Isolation of an unusual strain of Edwardsiella tarda from turbot and establish a PCR detection technique with the gyrB gene.
OBJECTIVE
The aim of this study was to report an unusual Edwardsiella tarda and develop an effective method to identify this bacterium.


RESULTS
During the spring and summer of 2006, an epizootic occurred among cultured turbot (Scophthalmus maximus) in Qingdao, China. A gram-negative, rod-shaped bacterium (designated as LTB-4) was isolated from the infected fish, and was proved to be virulent to turbot. Based on the 16S rDNA sequencing and phenotypic tests, the bacterial pathogen was identified as E. tarda. Unlike those commonly described E. tarda strains, no flagellate was observed. Partial gyrB genes were amplified from E. tarda using the universal primers of gyrB genes and sequenced. The polymerase chain reaction (PCR) primers for the gyrB gene were designed specific to E. tarda. It revealed positive amplification of the gyrB fragment in E. tarda, whereas other bacterial species were negative. In addition, the technique enabled the recognition of E. tarda from diseased fish.


CONCLUSIONS
The isolate was identified as E. tarda without flagellate and an effective method was developed to identify E. tarda based on using the gyrB gene as a taxonomic marker.


CONCLUSIONS
The unusual E. tarda was first reported in China and the PCR allowed the rapid and sensitive detection of E. tarda.
Lan
J
J
Department of Marine Biology, Ocean University of China, Qingdao, China.
Zhang
X-H
XH
Wang
Y
Y
Chen
J
J
Han
Y
Y
D000818:Animals; D015373:Bacterial Typing Techniques / Q000379:methods; D027081:DNA Gyrase / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D020609:Edwardsiella tarda / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D005393:Fish Diseases / Q000382:microbiology; D005412:Flatfishes / Q000382:microbiology*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014774:Virulence
D017931:DNA Primers; D012336:RNA, Ribosomal, 16S; D027081:DNA Gyrase