牛乳源大肠杆菌生物被膜形成及抗生素的作用

为研究大肠杆菌生物被膜(Biofilms,BF)对耐药性的影响及抗生素对BF形成的作用,以陕西关中地区乳房炎奶牛的乳样中分离的35株大肠杆菌为研究对象,通过刚果红琼脂和结晶紫染色法测定菌体形成BF的能力;通过药物敏感性试验检测BF形成前后菌体耐药性的变化;用结晶紫染色法结合荧光显微镜观察不同质量浓度抗生素对BF的影响。结果显示,35株大肠杆菌中有19株(54.29%)为BF阳性,以形成强、中膜能力为主(84.21%);大肠杆菌形成BF后使头孢噻呋、链霉素、四环素、环丙沙星、庆大霉素、青霉素的最小抑菌质量浓度及最小杀菌质量浓度分别提高4～16倍和8～64倍;抗生素对BF形成的抑制和清除作用随着药物质量浓度增大而加强,其中环丙沙星、头孢噻呋的效果较好。     

维生素B7和B12对细菌生物被膜形成及厚壳贻贝幼虫变态的影响

为探究B族维生素对海洋细菌生物被膜形成、海洋贝类幼虫变态所产生的作用,本研究首先使用维生素B7 (VB7)和B12 (VB12)直接刺激厚壳贻贝(Mytilus coruscus)幼虫,观察其对变态的直接诱导活性;然后通过添加VB7和VB12,与海假交替单胞菌(Pseudoalteromonas marina)共同形成生物被膜,分析B族维生素对生物被膜形成及其生物学特性的影响;同时检测生物被膜变化对厚壳贻贝幼虫变态发育的影响。研究结果显示,0.02 mmol/L浓度VB7和VB12可以直接诱导厚壳贻贝幼虫的变态,且效果最为显著(P<0.05);0.02 mmol/L浓度VB7和VB12处理后的海假交替单胞菌生物被膜对幼虫附着变态的诱导作用均显著提高(P<0.05);进一步通过细菌密度计数、膜厚度分析、可拉酸染色和定量等方法,揭示VB7和VB12处理后生物被膜细菌密度、膜厚度以及胞外多糖、蛋白和脂质均显著增加(P<0.05)。研究结果证实,VB7和VB12可能通过改变海洋细菌生物被膜的生物学特性,进而调控厚壳贻贝幼虫变态发育。本研究为探究厚壳贻贝幼虫附着变态的分子机制提供了新的理论依据和创新思路,同时为B族维生素在提高厚壳贻贝人工育苗技术、改善厚壳贻贝养殖产业问题和促进海洋牧场生态修复建设等方面的应用提供了理论基础。     

Immune surveillance mechanisms of the skin against the stealth infection strategy of Pseudomonas aeruginosa—Review

The present review aims to provide insight into the complex interactions between the host and Pseudomonas aeruginosa—an opportunistic microbial agent causing skin infections. Heat, humidity and skin pH are among the factors beneficial for the development of this Gram-negative agent. To cause infection, Pseudomonas aeruginosa should first overcome the primary mechanisms of defense including the cell elements and humoral factors of the skin, as well as non-specific responses—phagocytosis, inflammation, acute phase response. All they are analysed with emphasis on the fact that their detailed understanding would help revealing their potential and allow for their efficient control.     

Bacterial flora on Cascades frogs in the Klamath mountains of California

Amphibians are experiencing global declines due in part to the infectious disease chytridiomycosis. Some symbiotic bacteria residents on frog skin have been shown to inhibit the growth of Batrachochytrium dendrobatitis (Bd) but few studies have attempted to fully describe the resident bacterial flora of frog skin. We cultured and sequenced 130 bacterial isolates from frogs collected from the California Klamath Range, recovering predominantly Gram-negative bacteria from 20 higher order taxa and 31 genera. There were also a large number of unclassifiable isolates. Forty-three isolates were assessed for their ability to inhibit the growth of Bd in vitro; of these, two had strong and three had slight anti-Bd activity. We suggest that many bacterial species may play a secondary role in Bd resistance, acting synergistically with inhibitory species. Future research is required in order to characterize these interactions. Understanding the relationships between bacterial strains may be important in predicting and managing the effects of future anti-Bd treatments such as antimicrobial compounds or probiotic bacteria.     

感潮河道生物膜吸附重金属性能及迁移规律研究

[目的]研究感潮河道生物膜对重金属的吸附性能及迁移规律。[方法]利用ICP-AES法,测定了感潮河道生物膜（自然和人工培养）及其附近河道底泥（表层沉积物）和水体中的重金属（Mn、Zn、Cu、Pb、Ni、Cd）含量,研究了感潮河道生物膜对重金属的吸附性能,并进一步探究重金属在生物膜和河道底泥中的迁移规律。[结果]在感潮河道环境下,重金属在生物膜中和底泥中的含量水平基本相当;生物膜对重金属的吸附有一定的局限性,其吸附性能受多种因素的影响,如生物膜特性、重金属种类和存在形态、底泥中重金属含量、河道水文条件及地质形态、生物膜的成膜时间等;重金属通过水体在生物膜和底泥间迁移,最终达到动态平衡,表现出一定的规律性。[结论]该研究为今后利用生物膜法修复感潮河道重金属污染提供了依据。     

