牛蛙脑膜脓毒性黄杆菌病病原的研究

报道了对牛蛙脑膜脓毒性黄杆菌病的病原进行分离、培养、人工感染、生理生化、药物敏感等试验研究,结果确认引起该病的病原菌为脑膜脓毒性黄杆菌(Flavobacteriummenigosepticum).该病的治疗宜采用诺氟沙星、红霉素、磺胺嘧啶钠等药物.

牛蛙脑膜炎脓毒性黄杆菌病

牛蛙脑膜炎脓毒性黄杆菌病陈耀明，胡永强，周以凤（上海动植物检疫局，２０００３２）蔡玉书，方德强（上海市奉贤县畜牧兽医站，２０１４００）１９９３年８月，上海市奉贤县某牛蛙养殖场爆发一种蛙病，大批牛蛙（包括亲蛙、成蛙、幼蛙和蝌蚪）染病死亡。经临床诊断、病...

Efficient Amplification and Sequence Analysis of aroA Gene Sequence of Flavobacterium johnsoniae through TAIL-PCR

[Objective] The aim was to study the sequence of aroA gene （synthetic gene in metabolic pathway of aromatic amino acids） of a pathogenic bacterium （Flavobacterium johnsoniae） causing gill-rote disease.[Method] Genomic DNA of strain M165 of F.johnsoniae was used as a template,three specific nested primers of 5＇end and 3＇end and arbitrary primer were used to amplify the aroA gene of strain M165 through Thermal asymmetric interlaced PCR （TAIL-PCR）.And the obtained sequence was analyzed.[Result] The electrophoresis determination result showed that the size of amplified product was consist with the expected product; sequencing analysis suggested that the full-length of aroA gene was 1 230 bp,enconding 410 amino acids.The amino acid sequence of aroA protein showed the highest level of similarity to amino acids sequence of aroA protein of F.johnsoniae.[Conclusion] TAIL-PCR provided a simple and efficient new method for the cloning of the gene sequence.Obtaining of full-length of aroA gene provided a foundation for further investigation on the effects of nutrition correlation factors such as aroA on the virulence of and virulence of F.johnsoniae.

Antagonistic Endophytic Bacteria Isolated from Different Growth Stages of Cotton for the Control of Cotton Verticillium wilt

[Objective] This study aimed to investigate the combined control effects of endophytic bacteria at different growth stages against cotton Verticfllium wilt and pro- vide a new strategy for the biocontrol of other soil-borne diseases. [Method] Endophytic bacteria with high resistance against Verticillium wilt were isolated from seedling, squaring and boll-setting cotton vascular, respectively. Their 16S rDNA se- quences were detected for comparative analysis. Three biocontrol strains were se- lected and identified, whose colonization roles in cotton plants were explored. The control efficiency was determined with indoor and field experiments. [Result] Accord- ing to the 16S rDNA sequence homology, the three strains were identified as Paeni- bacillus polyrnyxa YUPP-8, Paenibacillus xylanilyticus YUPP-1 and Bacillus subtilis YUPP-2, respectively. Results of colonization assessment showed that three strains all could be successfully colonized in cotton vascular. However, application amount had a positive effect on the number of colonized biocontrol bacteria in cotton, strain YUPP-8 had the largest number of colonized biocontrol bacteria in seedling period, strain YUPP-1 had the largest number of colonized biocontrol bacteria in squaring period, and strain YUPP-2 had the largest number of colonized biocontrol bacteria in boll-setting period. Indoor pot experiment showed that cotton plants in combined bio- control bacteria treatment group were not infected in flowing period, while Verticillium wilt morbidity rate of cotton treated with single strain in seedling period were 6.7% （YUPP-8）, 6.7% （YUPP-1） and 13.3% （YUPP-2）; however, Verticillium wilt morbidity rate wilt of the control reached 80%. Field experiment conducted during 2010-2011 showed that the combined application of three strains had better effect than separate application; specifically, Verticillium wilt morbidity rate and disease index of cotton in boll-setting period with combined application of three strains in 2010 were 9.4% and 6.5, respectively, while those in control group were 47.5% and 32.8; results in 2011 were similar to 2010, with higher disease severity. These results indicate that com- bined application of endophytic bacteria at different growth stages has great applica- tion potential in control of cotton Verticillium wilt. [Conclusion] This study preliminarily overcomes the defects in the application of biocontrol bacteria and provided reference for the prevention and treatment of other soil-borne diseases.

Involvement of two glycoside hydrolase family 19 members in colony morphotype and virulence in Flavobacterium columnare

Flavobacterium columnare is the pathogenic agent of columnaris disease in aquaculture. Using a recently developed gene deletion strategy, two genes that encode the Glyco hydro_19 domain （GH19 domain） containing proteins, ghd-1 and ghd-2, were deleted separately and together from the F. columnare G4 wild type strain. Surprisingly, the single-, Aghd-1 and Aghd-2, and double-gene mutants, Aghd-1 Aghd-2, all had rhizoid and non-rhizoid colony morphotypes, which we named Aghd-1, Aghd-2, Aghd-1 Aghd-2, and NAghd-1, NAghd-2, and NAghd-1 Aghd-2. However, chitin utilization was not detected in either these mutants or in the wild type. Instead, skimmed milk degradation was observed for the mutants and the wild type; the non-rhizoid strain NAghd-2 exhibited higher degradation activity as revealed by the larger transparent circle on the skimmed milk plate. Using zebrafish as the model organism, we found that non-rhizoid mutants had higher LDs0 values and were less virulent because zebrafish infected with these survived longer. Transcriptome analysis between the non-rhizoid and rhizoid colony morphotypes of each mutant, i.e., NAghd-1 versus （vs） Aghd-1, NAghd-2 vs Aghd-2, and NAghd-1 Aghd-2 vs Aghd-1 Aghd-2, revealed a large number of differentially expressed genes, among which 39 genes were common in three of the pairs compared. Although most of these genes encode hypothetical proteins, a few molecules such as phage tail protein, rhs element Vgr protein, thiol-activated cytolysin, and TonB-dependent outer membrane receptor precursor, expression of which was down-regulated in non-rhizoid mutants but up-regulated in rhizoid mutants, may play a role F. columnare virulence.