ATIVIDADE CELULOLÍTICA DE FUNGOS AEROBIOS ISOLADOS DO RÚMEN DE BOVINOS LEITEIROS ALIMENTADOS COM FORRAGENS TROPICAIS

Abstract

The objective was to evaluate the cellulolytic activity of aerobic mycelian fungi from dairy cat- tle fed tropical forages. Isolates of fungi were obtained from 30 samples of rumen fluid from cows fed sorghum silage, 32 cows fed on Brachiaria brizantha , 12 heifers receiving sorghum silage and 11 heifers fed cane sugar. The isolation was performed on C solid medium containing cellulose. Were evaluated 49 isolates, 27 Aspergil- lus spp., four Gliocladium spp., six Paecilomyces spp., nine Rhizophus spp. and three Scedosporium . These isolates were incubated in C medium with 1% microcrystalline cellulose as the sole carborno source, and incu- bated at 37°C in triplicate. Cellulolytic activity indices were verified after 24, 48 and 72 hours and calculated by the ratio between degradation halo and colony diameter for comparing in nonparametric tests. The genus Aspergillus , showed higher cellulolytic activity index mean compared to Rhizophus genus (p <0.05). Eight iso- lates of Aspergillus spp. and six of Paecilomyces spp. showed this index higher than one, indicating potential for utilization in ruminant nutrition.