In vitro fibrolytic potential of anaerobic rumen fungi from ruminants and non-ruminant herbivores

In the present study, anaerobic fungi were isolated from different ruminants and non-ruminants; i.e., cattle, buffalo, sheep, goats, wild bluebulls, elephants, deer, and zebras; and were identified as Anaeromyces, Orpinomyces, Caecomyces, Piromyces, and Neocallimastix sp., based on their morphological characteristics. These isolates possessed significant in vitro hydrolytic enzyme activities; however, an isolate of Caecomyces sp. from elephant was found to exhibit maximum activity, i.e., filter paper cellulase (Fpase; 21.4 mIU/ml), carboxymethyl cellulose (CMCase; 15.1 mIU/ml), cellobiase (37.4 mIU/ml), and xylanase (26.0 mIU/ml). Besides, this isolate also showed the significantly highest ability to digest plant cell-wall contents in vitro. The in vitro dry matter digestibility increased from 45.1 to 48.9% after 48 h of incubation, and the plant cellwall contents, in terms of neutral detergent fiber and acid detergent fiber, decreased from 64.2 to 61.3% and from 31.3 to 29.6%, respectively. These results indicate that such fibrolytic ruminal fungal strains are prevalent in wild herbivores such as elephants, as well as in other ruminants and non-ruminants, and could be exploited as microbial feed additives for improved nutrition and productivity in domesticated ruminants.