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为了确定导致美洲红鹮(Eudocimus ruber)肝脏血肿、出血性肠炎的病原,从美洲红鹮的肝脏、肠道和饲喂美洲红鹮的小黄鱼肠道内容物分离得到3株革兰氏阴性杆菌,并对其进行生化鉴定、药敏试验、小鼠致病性试验,同时观察死亡红鹮的组织病理学变化。结果表明,分离到的3株细菌通过生化鉴定均为嗜水气单胞菌(Aeromonas hydrophila),具有α溶血,药敏试验显示不属于耐药菌株,对小白鼠具有致病性。病理学诊断中,肝脏以血栓为主、肠道黏膜层多处出现肉芽肿。美洲红鹮因致病性嗜水气单胞菌导致死亡。

对北京麋鹿生态实验中心2只死亡的黑天鹅进行了临床分析、病理剖检及实验室检查，结果发现病变主要集中在心脏、肝脏和十二指肠，在肝脏等实质器官中分离到嗜水气单胞菌与肠致病性大肠埃希菌，在动物栖息环境的水体中也检测到致病菌存在，结合临床症状、流行病学分析、病理变化和病原检测结果等综合分析，确诊为嗜水气单胞菌与肠致病性大肠埃希菌混合感染。

在黑龙江省伊春林区捕获的呈“红腿病”体征的东北林蛙(Rana dybowskii),从其肝脏和腹腔积液中分离出一致病菌株RY-1,通过对分离菌株形态特征、生理生化、16S rDNA基因序列和系统发育树等分析进行菌种鉴定,并用该菌株RY-1人工感染健康东北林蛙后观察其肝脏组织病理学变化。结果显示,菌株RY-1形态呈浅黄色有光泽的圆形、中央凸起、边缘光滑、直径为1.5～2 cm的菌落,革兰氏染色阴性,16S rDNA的系统发育树等结果分析判定为嗜水气单胞菌(Aeromonas hydrophila)。随着感染时间延长(12～72 h),肝细胞变性,呈空泡样变,细胞间隙增大,炎性细胞浸润逐渐明显。本研究分离并鉴定了1株东北林蛙源嗜水气单胞菌,并首次探讨了人工感染嗜水气单胞菌的东北林蛙病理学变化,对其疾病防控和健康养殖具有重要参考意义。

DN322p, an offspring of Aeromonas hydro- phila DN322, has the capacity to adsorb and decolorize triphenylmethane dyes in wastewater simultaneously. As a common triphenylmethane dye, crystal violet （CV） was chosen to test the decolorization characteristics of DN322p. Within 0.5h, the strain DN322p adsorbed a large amount of CV, producing a deep-colored cell pellet and colorless supernatant. The colors of the cell pellet and supematant lightened over time. The supernatant and dichloromethane extract of the cell pellet both showed conspicuous CV and leuco CV （LCV） characteristic absorbance peaks at 590 nm and 260 nm, respectively, in the UV-vis spectral analysis. This finding indicated that the DN322p cells can adsorb the two dyes. A 99% （w/w） decolorization rate was achieved within 2.5 h with shaking at 30℃ for 50mg CV.L-1. High Performance Liquid Chromatography （HPLC） analysis of the dichloromethane extract of the supernatant and cell pellet confirmed that CV was mainly converted into its leuco form. Dead cells had a similar adsorption capacity with living cells. About 90% of CV in the dye solution （50mg-L-1） was removed by autoclaved cells with an optical delnsity at 600 nm （OD600） above 1.0.

[Objective]In order to carriy on effective medication and immune prevention and control,pathogen and etiology of a Rana spinosa David disease in a Rana spinosa David breeding company in Zhejiang was researched from 2009 to 2010. [Methods]Conventional bacteria separation and purification technology was used to purify pathogenic bacteria,regression infection and toxicity test was used to determine its virulence,physiological and biochemical and molecular biology identification was carried out to the the pathogen,k- b paper method was adopted for the susceptibility test,normal paraffin wax flaking technology was used for pathology observations,finally,the inactivation conditions of pathogenic bacteria was explored. [Results]The pathogenic bacteria separated from sick Rana spinosa David body had Median Lethal Concentration（ LC 50） of 5.62 ×105 cfu / ml; the strain was identified as Aeromonas hydrophila by ATB bacteria identification instrument and 16 s rRNA sequence analysis（ GenBank login number： HQ322682）; histopathology observation results showed that the disease had main symptoms of the liver and kidney damage,inflammatory cells increase. Susceptibility test showed that the strain was highly sensitive to gentamicin,norfloxacin,florfenicol,enrofloxacin etc. [Conclusions]1% formaldehyde could well inactivate the pathogenic bacteria at 60 ℃ for 24 h,which would provide technical reference for whole bacteria inactivated vaccine preparation.

Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community diversity in fresh and spoiled tilapia fillets stored at （4 ± 1）℃ and examined the antimicrobial activity of chitosan against relevant bacteria isolates. Results showed that Pseudomonas （20%） and Aeromonas （16%） were abundant in fresh tilapia fillets, whereas Pseudomonas （52%）, Aeromonas （32%） and Staphylococcus （12%） were dominant in the spoiled samples. Chitosan showed wide-spectrum antibacterial activity against bacteria isolated from tilapia and 5.0 g L-1 chitosan was selected for application in preservation. We further determined the shelf-life of chitosan-treated, filleted tilapia stored at （4 ± 1）℃ based on microbiological, biochemical and sensory analyses. Results showed that the shelf-life of chitosan-treated, filleted tilapia was extended to 12 d, whereas that of untreated, control samples was 6 d. These indicate that chitosan, as a natural preservative, has great application potential in the shelf-life extension of tilapia fillets.