Aquimarina macrocephali

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A Microbial Biorealm page on the genus Aquimarina macrocephali

Classification

Higher order taxa

Bacteria; Bacteroidetes; Flavobacteria; Flavobacteriales; Flavobacteriaceae

Species

Aquimarina macrocephali

Description and significance

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Colony growth of Aquimarina macrocephali JAMB N27 [4]


A. macrocephali, is a Gram-negative, rod-shaped, non-spore forming, obligate aerobe that has gliding motility [3]. Colonies produce a vivid orange-red pigment, and are circular, smooth, glossy, and convex in shape. A. macrocephali requires a marine environment to survive, and can be most notably found in the Sea of Japan and the western Atlantic Ocean. Three different strains JAMB N27, JCM 15542, and NCIMB 14508. [2][4]

One major cause for interest in this microbe is in its pathogenicity to specific lobster species. At least one strain is known to cause epizootic lesions on American lobsters, which decrease their saleability and in some cases, cause death. [1]

Genome structure

A. macrocephali contains a single circular genome, with a G+C content of 33.1 mol%. The genome has been fully sequenced, and contains 6,056,210 base pairs [3]. 16S rRNA gene analysis shows high sequence similarity between multiple Aquimarina species: A. brevivitae showed a 94.2% similarity, A. intermedia showed a 95.9% similarity, and A. muelleri had the highest sequence similarity with a value of 97.3% [5].

Cell and colony structure

As a colony, A. macrocephali produces circular, smooth, shiny colonies that are 0.5 – 1.0mm in diameter. The preferred growth temperature is 25 °C, though growth will occur between 8 - 30 °C. Due to its gliding motility, there are no flagella present. A. macrocephali produces flexirubin pigments, which cause it to have its significant red-orange pigmentation when cultured. [4]

Metabolism

As a chemoheterotroph, A. macrocephali cannot fix carbon and must absorb carbon from organic compounds in its environment. It can hydrolyze cellulose, catalyze hydrogen peroxide into water and oxygen, and can hydrolyze starch into sugars. It is an obligate aerobe, and requires NaCl (2-4 % optimally) for growth. Without Na+ present, no growth is observed. A. macrocephali is unable to reduce nitrate, and cannot produce indole, acetoin, or H2S. [4]

Ecology

As a member of the genus Aquimarina, A. macrocephali requires a marine environment to survive. Notable locations it has been found in include Japan and the eastern United States. In most cases A. macrocephali is found near or on a marine animal, such as the within sediment adjacent to the carcass of a whale or on the shell of Homarus americanus [3]. Within a marine environment, the bacterium is usually found within depths of 100m - 250m. [4]

Pathology

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Epizootic lesion on Homarus americanus [2]


One subspecies, A. ‘homaria’, has been found to be a common pathogen to Homarus americanus. A. 'homaria' has been found to create epizootic and enzootic shell lesions by the excretion of harmful proteins that affect the calcium levels at the cuticle, and degrade the integrity of the outer shell layer. Virulence factors seem to indicate immunosuppression as a factor, but this is still highly debated. These lesions cause a multitude of problems, including molting issues, shell integrity issues, opening for further infection, and in severe cases can cause death. [2]


Within seafood markets, lobsters that have these lesions have an severely decreased saleability. This has heavily affected the North Eastern, U.S. lobster sales market in recent years. [1]

References

1) Bruce Phillips, "Lobsters: Biology, Management, Aquaculture & Fisheries, 2nd Edition" ISBN: 0470671130

2) Chistoserdov, Andrei Y., Robert A. Quinn, Sai Laxmi Gubbala, and Roxanna Smolowitz. "Bacterial Communities Associated with Lesions of Shell Disease in the American Lobster, 'Homarus Americanus Milne-Edwards." Journal of Shellfish Research 31.2 (2012): 449-62. Web.

3) Mcbride, Mark J. "The Family Flavobacteriaceae." The Prokaryotes (2014): 643-76.

4) Miyazaki, Masayuki, Yuriko Nagano, Yoshihiro Fujiwara, Yuji Hatada, and Yuichi Nogi. "Aquimarina Macrocephali Sp. Nov., Isolated from Sediment Adjacent to Sperm Whale Carcasses." Microbiology Society Journals, n.d. Web. 03 Nov. 2015.

5) Nedashkovskaya, O. I. "Description of Aquimarina Muelleri Gen. Nov., Sp. Nov., and Proposal of the Reclassification of [Cytophaga] Latercula Lewin 1969 as Stanierella Latercula Gen. Nov., Comb. Nov." International Journal Of Systematic And Evolutionary Microbiology 55.1 (2005): 225-29. Web.


Edited by Rachel Henson of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio