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Title: Biological characteristics and pathogenicity of a highly pathogenic Shewanella marisflavi infected sea cucumber (Apostichopus uaponicus)

item LI, HUA - Delian Fisheries University
item QIAO, GUO - Delian Fisheries University
item LI, QIANG - Delian Fisheries University
item ZHOU, WEI - Delian Fisheries University
item WOO, S.H. - Pukyoung National University
item Xu, Dehai
item PARK, S.I. - Pukyoung National University

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2010
Publication Date: 10/6/2010
Citation: Li, H., Qiao, G., Li, Q., Zhou, W., Woo, S., Xu, D., Park, S. 2010. Biological characteristics and pathogenicity of a highly pathogenic Shewanella marisflavi infected sea cucumber (Apostichopus uaponicus). Journal of Fish Diseases. 33:865-877.

Interpretive Summary: Shewanella are widely distributed in freshwater and marine environments and cause diseases of fish and aquatic animals. The information on virulence of Shewanella marisflavi to human and fishes is lacking. Thirty one bacterial isolates were collected from the diseased animals from 2004 to 2006. This study identified S. marisflavi isolates in laboratory, determined its biological characteristics and evaluated its pathogenicity to sea cucumber and swordtail fish. With the rapid increment of Shewanellaceae, the results in this study provide valuable information for identification, pathogenicity evaluation and industrial usage. Based on this study, the necessary measures are required to prevent S. marisflavi, which is currently found in the Yellow Sea in South Korea and diseased sea cucumber in China, expand to other geographic locations.

Technical Abstract: Shewanella marisflavi isolate AP629 was characterized as a novel pathogen of sea cucumber. The LD50 values (14 days) in sea cucumber and swordtail fish were 3.89 × 106 and 4.85 × 104 CFU g-1 body weight, respectively. Studies on S. marisflavi had been conducted, including morphology, physiological and biochemical characteristics, hemolysis, whole-cell protein and 16S rRNA gene sequence. Colonies of S. marisflavi appeared faintly red on MA and green on TCBS medium. S. marisflavi had polar flagella. The cells were gram-negative, oxidase- and catalase-positive and not sensitive to O/129. The bacterium exhibited ß-hemolysis on sheep blood agar and produced H2S. S. marisflavi survived and grew at temperature 4-35 ºC, pH 6.0-9.2, and in the presence of 0-8% NaCl. The whole-cell proteins included 13 discrete bands and proteins of molecular weight 87 kDa, 44 kDa and 39 kDa existed in all five strains of Shewanella spp. The difference in 16S rRNA gene sequences occurred at nucleotide 446 bp: S. marisflavi (KCCM 41822) - G, isolate AP629 - A, respectively. To our knowledge, this is the first report that Shewanella showed pathogenicity to sea cucumber. In respect of potential pathogenicity of Shewanella spp. to human and fish, more attentions should be paid in the handling of sea cucumber.