The Isolation And Characteristic Of A Moraxella Anas.sp.nov Strain From Ducks

Moraxella is a Gram-negative bacteria in the Moraxellaceae family, and often with a tendency to resist Gram decolorization. The organisms are commensals of mucosal surfaces and sometimes give rise to opportunistic infection. The organisms are short rods, coccobacilli. The rods are often very short and plump, frequently approaching a coccus shape, and the cocci are usually smaller occur as single cells or in pairs. Grow well under aerobic conditions, but some strains may grow weakly under anaerobic conditions. Colonies are not pigmented, oxidase and catalase positive. No acid is produced from carbohydrates. Usually highly sensitive to penicillin. The mol% G+C of the DNA is 40.0-47.5.The strain of Moraxella was isolated from ducks in Mianyang, Sichuan Area. The bacteria accompanied with Riemerella anatipestifer were isolated from ducks. We did the morphology, culture characteristics, growth characteristics and biochemical characteristics for the strain. Phylogenetic analysis based on 16S rRNA gene sequences indicates that strain belong to the family Moraxellaceae(moraxella) and shows the highest 16S rRNA gene similarity to Moraxella catarrhalis (97%). In the observations of microscope the organisms are short rods, cocci are usually smaller occur as single cells or in pairs. The isolated strains inoculated in the Chocolate Agar Plate grew well, and their bacterial colonies are smooth, flat, circular, convex with an entire margin and a moist-looking surface in the Chocolate Agar Plate. Growth does not occur on MacConkey agar. With the API 20NE kit, aesculin, gelatin and urea were not hydrolysed. Unassimilates glucose and malate,citrate,phenylacetate,L-arabinose,D-mannose,D-mannitol,N-acetyl-Dglucosamine, maltose, gluconate, caprate or adipate. Nitrate was not reduced. With the fermentation bacteria biochemical experiments the strain positive reaction for arginine, ornithine, lysine, citrate, urea, aesculin, xylose, oxidase, negative reactions for hydrogen sulfide, ONPG, glucose, sucrose, maltose, nitrate reduction, peptone water. Whole genome sequence of the strain was determined, and a complete genome sequence was obtained by sequence splicing. The length of the genome was 549960bpan and the mol% G+C of the DNA is 45.87%. Phylogentic tree constructed by 16S rRNA sequence of strains from different Moraxella can proved that the isolated strain was the bacteria of moraxella and they have the highest homologous identity with M. cunicul iand M. plranilmalium. To determine the relationship between this isolate and other Moraxella strains. We did the average nucleotide homology analyzed. The results showed that the ANIb value range was 69.23% ?74.21%, ANIm value range was 84.02?87.16%. The predominent respiratory quinone was MK-7 (92%), MK-6 (5%) and MK-8 (2%). The major polar lipids were diphosphatidyl(DPG), ethanolamine phosphatidyl (PE), glycolipid (GL), phospholipids unidentified (UPL) and aminophospholipids undentified (UAPL). On the basis of polyphasic analysis, the strain was considered as a novel species in the genus moraxella, for which the name Moraxella anas. sp. nov. (RCAD00137) poposed.For the further understanding of the biological characterization of the moraxella isolated from ducks. The infection test of animals made it clear that this isolated strain has enpathogenicity to ducklings, mice and duck embryo.Drug sensitivity test was used by K-B method. The results showed that the strain of Moraxella has a sensitivity to penicillinG, gentamycin, ampicillin, florfenicol, nalidixic acid, ciprofloxacin,enrofloxacin, erythromycin,clindamycin, spiramycin azithromycin, sulfamethoxazole, trimethoprim sulfamethoxazole, chloramphenicol and rifampicin was resistance, and sensitivity for imipenem, meropenem, ceftazidime. This strain showed multiple drug resistance. The minimum inhibitory concentration of quinolone drugs, lincosamide antibiotics, macrolide antibiotics, sulfonamide antibiotics were more than 512 ?g/ml, and showed highly resistant. The rest of the antibiotics showed low concentration of drug resistance.