循环水养鳗系统生物过滤器中微生物群落的代谢特性

为了研究鳗鱼循环水养殖系统不同水处理单元的微生物群落碳代谢特征,实验采用Biolog Eco技术,分析了流化床两个槽和滴流式生物过滤器上、中、下三层的生物膜微生物群落功能多样性。结果显示,流化床两个槽和滴流式生物过滤器中、下层微生物多样性指数（Shannon-Wiener指数、Simpson指数和Pielou指数）无显著差异（P>0.05）,但均显著高于滴流式生物过滤器上层（P<0.05）。平均色度变化（AWCD）与主成分分析（PCA）均证明滴流式生物过滤器上层与其它采样点微生物代谢差异较大。各采样点微生物未对ECO板某一大类碳源表现出偏好,但对衣康酸、D-半乳糖醛酸、L-精氨酸、L-天门冬酰胺、L-丝氨酸、D-甘露醇、D-木糖、N-乙酰-D-葡萄糖氨、吐温40、吐温80、苯乙胺等单一碳源利用较好;而对γ-羟丁酸和α-丁酮酸以及D,L-α-磷酸甘油和1-磷酸葡萄糖利用较差。某些碳源种类如D-葡糖胺酸、α-D-乳糖、2-羟基苯甲酸仅能被部分采样点的微生物利用。本实验利用Biolog EcoPlateTM技术研究中试规模循环水处理单元微生物群落代谢特征,研究结果为生物过滤器的调控提供了一种新的思路即可以通过碳源调节,来促进生物膜微生物群落结构的改变以此提高水处理效率。     

悬浮式活性炭纤维帘生物膜净化水源水氮污染研究

利用自制的悬浮式活性炭纤维帘生物膜反应器处理模拟的氮污染水源水,考察了载体上生物膜驯化过程中生物相的变化和反应器内基质浓度的降解情况.试验结果表明,当进水中CODCr、NH3-N和TN的浓度分别达到37.1、1.79和2.04 sg/L时,出水中的浓度分别为15.3、0.39和0.48 mg/L,基本达到《地表水环境质量标准》（GB2002-3838）的Ⅱ类水质要求,去除率分别达到58.7％、78.4％和76.2％.与仅靠悬浮式活性炭纤维帘反应器吸附降解的去除率相比较,悬浮式活性炭纤维帘生物膜反应器的去除效果有明显提高.     

Influence of selected bactericides on biofilm formation and viability of Xanthomonas citri subsp. citri

Citrus Bacterial Canker (CBC) is a serious disease that affects production of almost all commercial citrus cultivars in subtropical citrus growing regions worldwide. The causal agent, Xanthomonas citri subsp. citri (Xcc), is classified as a quarantine pathogen in European Union (EU) which necessitates treatment of citrus fruit before entry into the EU marketing zone. In this study, the effectiveness of selected bactericides for leaf and fruit disinfection was evaluated. Bacterial aggregation and viability were assayed on abiotic or biotic surfaces in vitro and in planta after treatments with NaCl, CuSO₄, NaClO, sodium orthophenylphenate and two hydrogen peroxide based compounds. Most of the bactericides at higher concentrations reduced biofilm formation and Xcc viability compared to the non-treated control, but did not completely prevent or remove biofilms or eradicate Xcc from either biotic or abiotic surfaces. Some of the bactericides at sub-lethal concentrations increased aggregates in which Xcc was viable. Based on these results, we conclude that exposure to the bactericides is variable depending on biofilm formation and that plant and fruit disinfection will not only require treatment with an effective bactericide to kill the bacterium but also include the biofilm disruption.     

不同理化因素对乳房链球菌生物膜形成的影响

采用微量板半定量法,研究影响新疆南疆地区奶牛乳房炎性乳房链球菌生物膜形成的因素,探索不同理化因素对乳房链球菌生物膜形成的影响。结果表明,在THY(Todd Hewitt Broth+0.1%Yeast Extract)培养基中加入w=0.5%的牛奶能促进乳房链球菌的生长及生物膜的形成;检测的3种培养基中,BHI培养基最有利于乳房链球菌的生长及生物膜的形成;不同培养时间结果显示,36h培养更有利于乳房链球菌的生长及生物膜的形成;不同pH的试验结果表明,pH等于7时最有利于乳房链球菌的生长及生物膜的形成。     

Development of a molecular diagnostic test applied to experimental abattoir surveillance on bovine tuberculosis

Biofilm formation where bacterial cells adhere to a surface and surround themselves in a polysaccharide matrix is thought to be an important factor in disease initiation and persistence for many bacterial species. We have examined biofilm formation by Mycoplasma mycoides subsp. mycoides small colony using a simple model without an air/liquid interface and have found that adherent Mmm SC was more resistant to many stresses, including heat, osmotic shock and oxidative stress. Biofilms of Mmm SC also exhibited remarkable persistence and were able to survive for up to 20 weeks in stationary phase. Significant variation was seen between Mmm SC strains in their ability to form a biofilm and the morphology of the biofilm produced with some strains unable to produce microcolonies. Proteomic analysis found that a number of proteins linked to adherence were over-expressed in biofilms compared with planktonic cells.