First report of Shewanella sp. and Listonella sp. infection in freshwater cultured loach,Misgurnus anguillicaudatus

A novel disease outbreak occurred among cultured loach, Misgurnus anguillicaudatus in China. The diseased fish displayed lethargy, loss of appetite, black discolouration, anasarca and ventral skin hyperaemia. Clinical signs were observed in most of the fish examined, which consisted of discoloured liver, swollen spleen and petechial haemorrhage in the intestine and peritoneal membranes. The causative agent was found to be two species of bacteria by experimental infection, identified as Shewanella sp. and Listonella sp. The result showed that these were likely to be Shewanella putrefaciens and Listonella anguillarum respectively. Bacterial identification consisted of physiological and biochemical tests as well as 16S rRNA sequence analysis. In addition, antibiotic susceptibility testing was performed, revealing that Shewanella putrefaciens and Listonella anguillarum were susceptible to enrofloxacin, ciprofloxacin, levofloxacin, pipemidicacid and norfloxacin. This is the first report of S. putrefaciens and L. anguillarum from cultured loach.     

Occurrence of multiple antibiotic resistance and genotypic characterization in Edwardsiella tarda isolated from cage‐cultured hybrid red tilapia (Oreochromis sp.) in the Ping River,Northern Thailand

Edwardsiella tarda is a pathogen that causes edwardsiellosis in aquatic animals. The emergence of multiple antibiotic‐resistant strains makes antibiotic treatment difficult. This study aimed to investigate the antibiotic susceptibility patterns and the genotypic characterization of E. tarda isolated from cage‐cultured red tilapia in Thailand. A total of 30 isolates were identified as E. tarda using biochemical and molecular analysis. The disc diffusion method for testing antibiotic susceptibility showed all the isolates were resistant to colistin sulphate and oxolinic acid. High levels of resistance to amoxicillin, ampicillin, ceftazidime, oxytetracycline and sulphamethoxazole/trimethoprim were observed as well. The multiple antibiotic resistance index ranged from 0.25 to 0.92, indicating that these isolates had been exposed to high risk sources of contamination where antibiotics were commonly used. All the isolates carried the bla_TEM gene based on polymerase chain reaction (PCR). The tetA and sul3 genes were detected in 90% (27/30) and 26.7% (8/30) of the isolates respectively. Nine different genetic groups of isolates were obtained using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC‐PCR). A correlation between genetic types and multiple antibiotic‐resistant patterns was found. These results highlight the potential risks of multiple antibiotic‐resistant isolates for humans and the environment.     

不同来源嗜水气单胞菌耐药基因检测

采用PCR方法,对分离于唐山和秦皇岛养殖场的宽体金线蛭(Whitmania pigra)、中国林蛙(Rana temporaria chensinensis)、牙鲆(Paralichthys olivaceus)、草鱼(Ctenopharyngodon idellua)、青鱼(Mylopharyngodon piceus)以及鲤(Cyprinus carpio)肝脏的42株不同水产养殖动物的致病性嗜水气单胞菌(Aeromonas hydrophila)进行了4种耐药基因β-内酰胺类(TEM)、氨基糖苷类(ant(3″)-I)、磺胺类(Sul3)和四环素类(tet(A))的检测。结果表明:42株嗜水气单胞菌均100%携带TEM、ant(3″)-I和Sul3,不携带tet(A)。所检不同水产动物源嗜水气单胞菌均携带TEM、ant(3″)-I及Sul3耐药基因,从分子层面表明该致病菌多重耐药或潜在耐药严重。     

球等鞭金藻三级培养过程中细菌群落多样性分析

球等鞭金藻三级培养过程中生长差异明显,在完全灭菌的一级培养中生长最佳,在未灭菌的三级培养中生长最差。为揭示培养过程中藻际细菌群落多样性与其生长差异的相关性,以球等鞭金藻(Isochrysis galbana)为研究对象,利用Illumina HiSeq平台通过高通量测序的方法对球等鞭金藻三级培养过程中细菌群落多样性进行研究。结果表明,一、二、三级培养组之间的藻际细菌群落组成差异明显。Shannon和Simpson指数分析说明,一级培养组中细菌群落多样性显著低于二级和三级培养组。MetaStat分析发现,一级和三级培养组之间存在两株丰度显著差异的细菌,其中麦氏交替单胞菌(Alteromonas macleodii)在三级培养下丰度显著高于一级,而红球菌(Rhodococcus erythropolis)相反。进一步通过2216E平板涂布法分离并鉴定了麦氏交替单胞菌等17株球等鞭金藻藻际环境细菌;系统进化树构建结果显示,整个进化树分成13个分支,分别对应13个属,包括交替单胞属(Alteromonas)、假交替单胞属(Pseudoalteromonas)、海杆菌属(Marinobacter)等。本研究结果为探索藻菌互作机理奠定了基础,有助于提高水产养殖过程中球等鞭金藻的产量和质量。     

南美白对虾双茬淡化养殖技术研究

研究采用南美白对虾塑料大棚保温三级淡化暂养技术等措施,实现南美白对虾池塘双茬淡化养殖。养成期间水质情况良好,水温平均（26±3）℃,pH值约8．5左右,溶氧量5．6m叽以上,氧氮约0．20mg/L,亚硝酸氮0．02m班左右,每667m^2养殖产量达426．7kg,养殖效益高达4186．7元。结果表明,采用南美白对虾双茬淡化养殖技术,延长了对虾生长期,提高了池塘利用率和经济效益,具有较好的推广价值.     

