Identification Of Main Pathogen From The Chinese Giant Salamander (Andrias Davidianus) And Separation Of Antimicrobial Active Ingredient Of The Skin Secretion

With the expansion of farming scale and breeding density of the Chinese giantsalamander（Andrias davidianus）, its disease comes up continually.In order to investigate themain pathogen of the Chinese giant salamander, we acquire bacteria of differentcharacteristics from digestive tract of healthy giant salamander and lung, liver, abdominal andmuscle tissue of diseased giant salamander which we get them in hanzhong region of shannxiby conventional techniques of separating pathogens. Then we identify pathogenic bacteria bythe blast of16S rRNA gene sequences of bacteria strain, and analyze the pathogenicity ofsome bacteria. Meanwhile, We preliminarily separate antibacterial active ingredient from theskin secretion of giant salamander and detecte the inhibitory effect of the skin secretion toseveral bacterial. The main results are as follows:1， There are four main pathogenic bacteria from diseasedgiant salamander,they belong tothree different genus.They are Aeromonas hydrophilaand Aeromonas sobria ofAeromonas, Citrobacter freundii of Citrobacter,Edwardsiella tarda of Edwardsiella.2， We acquire Aeromonas hydrophila,Citrobacter freundii, Edwardsiella tarda,Cetobacterium somerae and Hafnia alveifrom digestive tract of health giant salamander.Cetobacterium somerae and Hafnia alvei are reported for the first time. Antibioticsensitivity testshowed that Hafnia alvei is the intestinal advantage bacteria. Drugsensitivity test showed that Hafnia alvei was high sensitive to Ciprofloxacin, Norfloxacin,Kanamycin, Acheomycin and Sulfamethoxazole, etc and the strain was not sensitive toStreptomycin, Furantoin and Amikacin etc. Animal pathogenicity test showed that whenCFU of Hafnia alvei are2.4x107, the strain had a certain Pathogenicity for crucian andmouse.3， This study also collected plenty of the skin secretion from the healthy giantsalamander. By sephadexchromatography and bacteriostatic test, we know that the skinsecretion own component which can inhibit Escherichia coli, and it may be anantibacterial peptide whose relative molecular mass is at about10kDa. And the ingredient also has inhibitory effect to the main pathogen isolated from giant salamanders.