Anaeromyces contortus, sp. nov., a new anaerobic gut fungal species (Neocallimastigomycota) isolated from the feces of cow and goat.

Ten different anaerobic gut fungal strains were isolated from fecal samples of cow and goat in Oklahoma, USA. The isolates displayed polycentric thalli, uniflagellated zoospores, and sausage-shaped hyphal constrictions, all characteristic of the genus Anaeromyces, and lobed or appressorium-like structures on the hyphae, previously reported in Anaeromyces elegans but not in A. mucronatus or A. robustus. Further, the strains exhibited highly coiled and entangled hyphae previously unreported in the Neocallimastigomycota, but resembling fungal traps previously observed in multiple nematophagous fungi. Scanning electron micrographs of isolates grown on switchgrass showed entrapment of plant material by the hyphal coils and the penetration of plant fibers at various sites by the appressorium-like structures. Molecular analysis based on sequences of both partial nuc rDNA ITS1 spacer region and the D1-D2 domains of the nuc28S rDNA confirmed the classification of all isolates in Anaeromyces and confirmed their phylogenetic distance from the available A. mucronatus and A. robustus sequences. On the basis of morphological and phylogenetic distinctions, we conclude that these strains represent a new Anaeromyces species, for which A. contortus is proposed.

A new anaerobic fungus (Oontomyces anksri gen. nov., sp. nov.) from the digestive tract of the Indian camel (Camelus dromedarius).

Two cultures of anaerobic fungi were isolated from the forestomach of an Indian camel (Camelus dromedarius). Phylogenetic analysis using both the internal transcribed spacer (ITS) and large-subunit (LSU) regions of the rRNA locus demonstrated that these isolates were identical and formed a distinct clade within the anaerobic fungi (phylum Neocallimastigomycota). Morphological examination showed that these fungi formed monocentric thalli with filamentous rhizoids and uniflagellate zoospores, broadly similar to members of the genus Piromyces. However, distinctive morphological features were observed, notably the pinching of the cytoplasm in the sporangiophore and the formation of intercalary rhizoidal swellings. Since genetic analyses demonstrated this fungus was only distantly related to Piromyces spp. and closer to the polycentric Anaeromyces clade, we have assigned it to a new genus and species Oontomyces anksri gen. nov., sp. nov. Interrogation of the GenBank database identified several closely related ITS sequences, which were all environmental sequences obtained from camels, raising the possibility that this fungus may be specific to camelids.

A highly active beta-glucanase from a new strain of rumen fungus Orpinomyces sp.Y102 exhibits cellobiohydrolase and cellotriohydrolase activities.

A new strain of rumen fungus was isolated from Bos taurus, identified and designated Orpinomyces sp.Y102. A clone, celC7, isolated from the cDNA library of Orpinomyces sp.Y102, was predicted to encode a protein containing a signal peptide (Residues 1-17), an N-terminal dockerin-containing domain, and a C-terminal cellobiohydrolase catalytic domain of glycoside hydrolase family 6. CelC7 was insoluble when expressed in Escherichia coli. Deletion of 17 or 105 residues from the N-terminus significantly improved its solubility. The resulting enzymes, CelC7(-17) and CelC7(-105), were highly active to ß-glucan substrates and were stable between pH 5.0 and 11.0. CelC7(-105) worked as an exocellulase releasing cellobiose and cellotriose from acid-swollen Avicel and cellooligosaccharides, and displayed a Vmax of 6321.64µmole/min/mg and a Km of 2.18mg/ml to barley ß-glucan. Further, the crude extract of CelC7(-105) facilitated ethanol fermentation from cellulose. Thus, CelC7(-105) is a good candidate for industrial applications such as biofuel production.

Caecomyces sympodialis sp. nov., a new rumen fungus isolated from Bos indicus.

A new anaerobic rumen fungus was isolated from the rumen fluid of a yellow cow (Bos indicus). This fungus appears to be a previously undescribed species of the genus Caecomyces, it possessing uniflagellate zoospores, a spherical holdfast, tubular sporangiophores and bulbous rhizoids. This new fungus also features distinctive multisporangiate thallus sympodially distributed on sporangiophores. The fungus resembles Caecomyces communis and C. equi in that it characterizes bulbous rhizoids and uniflagellate zoospores but differs from C. communis and C. equi in that it possesses multisporangiate and sympodial sporangia. This new fungus and Cyllamyces aberensis both reveal similar morphology during early thallus development in having a spherical holdfast, but they vary from unbranched sporangiophores and additional bulbous rhizoids. In addition, the molecular phylogenetic analyses ITS1 (internal transcribed spacer 1) also conform to the results of the morphological examinations of Caecomyces. For the mentioned reasons, this new species of fungus is described as Caecomyces sympodialis sp. nov. The genera of Neocallimasticaceae and species of Caecomyces are also keyed out.

Classical and molecular approaches as a powerful tool for the characterization of rumen polycentric fungi.

Ribosomal ITS1 and ITS2 fragments from 8 isolates of polycentric rumen anaerobic fungi were PCR-amplified and sequenced; the sequences obtained were aligned with published data and phylogenetic analyses were performed. Analysis of the ITS1 fragment clearly differentiated between the two polycentric genera Orpinomyces and Anaeromyces and this classification is supported by morphological observation. A multi-order phylogram based on ITS2 sequences proved that anaerobic rumen fungi are separated from aerobic chytrids, which form a well-supported monophylum with the highest possible bootstrap proportion values of 100%. Sequence analysis of ITS regions is a powerful tool for classification of anaerobic fungi but morphological description of strains is still necessary because some genera of rumen fungi display a high genetic heterogeneity.