实验性鸡绿脓杆菌病的病理学研究

对30例实验感染绿脓杆菌病鸡的主要脏器进行了眼观和病理组织学观察,并对肝脏进行了透射电镜观察.根据病变特点分为急性型和慢性型,以实质脏器出血或坏死,伴有心肌炎、脑膜炎和腱鞘炎为特征性病变.对屠宰患鸡肉尸提出了卫生评价.     

Peripheral blood lymphocyte subsets in fleece rot-resistant and -susceptible sheep

Objective To compare haematological values and lymphocyte phenotypes in the peripheral blood of fleece rot-resistant and -susceptible sheep.
Procedure Experiments were conducted on 2- and 3-year-old Merino rams, flock 1 (17 rams) and flock 2 (32 rams), respectively. Within each flock, individual rams were classified as fleece rot-resistant or -susceptible, based on established criteria. Total and differential white cell counts, and indirect fluorescent antibody tests specific for B cells and T cells were performed on all sheep. The concentration of various subsets of circulating lymphocytes was then determined in each sheep.
Results There were no significant differences between fleece rot-resistant and -susceptible sheep from either flock in the mean total or differential white cell counts. However, fleece rot-resistant rams in flock 1 did have a significantly higher concentration of circulating SBU-T1⁺ cells than fleece rot-susceptible rams from the same flock. No such difference was noted in the rams from flock 2. While all rams in flock 1 were free of clinical fleece rot, 24 rams in flock 2 (comprising all 17 fleece rot-susceptible and 7 of 15 fleece rot-resistant animals) had clinical signs of the disease. Fleece rot-free rams in this flock (irrespective of their classification as fleece rot-resistant or -susceptible) had significantly higher concentrations of circulating SBU-T1⁺ cells compared with fleece rot-affected animals. They also had significantly higher concentrations of circulating B cells, and total lymphocytes.
Conclusions An examination of peripheral blood lymphocyte subsets in fleece rot-resistant and -susceptible sheep revealed a possible association between resistance to fleece rot and the concentration of circulating SBU-T1⁺ cells.     

甲基对硫磷降解菌P-29的筛选及降解特性研究

采用富集培养法,从长期受农药污染的土壤中分离得到1株能高效降解甲基对硫磷的菌株P-29,经鉴定为铜绿假单胞菌(Pseudomonas aeruginosa)。该菌株以甲基对硫磷为唯一碳源时,30℃培养30h降解率达84.69%,其酶活性随培养时间的增加呈上升趋势。     

紫玉兰对铜绿微囊藻生长的抑制作用

[目的]探讨紫玉兰组织和器官对铜绿微囊藻生长的影响。[方法]在实验室条件下,以南太湖水华蓝藻铜绿微囊藻为材料,研究了不同处理方式的紫玉兰叶和花瓣对其生长的化感抑制作用。[结果]0.10%、0.50%和1.00%的紫玉兰叶提取液、高压灭菌紫玉兰叶和经过次氯酸钠消毒后的新鲜紫玉兰叶对铜绿微囊藻均有不同程度的抑制作用,0.10%紫玉兰花瓣提取液、0.10%高压灭菌紫玉兰花瓣和1.00%新鲜紫玉兰花瓣也可显著抑制铜绿微囊藻的生长。[结论]紫玉兰叶和花瓣中含有抑制铜绿微囊藻生长的化感物质,试验结果为生态控制蓝藻水华提供了理论依据。     

水貂绿脓杆菌分离株的血清型分析和Eric-PCR指纹图谱多样性研究

为了掌握山东地区水貂出血性肺炎流行情况,从2012年山东省内多个养貂社区进行水貂出血性肺炎流行病学调查。从病貂中分离获得48株绿脓杆菌,分别测定了分离株的生化特性、血清型以及部分菌株对小鼠与水貂的半数致死量（LD50）,同时运用Eric-PCR方法对分离进行了进行分型。结果显示,48株分离菌株与标准菌株生化特性基本一致,血清型G型为36株,血清型Ⅰ型为7株,血清型C型为4株;48株分离株大多数对恩诺沙星最敏感;动物试验显示,48株分离株对小鼠与水貂均能致病,所选4株分离株对小鼠与水貂的LD50有差异,且水貂对所选菌株显著敏感于小鼠;分子分型分为13个基因型。结果表明,该地区水貂出血性肺炎病原呈现遗传多样性。本试验为水貂出血性肺炎的防治提供了理论依据。     

