Feramyces austinii, gen. nov., sp. nov., an anaerobic gut fungus from rumen and fecal samples of wild Barbary sheep and fallow deer

Anaerobic gut fungi are common inhabitants of the alimentary tracts of herbivorous animals. Nine different Neocallimastigomycota genera have been described so far. However, culture-independent diversity surveys suggest the presence of numerous, yet-uncultured Neocallimastigomycota genera. Here, we report on the isolation and characterization of the first cultured representatives of Neocallimastigomycota clade AL6, originally identified in culture-independent surveys of fecal samples from captive wild animals. Six strains were isolated from rumen and fecal samples of a wild Barbary sheep (Ammotragus lervia) and a wild fallow deer (Dama dama) in Texas, USA. The isolates displayed medium-sized (3-7 mm) circular beige colonies with filamentous edges and a dark center on agar roll tubes. Microscopic analysis revealed monocentric thalli with both endogenous and exogenous sporangial development patterns. Zoospores were spherical, with a diameter of 9.6 ±1.9 μm, and polyflagellated, with 7-16 flagella. Phylogenetic analysis based on nuc rDNA ITS1 region and D1-D2 domains of nuc 28S rDNA revealed that the isolated strains formed a single monophyletic and bootstrap-supported clade distinct from all currently described Neocallimastigomycota genera. Substrate utilization experiments using the type strain (F3a) demonstrated robust and fast growth on sugars and plant biomass, as well as the capability to metabolize a wide range of mono-, oligo-, and polysaccharides including galactose, arabinose, alginate, and pectin. On the basis of the morphological, physiological, and phylogenetic analyses, we propose to accommodate these isolates in a new genus Feramyces (derived from the Latin word for “wild” to reflect their isolation and apparent distribution in undomesticated herbivores), and a new species, F. austinii. The type species is Feramyces austinii strain F3a.