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Home • Piromyces sp. UH3-1 v1.0
A) Donkey host from which UH3-1was isolated. B) Roll tube used to
isolate individual axenic cultures of UH3-1. C) Individual mature
sporangia on corn stover (left) displaying ovoid structure. D)
Multiple sporangia, demonstrating the predominantly spherical to
ovoid structure; arrows indicate individual sporangia in
rhizomycelial network. E) DAPI stain indicating the monocentric
nature as zoosporatic nuclei are contained with the sporangia. F)
Uniflagellated zoospore of UH3-1 Photo credit: Ethan Hillman,
Purdue University (Adapted from <a
href="https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-018-1292-8">Hooker 
et. al., 2018</a>) used under a <a
href="https://creativecommons.org/licenses/by/4.0/">Creative Commons
Attribution 4.0</a> License.
A) Donkey host from which UH3-1was isolated. B) Roll tube used to isolate individual axenic cultures of UH3-1. C) Individual mature sporangia on corn stover (left) displaying ovoid structure. D) Multiple sporangia, demonstrating the predominantly spherical to ovoid structure; arrows indicate individual sporangia in rhizomycelial network. E) DAPI stain indicating the monocentric nature as zoosporatic nuclei are contained with the sporangia. F) Uniflagellated zoospore of UH3-1 Photo credit: Ethan Hillman, Purdue University (Adapted from Hooker et. al., 2018) used under a Creative Commons Attribution 4.0 License.

Piromyces sp. UH3-1 (proposed name Piromyces indianae) is an obligate anaerobic fungus (phylum Chytridiomycota, class Neocallimastigomycetes). Anaerobic fungi are commonly found within the digestive tracts of ruminants and hindgut fermenters (large herbivores), where they provide nutrition to the host animal by digesting fiber-rich plant substrates. UH3-1 was isolated from the feces of a donkey (Equus africanus asinus) in Independence, Indiana in 2016. The species is monocentric, possessing a single oval zoosporangium, which develops dozens of zoospores in a life cycle similar to other members of Chytridiomycota. The zoosporangium also develops an extensively branched rhizoidal system devoid of nuclei that grows invasively into plant material. UH3-1, and other anaerobic fungi, are of particular interest as they secrete a wide array of fungal- and bacterially-sourced carbohydrate active enzymes (CAZymes) for hydrolysis of plant cell walls (Solomon et al, 2016, Haitjema et al, 2017). Secreted CAZymes are tailored to plant composition: UH3-1 growth and CAZyme activity is not hindered by the type of lignin present in the plant substrate, unlike many other fungi, suggesting that they are able to recognize and adapt well to varying plant cell wall structures (Hooker et al, 2018). The genome of UH3-1 will aid in the discovery of novel CAZymes that are better suited to specific components of lignocellulosic biomass including enzymes more robust to lignin composition. Furthermore, the genomes will enable future systems biology characterization of the genetic and epigenetic regulatory strategies these fungi use to adapt to substrate composition, ultimately paving the way for strain optimization and development.

References:

Haitjema, C. H. et al. A parts list for fungal cellulosomes revealed by comparative genomics. Nature Microbiology 2, 17087 (2017).

Hooker, C. A. et al. Hydrolysis of untreated lignocellulosic feedstock is independent of S-lignin composition in newly classified anaerobic fungal isolate, Piromyces sp. UH3-1. Biotechnology for Biofuels 11, 293 (2018).

Solomon, K. V. et al. Early-branching gut fungi possess a large, comprehensive array of biomass-degrading enzymes. Science 351, 1192–1195 (2016).