Acanthuridae

Epulopiscium species are found in the gut of Acanthuridae, a family of tropical reef fishes that include surgeonfishes/tangs (Acanthurinae), unicornfishes (Nasinae), and sawtails (Prionurinae). Most Acanthurids are common on reefs in the Indo-Pacific Ocean, though some are found in tropical and subtropical areas around the world. This Family is distinguished by spines on the caudal peduncle (the base of the tail fin), which are used for defense or during aggressive behavior.


Many Acanthurids are conspicuous herbivores on the reef. They are often seen traveling in schools or small groups, deftly grazing on the substrate. They are found in shallow water where they can target the algae that thrive on hard surfaces like rock and coral rubble. Most Acanthurid species are primarily herbivorous, feeding on reef macroalgae, though some are planktivores or detritivores[v].

Evidence for Epulopiscium's Role

The prevalence of Epulopiscium species in herbivorous Acanthurid intestinal tracts suggests a role in digestion, though the exact nature of the symbiosis remains unknown. Epulopiscium·s kinship with other bacterial species that are obligate intestinal inhabitants and/or active in fermentation supports the theory that Epulopiscium species may contribute to the intestinal break down of food. Epulopiscium spp. are related to Clostridium species, which are intestinal inhabitants of a variety of organisms (including, but not limited to, humans[i], pigs[ii], freshwater fishes[iii], subtropical marine fishes[iv], and chickens[v]). Many Clostridium spp. can breakdown complex polysaccharides and ferment sugars. Even some clostridia isolated from the human gut have the ability to break down laminaran, a component of brown algae[vi]. Epulopiscium are also very closely related to Metabacterium polyspora, an intestinal symbiont of guinea pigs and other rodents[vii].


Initial results from the whole-genome sequencing of Epulopiscium have substantiated the idea that they function in the fermentation of food in Acanthurid intestinal tracts. So far, it seems that Epulopiscium species have genes for biochemical processes associated with the import and breakdown of polysaccharides. Further study of Epulopiscium and its genes will hopefully elucidate the spirit of this particular fish-microbe interaction.

Pictures:

http://www.reefwatch.asn.au/

http://www.earthscape.org/t1/mup01/mup01a_09.jpg   

http://www.imagequest3d.com

http://www.starfish.ch/collection/plants.html

http://hoopermuseum.earthsci.carleton.ca/Bermuda/maralga/BERM72B1.HTML

http://www.nmnh.si.edu/botany/projects/algae/Imag-Rho.htm

http://qualitywallpapers.x-istence.com

http://www.divekauai.com/seaguide.htm

http://animaldiversity.ummz.umich.edu/sitel/accounts/information/Cich idae.html

http://www.fishbase.org



Further Useful References and Links:

Clements, K.D. 1997. Fermentation and gastrointestinal microorganisms in fishes. In: Gastrointestinal microbiology. Vol. 1: Gastrointestinal ecosystems and fermentations (eds. R.I. Mackie and B.A. White). Chapman and Hall, New York, pp. 156-198

Crossman, D.J., J.H. Choat, and K.D. Clements. 2005. Nutritional ecology of nominally herbivorous fishes on coral reefs. Marine Ecology Progress Series 296: 129-142

Kendall Clements· Research Group http://www.sbs.auckland.ac.nz/research/ecolevol/clements/index.htm

Moran, D., S.J. Turner, and K.D. Clements. 2005. Ontogenetic development of the gastrointestinal microbiota in the marine herbivorous fish Kyphosus sydneyanus. Microbial Ecology 49(4): 590-597

Sale, P. (ed.) 1991. The ecology of fishes on coral reefs. Academic Press, San Diego.

[i] Kuiter, Rudie H. and Helmut Debelius. 2001. Surgeonfishes, Rabbitfishes, and their Relatives: A comprehensive guide to Acanthuroidei. TMC Publishing: Chorleywood, UK. 18
[ii] Lay, C., L. Rigottier-Gois, K. Holmstrøm, M. Rajilic, E. E. Vaughan, W. M. de Vos, M.D. Collins, R. Thiel, P. Namsolleck, M. Blaut, and J. Doré. 2005. Colonic microbiota signatures across five northern European countries. Applied and Environmental Microbiology 71(7): 4153-4155

[iii] Reid, C.A., K. Hillman, C. Henderson, and H. Glass. 1996. Fermentation of native and processed starches by the porcine caecal anaerobe Clostridium butyricum. Journal of Applied Bacteriology 80(2): 191-198

[iv] Sugita, H., J. Kawasaki, and Y. Deguchi. 1997. Production of amylase by the intestinal microflora in cultured freshwater fish. Letters in Applied Microbiology 24(2):105-108

[v]Moran, D., S.J. Turner and K.D. Clements. 2005. Ontogenetic development of the gastrointestinal microbiota in the marine herbivorous fish Kyphosus sydneyanus. Microbial Ecology 49(4): 590-597

[vi] Amit-Romach, E., D. Sklan, and Z. Uni. 2004. Microflora ecology of the chicken intestine using 16S ribosomal DNA primers. Poultry Science 83(7): 1093-1098 [vii]Fujii, T., T. Kuda, K. Saheki, and M. Okuzumi. 1992. Fermentation of water-soluble polysaccharides of brown-algae by human intestinal bacteria invitro. Nippon Suison Gakkaishi 58 (1): 147-152

[viii] Angert, E.R., A.E. Brooks, and N.R. Pace. 1996. Phylogenetic analysis of Metabacterium polyspora: clues to the evolutionary origin of the daughter cell production in Epulopiscium species, the largest bacteria. Journal of Bacteriology 178(5): 1451-1456