Cellulolytic activity of anaerobic facultative fungi from the digestive tract of sheep fed with banana leaf hay

Résumé

Cellulose degradation is an important process for obtaining energy in the rumen of animals raised with fibrous foods and for the microbiological industry. In this study, the cellulolytic activity index (CAI) of aerobic mycelial fungi from the digestive tract of sheep was evaluated. A total of 30 lambs were raised in an intensive system, distributed in a completely randomized design, with five diets and six replications. Gradual replacements of Cynodon ssp. hay by banana leaf hay were promoted. Approximately 15 mL of ruminal content and swabs from the rectal ampoule were collected. The cultures were carried out in C medium, containing microcrystalline cellulose; and the mycelial fungi isolates were identified after the microculture technique. Among the fungi from rumen fluid, 23 isolates corresponded to the genus Aspergillus and three to Paecilomyces. Seven Aspergillus spp. and three Paecilomyces spp. were identified to samples of rectal ampoule. The Aspergillus genus predominated among the isolates (P <0.05). Fragments of fungus isolates were inoculated in triplicate in medium C at 37°C and the CAI was determined after 24, 48 and 72 hours of incubation. Differences between the CAI of Aspergillus spp. isolates from animals in different diets were not detected (P >0.05). Twenty-two isolates of Aspergillus spp. and three Paecilomyces spp. isolated produced CAI > one, indicating biotechnological potential for cellulase production.