Joblinomyces undulatus, sp. nov., a novel anaerobic fungus from the feces of a Boer goat.

Members of the phylum Neocallimastigomycota, often referred to as anaerobic gut fungi (AGF), primarily inhabit the gut of herbivorous animals. To date, 25 AGF genera have been described, but only five harbor more than one species. Here, we report on the isolation and characterization of novel AGF isolates from the feces of a Boer goat. The isolates formed small, mostly round, dense colonies on agar roll tubes and produced flaky, loosely clumped white biomass in liquid medium. Microscopic features included monoflagellated spherical zoospores and monocentric filamentous thallus. Sporangia were spherical or ovoid, although elongated and oddly shaped sporangia were also observed. Zoospore release was observed through ruptures in the sporangial wall. Phylogenetic analysis using the ribosomal internal transcribed spacer 1 (ITS1) and the 28S nuc rDNA D1-D2 region (28S) showed the isolates to be most closely related to Joblinomyces apicalis, the only described species in the genus Joblinomyces (0.00-1.30% divergence in ITS1, 2.50-3.82% in 28S). Transcriptomic sequencing and subsequent analysis of the RPB1 (largest subunit of RNA polymerase II) region and average amino acid identity (AAI) value comparison clearly showed a high level of AAI sequence divergence (70.11-75.40%, average 72.53 ± 1.43%) when compared with all other genera within the order Neocallimastigales. Based on morphological and phylogenetic analyses, we propose to accommodate these isolates as a novel species within the genus Joblinomyces and propose the name of Joblinomyces undulatus. The type strain for this species is JC3.3.