BC5-I stands out as a promising Lactobacillus-based DFM that could improve chicken intestinal health and enhance meat and egg production.