DAO 61:169-174 (2004)  -  doi:10.3354/dao061169

Vibrio alginolyticus infection in the white shrimp Litopenaeus vannamei confirmed by polymerase chain reaction and 16S rDNA sequencing

Chun-Hung Liu1, Winton Cheng2, Jung-Ping Hsu3, Jiann-Chu Chen1,*

1Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan 202, ROC
2Department of Aquaculture, National Pingtung University of Science and Technology, Pingtung, Taiwan 912, ROC
3Pingtung Hsien Livestock Disease Control Center, Pingtung, Taiwan 900, ROC
*Corresponding author. Email:

ABSTRACT: A Gram-negative, rod-shaped bacterium identified as Vibrio alginolyticus was isolated from diseased Litopenaeus vannamei (also called Penaeus vannamei) in Taiwanese culture ponds. The diseased shrimp displayed poor growth, anorexia, inactivity, reddish pleural borders of antennae, uropods and telson, opaque and whitish musculature, and mortality. In histological preparations, melanized hemocytic granulomas were observed in the connective tissue around hemal sinuses together with hemocytic aggregation in necrotic musculature. Six isolates of Vibrio were collected from diseased shrimp at 3 farms, and these were evaluated for characteristics including morphology, physiology, biochemistry and sensitivity to antibiotics. The results indicated that the isolates belonged to a single species that grew in 1 to 8% NaCl, at 10 to 40°C and on TCBS (thiosulfate-citrate-bile sucrose) agar, and that gave positive catalase, O/F (Oxidation/Fermentation), lysine decarboxylase, gelatinase and cytochrome-oxidase tests. Identification of CH003 (1 of 6 isolates) was confirmed by PCR assay for V. alginolyticus (expected amplicon 1486 bp). The 16S rDNA sequence (GenBank accession number AY373027) gave 99.9% sequence identity to V. alginolyticus (GenBank accession number X74690). The calculated 96 h LD50 dose of the isolated strain was 3.0 × 105 colony forming units (CFU) shrimp-1 (6.6 × 104 CFU g-1).

KEY WORDS: Litopenaeus vannamei · Bacterial disease · Vibrio alginolyticus · PCR · 16S rDNA sequencing

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