Identification and biological characteristics of pathogen Vibrio natriegen from clam Meretrix meretrix

Abstract:

A pathogenic bacterium(WT01)was isolated from diseased clam Meretrix meretrix Linnaeu,and was confirmed to be the pathogen of the epidemic by artificial infection experiment.The morphological,physiological and biochemical characteristics and 16S rRNA sequence were analyzed for this bacterium,and the relationship between reproduction of the bacterium and NaCl concentrations,pH and temperature were also determined.The results showed that the strain was gram negative,glucose fermented without gas production,oxidase positive,requiring sodium ions for growth,no pigment,non luminescence; It grew well on TCBS plate as yellow colonies and was sensitive to Vibrio inhibitor O/129.Therefore,it was confirmed that the strain belonged to the genus of Vibrio. The sequence analysis of 16S rRNA gene of WT01 and comparison with that of other related Vibrios showed that WT01 was very close to Vibrio natriegen,with a similarity of 99％.In conclusion,strain WT01 belonged to Vibrio natriege ,and the LD50 of the bacterium to M.meretrix was 5.5×106CFU/g(tested by Reed-Muench method).The sensitive test showed that the pathogen was sensitive to drugs such as norfloxacin(NOR), bactrim(SXT),ceftriaxone(CRO), cefobid(CFP),streptomycin(STR), chloromycetin(CMP) and cidomycin(GEN).Biochemical analysis was also done for its extracellular products.