血鹦鹉铜绿假单胞菌病原菌鉴定和药敏试验

对从患病血鹦鹉(Cichlasoma var.)肝、眼部脓肿处分离到2株细菌,对该分离菌进行人工感染实验、鉴定和药敏实验。结果显示:通过人工感染实验证明其对血鹦鹉有较强的致病性。分离菌革兰氏阴性杆状,氧化酶阳性、接触酶阳性、甲基红阴性,能够利用枸橼酸盐、丙二酸盐,发酵葡萄糖。综合分离菌的表型特征及分子生物学结果,鉴定分离菌为假单胞菌属(Pseudomonas)的铜绿假单胞菌(Pseudomonas aeruginosa)。药敏试验结果显示头孢哌酮、头孢他啶、壮观霉素、阿米卡星、阿奇霉素、氨噻酸单胺菌素和阿洛西林抑菌效果显著。     

小白菜联合铜绿假单胞菌对田间铅污染土壤的修复

针对土壤中铅(Pb)污染的生物修复,在种植小白菜的田间Pb处理土壤中,接种1株耐Pb铜绿假单胞菌(Pseudomonas aeruginosa)M2菌株,研究其对小白菜吸收Pb的影响。结果表明:接种M2可以降低土壤Pb污染对小白菜生长的抑制作用,促进小白菜对土壤Pb的吸收,使接种组小白菜生物量和株高分别增加7%和12%,根际土壤Pb残留量降低7%左右;接种处理的土壤脲酶和转化酶活性在小白菜整个生长期内均较未接种组高。结合前期盆栽试验结果得出,接种耐铅铜绿假单胞菌M2,可以促进小白菜对Pb污染土壤的修复。     

重组绿脓杆菌外毒素A受体结合区蛋白的初步复性及细胞生物学活性检测

用逐步稀释透析法将纯化的大肠杆菌表达的重组绿脓杆菌外毒素Ａ（ＰＥＡ）受体结合区蛋白初步复性,复性后的可溶性蛋白用于竞争抑制ＰＥＡ的细胞毒性实验。将１０μｇ／Ｌ的ＰＥＡ与其敏感细胞Ｌ９２９共孵育,３６ｈ左右可见细胞发生病变死亡,而同时加入复性的重组ＰＥＡ受体结合区蛋白的培养细胞孔与未加ＰＥＡ阴性对照培养细胞一样仍分裂增殖,这种ＰＥＡ细胞毒性抑制作用可持续到所有培养细胞老化死亡。结果表明,重组ＰＥＡ受体结合区蛋白可在体外竞争抑制ＰＥＡ对Ｌ９２９细胞的毒性。     

绿脓杆菌ATCC27853外毒素PE40基因的扩增与测序

目的 扩增绿脓杆菌ATCC27853外毒素基因PE40，并对PCR产物进行测序鉴定，为获得用于构建分子导向药物的毒素弹头基因PE40奠定基础。方法 采用PCR技术，以绿脓杆菌ATCC27853基因组DNA为模板，扩增PE40基因并测序。用DNASTAR软件将测得的序列与GenBank中的国际标准产毒株PA103的PE40基因序列进行比较。结果 扩增出目的基因片断，长度为1231bp。测序表明，ATCC27853与PA103核苷酸同源性为98%，产生了7个碱基的突变，突变碱基导致第364位的天冬酰胺变成丝氨酸，第506位的丝氨酸变成色氨酸，第515位的丝氨酸变成甘氨酸。但产生变化的3个氨基酸均不是文献报道中的重要活性位点。结论 产生变化的3个氨基酸不会对PEA的酶活性及细胞毒性产生很大影响，绿脓杆菌ATCC27853的PE40基因可用作分子导向药物的弹头。     

Seaweed Extracts: A Promising Source of Antibiofilm Agents with Distinct Mechanisms of Action against Pseudomonas aeruginosa

The organization of bacteria in biofilms is one of the adaptive resistance mechanisms providing increased protection against conventional treatments. Thus, the search for new antibiofilm agents for medical purposes, especially of natural origin, is currently the object of much attention. The objective of the study presented here was to explore the potential of extracts derived from three seaweeds: the green Ulva lactuca, the brown Stypocaulon scoparium, and the red Pterocladiella capillacea, in terms of their antibiofilm activity against P. aeruginosa. After preparation of extracts by successive maceration in various solvents, their antibiofilm activity was evaluated on biofilm formation and on mature biofilms. Their inhibition and eradication abilities were determined using two complementary methods: crystal violet staining and quantification of adherent bacteria. The effect of active extracts on biofilm morphology was also investigated by epifluorescence microscopy. Results revealed a promising antibiofilm activity of two extracts (cyclohexane and ethyl acetate) derived from the green alga by exhibiting a distinct mechanism of action, which was supported by microscopic analyses. The ethyl acetate extract was further explored for its interaction with tobramycin and colistin. Interestingly, this extract showed a promising synergistic effect with tobramycin. First analyses of the chemical composition of extracts by GC–MS allowed for the identification of several molecules. Their implication in the interesting antibiofilm activity is discussed. These findings suggest the ability of the green alga U. lactuca to offer a promising source of bioactive candidates that could have both a preventive and a curative effect in the treatment of biofilms.