水产品等食品中磺胺类抗生素残留分析与预处理方法的研究进展

对水产品等食品中磺胺类抗生素常用的分析方法和预处理方法进行了综述,归纳和比较了毛细管电泳法、微生物方法、液相色谱-质谱法、免疫法、气相色谱法、分光光度法、高效液相色谱法等特点。其中高效液相色谱法由于操作简便、快速、灵敏、准确的特点,是当前检测磺胺类抗生素的主要方法。同时,对包括固相萃取、分子印迹等预处理方法进行了综述。     

Comparison of 2 methods for establishing rat model of chronic osmotic diarrhea

AIM: To compare 2 different rat models of chronic osmotic diarrhea with the lactose enrichment and magnesium citrate methods. METHODS: The SD rats (n=31) were randomly divided into lactose enrichment diarrhea group (Lac group, 12 rats), magnesium citrate diarrhea group (Mg group, 12 rats) and normal control group (Con group, 7 rats). The rats in Lac group were fed with a lactose enrichment diet and freely drank water. The rats in Mg group were fed with a standard diet and drank magnesium citrate solution. The Con group was fed with a standard diet and normal water. The general conditions and the characteristics of stool were observed every day. The grip strength and motor activity of the rats were measured after diarrhea for 14 d. The trans-epithelial resistance of the colonic mucosa was detected by Ussing chamber. The pathological changes of villus height and villus surface area in the intestine were observed with hemato-xylin-eosin staining. RESULTS: The rats in both diarrhea groups displayed the clinical manifestations of slow increase in body weight, spare and dull hair, lacking in strength and physical inactivity. The grip strength and motor activity of the rats in both diarrhea groups decreased significantly compared with Con group. The diarrhea rate and diarrhea index of the rats in the 2 diarrhea groups were both significantly higher than those in Con group (P<0.05). Moreover, the diarrhea index in Lac group was significantly increased compared with Mg group. The thickness of intestinal mucosa in Lac group was thinner than that in Mg group at the same time. However, the damage of intestinal villi in Mg group was more serious than that in Lac group.CONCLUSION: Both methods of lactose enrichment-induced diarrhea and magnesium citrate-induced diarrhea meet the requirement of chronic osmotic diarrhea, but there are different advantages between the diarrhea models. Therefore, we should select the correct diarrhea model to meet different aims of the experiments.     

女贞枸杞散预防断奶仔猪腹泻效果和对血液白细胞数的影响

为探讨以女贞子、枸杞子、穿心莲、大青叶等多味中药组成的"女贞枸杞散"对断奶仔猪腹泻的预防效果和对外周血各类白细胞数量的影响。根据体重相近、公母各半的原则选用80头体重为10kg左右的"杜长大"三元杂交断奶仔猪,随机分4组,分别为试验Ⅰ组(日粮中加0.4%"女贞枸杞散"),Ⅱ组(添加0.6%),Ⅲ组(添加0.8%)和对照组(普通日粮)。详细记录仔猪腹泻情况,计算腹泻率、腹泻频率、腹泻指数等。试验结束后采血,测定各类白细胞数量,结果表明,"女贞枸杞散"能有效地降低断奶仔猪的腹泻率,改善仔猪的生长性能,促进血液中的白细胞尤其是淋巴细胞的的生成,提高机体免疫力。     

Erwinia amylovora populations resistant to oxolinic acid in Israel: prevalence, persistence and fitness

Oxolinic acid (OA) has been the only bactericide used against fire blight in pear and quince orchards in Israel since 1998. OA-resistant Erwinia amylovora strains (Ea-OA^R) were detected in several orchards in two restricted areas in the northern Galilee region during 1999–2001. In the following years, resistant strains could not be detected in some of these locations. Documenting the fate of Ea-OA^R strains in commercial orchards at eight sites in northern Israel during 2000/03 revealed that the resistant population appeared irrespective of the number of sprays applied and the severity of the disease. The persistence of the Ea-OA^R populations varied from site to site, ranging from 4 to 20 months; these differences could be attributed to the fire blight management activities of growers. Comparative studies on the fitness of Ea-OA^R and E. amylovora strains sensitive to OA (Ea-OA^S) were conducted in vitro and in planta using two strains of each group. In four of the six comparisons, disease incidence on detached blossoms inoculated with Ea-OA^S was significantly higher than that on blossoms inoculated with Ea-OA^R. In two experiments conducted on 8-year-old pear trees grown under netting, the colonization of Ea-OA^S in blossoms, annual shoots and perennial spurs was significantly higher than that of the Ea-OA^R. In two experiments conducted on 2-year-old trees grown under netting in an experimental station, the incidence of shoots exhibiting fire blight symptoms and the rate of symptom progress within the branches were significantly higher in trees inoculated with Ea-OA^S than in those inoculated with Ea-OA^R. The results of this study suggest that OA-resistant E. amylovora strains have lower fitness than wild-type strains. These findings may have implications for fire blight management.     

新疆蕨类植物的抗菌活性初探

对新疆９种苦头类植物孢子叶或营养叶的抗菌活性进行了生物测定,试验结果表明有６种苦头类植物孢子叶或营养叶对１－２种细菌具有较强的抑制作用,而对真菌均无抑制活性。