Towards culturing anaerobic gut fungi from an avian herbivore

Abstract

Anaerobic gut fungi (AGF, phylum Neocallimastigomycota) are an understudied group of microorganisms that reside in the digestive tracts of herbivorous mammals and aid in plant biomass degradation. This degradation is facilitated by adhesion to the biomass and production of enzymes that break down complex sugars including cellulose. The presence of AGF in non-mammalian herbivores is not yet well understood, however, digestive tracts that promote fermentation are most likely to host AGF. One of few truly herbivorous birds, the ostrich, is a hindgut fermenter, with a very long colon and high retention time. These traits are strong indications that ostriches likely harbor AGF within their digestive tracts.

We hypothesized that ostriches represent not only a new host for AGF but likely also house novel AGF taxa. To test this hypothesis, we obtained fecal samples from four ostriches and are attempting to enrich and isolate known and novel AGF taxa. Using strict anaerobic techniques, a complex media amended with plant substrates, and antibiotics for bacterial growth suppression, we were able to enrich for AGF, which was visualized as hyphal filaments. We are currently undertaking procedures to isolate pure cultures for identification and characterization. Whether isolates are known or novel, isolation of any AGF from an avian host represents new knowledge gained about these understudied fungi. Culturing AGF from ostriches will allow for further understanding of how AGF evolved in non-mammalian hosts and expand their known evolutionary lineage.