DAO 91:223-235 (2010)  -  DOI: https://doi.org/10.3354/dao02254

Phenotypic and genetic characterization of bacteria isolated from diseased cultured sea cucumber Apostichopus japonicus in northeastern China

Hua Li1, Guo Qiao1, Jie-Quan Gu1, Wei Zhou1, Qiang Li1, Sung-Ho Woo2, De-Hai Xu3, Soo-Il Park2,*

1Key Laboratory of Mariculture and Biotechnology, Agriculture Ministry, PRC, Dalian Fisheries University, Dalian 116023, China
2Department of Aquatic Life Medicine, Pukyong National University, Busan 608737, Republic of Korea
3US Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Laboratory, Auburn, Alabama 36832, USA
*Corresponding author. Email:

ABSTRACT: During the winter–spring from 2004 to 2006 in northeastern China cultured Japanese sea cucumber Apostichopus japonicus suffered from a serious disease. Clinical signs included swollen mouth, skin ulceration and massive mortality. Clinical samples taken during this period were studied. Thirty-one bacterial samples were isolated from diseased sea cucumbers and identified through biochemical tests, 16S rRNA gene sequence analysis and PCR amplification, followed by pathogenicity determination. The results showed that the 31 isolates belonged to the genera Vibrio (64.5%), Shewanella (12.9%), Serratia (12.9%), Pseudoalteromonas (6.4%) and Flavobacterium (3.2%). The 3 prominent strains were Vibrio splendidus (41.9%), Shewanella (12.9%) and Serratia odorifera biogroup I (12.9%). Pathogenicity tests demonstrated that 13 out of 31 isolates were pathogenic, including 8 strains of V. splendidus, 3 strains of Shewanella sp. and 2 strains of Pseudoalteromonas tetraodonis. The pathogenic V. splendidus showed the highest frequency of appearance. Median lethal dose (LD50) values (14 d) of V. splendidus, Shewanella sp. and P. tetraodonis were 1.74 × 107, 7.76 × 106, 7.24 × 107 CFU g–1 body weight of sea cucumber, respectively. The virulences differed by species: Shewanella sp. > V. splendidus > P. tetraodonis. This is the first report of Shewanella sp. virulence in sea cucumber.


KEY WORDS: Sea cucumber · Apostichopus japonicus · Bacterial pathogen · Vibrio splendidus · Shewanella sp. · Pseudoalteromonas tetraodonis


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Cite this article as: Li H, Qiao G, Gu JQ, Zhou W and others (2010) Phenotypic and genetic characterization of bacteria isolated from diseased cultured sea cucumber Apostichopus japonicus in northeastern China. Dis Aquat Org 91:223-235. https://doi.org/10.3354/dao02254

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