Neocallimastigomycota

Neocallimastigomycota
Scientific classification
Kingdom:	Fungi
Division:	Neocallimastigomycota M.J. Powell 2007[1]
Class:	Neocallimastigomycetes M.J. Powell 2007[1]
Order:	Neocallimastigales J.L. Li, I.B. Heath & L. Packer[2]
Family:	Neocallimastigaceae
Type genus
Neocallimastix (I.B. Heath 1983) Vavra & Joyon
Genera
Anaeromyces Caecomyces Cyllamyces Neocallimastix Orpinomyces Piromyces

Neocallimastigomycota is a phylum of anaerobic fungi, found in the digestive tracts of herbivores. It encompasses only one family.^[1]

Discovery

The fungi in Neocallimastigomycota were first described by Orpin in 1975,^[3] based on motile cells present in the rumen of the sheep. Although the cells were first believed to be flagellates, it has since been shown that they are fungi related to the core chytrids. Prior to this, the microbial population of the rumen was believed to consist only of bacteria and protozoa. Since their discovery they have been isolated from the digestive tracts of over 50 herbivores, including ruminant and non-ruminant mammals and herbivorous reptiles.^[4][5]

Reproduction and growth

These fungi reproduce in the stomach of ruminants through the use of zoospores that bears a kinetosome but lacks the nonflagellated centriole known in most chytrids,^[1] and have been known to utilize horizontal gene transfer in their development of xylanase (from bacteria) and other glucanases.^[6] The nuclear envelopes of their cells are notable for remaining intact throughout mitosis.^[1]

Metabolism

Neocallimastigomycota lack mitochondria. Using hydrogenosomes to oxidize NADH to NAD+, they release H₂ as a product.^[6]

Polysaccharide-degrading activity

Neocallimastigomycota play an essential role in fibre-digestion in their host species. They are present in large numbers in the digestive tracts of animals which are fed on high fibre diets.^[7] The polysaccharide degrading enzymes produced by anaerobic fungi can hydrolyse the most recalcitrant plant polymers and can degrade unlignified plant cell walls entirely.^[8][9] The polysaccharide degrading enzymes are organised into a multiprotein complex, similar to the bacterial cellulosome^[10]

Spelling of name

The Greek termination, "-mastix", referring to "whips", i.e. the many flagella on these fungi, is changed to "-mastig-" when combined with additional terminations in Latinized names.^[11] The family name Neocallimastigaceae was originally incorrectly published as "Neocallimasticaceae" by the publishing authors which led to the coinage of the misspelled, hence incorrect "Neocallimasticales", an easily forgiven error considering that other "-ix" endings such as Salix goes to Salicaceae. Correction of these names is mandated by the International Code of Botanical Nomenclature, Art. 60. The corrected spelling is used by Index Fungorum.^[12] Both spellings occur in the literature and on the WWW as a result of the spelling in the original publication.

References

1. ^ ^{a b c d e} Hibbett, D.S., et al. (March 2007). "A higher level phylogenetic classification of the Fungi". Mycological Research 111 (5): 509–547. doi:10.1016/j.mycres.2007.03.004. PMID 17572334. 
2. ^ Li, J.L., et al. (1993). "The phylogenetic relationships of the anaerobic chytridiomycetous gut fungi (Neocallimasticaceae) and the Chytridiomycota. II. Cladistic analysis of structural data and description of Neocallimasticales ord. nov.". Can. J. Bot. 71: 393–407. 
3. ^ Orpin CG (December 1975). "Studies on the rumen flagellate Neocallimastix frontalis". J. Gen. Microbiol. 91 (2): 249–62. PMID 1462. 
4. ^ Ljungdahl LG (March 2008). "The cellulase/hemicellulase system of the anaerobic fungus Orpinomyces PC-2 and aspects of its applied use". Ann. N. Y. Acad. Sci. 1125: 308–21. doi:10.1196/annals.1419.030. PMID 18378601. 
5. ^ Mackie RI, Rycyk M, Ruemmler RL, Aminov RI, Wikelski M (2004). "Biochemical and microbiological evidence for fermentative digestion in free-living land iguanas (Conolophus pallidus) and marine iguanas (Amblyrhynchus cristatus) on the Galápagos archipelago". Physiol. Biochem. Zool. 77 (1): 127–38. doi:10.1086/383498. PMID 15057723. 
6. ^ ^{a b} C.J. Alexopolous, Charles W. Mims, M. Blackwell, Introductory Mycology, 4th ed. (John Wiley and Sons, Hoboken NJ, 2004) ISBN 0-471-52229-5
7. ^ Ho YW, Bar DJS (1995). "Classification of anaerobic gut fungi from herbivores withemphasis on rumen fungi from Malaysia". Mycologia 87 (5): 655–77. doi:10.2307/3760810. JSTOR 3760810. 
8. ^ Akin DE, Borneman WS (October 1990). "Role of rumen fungi in fiber degradation". J. Dairy Sci. 73 (10): 3023–32. doi:10.3168/jds.S0022-0302(90)78989-8. PMID 2178175. 
9. ^ Selinger LB, Forsberg CW, Cheng KJ (October 1996). "The rumen: a unique source of enzymes for enhancing livestock production". Anaerobe 2 (5): 263–84. doi:10.1006/anae.1996.0036. PMID 16887555. 
10. ^ Wilson CA, Wood TM (1992). "Studies on the cellulase of the rumen anaerobic fungus Neocallimastix frontalis, with special reference to the capacity of the enzyme to degrade crystalline cellulose". Enzyme .Microb. Technol. 14: 258–64. doi:10.1016/0141-0229(92)90148-H. 
11. ^ combform3.qxd
12. ^ Suprafamilial Names

External links

• MeSH Neocallimastigomycota
• NIH