Strict and facultative culturable anaerobic bacteria from the digestive tract of six American black vultures (Coragyps atratus Bechstein 1793) were isolated and identified. After capture, the birds received a noncontaminated diet for one week to eliminate possible allochthonous microorganisms. Then, specimens collected from tongue, stomach and intestines were weighed, submitted to decimal dilution in an anaerobic chamber, inoculated into culture media and incubated aerobically and anaerobically at 37ºC for enumeration, isolation and identification. Isolated bacteria were submitted to tests to detect possible antagonisms between them. The total bacterial population along the digestive tract ranged from 3.46 ± 0.39 log CFU/g in the stomach to 10.75 ± 0.37 log CFU/g in the distal intestine. Some bacteria were isolated for the first time from the digestive tract of C. atratus: Actinomyces bovis, Lactobacillus cellobiosus, Micrococcus luteus, Neisseria sicca, Clostridium bifermentans, Enterobacter agglomerans, Peptostreptococcus sp., Sarcina sp., Serratia odorifera, and Shigella flexneri. Associations between microorganisms were observed during isolation on two occasions, one involving A. bovis and N. sicca, and the other involving A. bovis and a Gram-negative rod. Hetero-, iso-and autoantagonisms were observed, suggesting the ecological role of these indigenous microorganisms in terms of population auto-control and environmental barrier in the digestive tract of carrionfeeding birds.

Heteroantagonismo entre estirpes de Enterobacter agglomerans isoladas de urubu (Coragyps atratus) como produtoras e Pseudomonas aeruginosa como reveladoras