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1.
c-di-GMP是细菌中广泛存在的第二信使,可通过效应蛋白参与调控细菌的生物被膜形成、运动性和毒力等生物学特性。YeaI因含有能结合c-di-GMP分子的EGEVF基序,可能作为c-di-GMP效应蛋白发挥作用。[目的] 研究yeaI基因缺失对奶牛源大肠杆菌临床分离株NJ17生物学特性的影响。[方法] 构建NJ17的yeaI缺失株(NJ17ΔyeaI)及回复株cNJ17ΔyeaI,分析yeaI对NJ17生物学特性(如生长特性、生物被膜形成能力和对小鼠乳腺上皮细胞(EpH4-Ev)的黏附)的影响。[结果] 成功构建NJ17的yeaI缺失株(NJ17ΔyeaI)及其回复株(cNJ17ΔyeaI);与野生株NJ17相比,缺失株NJ17ΔyeaI生长特性及耐药性无显著变化,生物被膜形成能力显著下降,运动性显著升高(P<0.05);透射电镜检测结果表明,yeaI缺失影响NJ17菌毛和鞭毛的形成;实时定量PCR(qPCR)结果显示,yeaI基因显著抑制NJ17鞭毛基因filGmotB的转录水平(P<0.05);血清杀菌实验表明,yeaI缺失能显著增强其抵抗血清杀菌作用(P<0.05);对EpH4-Ev细胞黏附实验表明,yeaI缺失对NJ17黏附性无显著影响(P>0.05)。[结论] yeaI对奶牛源大肠杆菌NJ17的生物学特性具有重要的调控作用。  相似文献   

2.
同甲壳素和壳聚糖这种生物大分子相比,壳寡糖具有许多独特的功能性质,如水溶性、保湿性、抗菌性、抗肿瘤和免疫促进性等。以数均分子量为5000的壳寡糖作为研究模型,根据凝胶电泳和紫外光谱分析,提出纳米级壳寡糖与pEGFPC-1质粒能通过静电结合或物理包裹形成复合物从而对DNA进行保护,同时证明形成壳寡糖/DNA复合物后,壳寡糖能够极大地提高DNA的贮存稳定性和结构稳定性;而DNaseI酶解实验也显示纳米级壳寡糖在合适比例下DNA有良好的保护作用,使其不被DNaseI降解,证明了纳米级壳寡糖应用于基因治疗载体的可行性与安全性。  相似文献   

3.
为探究林下参内生真菌球毛壳菌(Chaetomium globosum)FS-01菌株对人参病原菌的抑菌作用,该研究在实验室条件下,测定了FS-01菌株菌丝、发酵液和孢子悬浮液对人参黑斑病菌(Alternaria panax)、人参菌核病菌(Sclerotinia schinseng)、人参灰霉病菌(Botrytis cinerea)、人参立枯病菌(Rhizoctonia solani)、人参根腐病菌(Fusarium solani)5种人参病原菌的抑制作用。结果表明:内生真菌球毛壳菌FS-01对5种病原菌均有抑制作用,其中,对人参黑斑病菌的抑制作用最高,为30.80%,其次是人参立枯病菌、人参菌核病菌、人参根腐病菌和人参灰霉病菌; 发酵液抑菌实验结果表明,在加入内生真菌球毛壳菌FS-01菌株发酵液的PDA培养基上,对人参灰霉病菌的抑制作用最高,为82.09%,其次是人参菌核病菌、人参黑斑病菌、人参立枯病菌和人参根腐病菌; 孢子抑菌实验结果表明,在加入内生真菌球毛壳菌FS-01菌株孢子悬浮液的PDA培养基上,对人参黑斑病菌的抑制作用最高,为83.72%,其次是人参灰霉病菌、人参立枯病菌、人参菌核病菌和人参根腐病菌。综上结果认为,内生真菌球毛壳菌FS-01菌株对人参病原菌均有很高的抑菌作用,可作为人参病原菌的生防菌株资源。  相似文献   

4.
探究从油樟(Cinnamomum longipaniculatum)叶中提取出的不同极性黄酮样品对大肠杆菌(Escherichia coli)、志贺杆菌(Shigella)、金黄色葡萄球菌(Staphylococcus aureus)、稻瘟病菌(Magnaporthe grisea)和黄曲霉菌(Aspergillus flavus)五种病原菌的抑制作用。以五种病原菌为指示菌,将不同的黄酮样品滴加在滤纸片上,观察抑菌圈的大小。结果显示,样品Fr1、Fr2、Fr3、Fr4和Fr7对大肠杆菌有抑菌作用;样品Fr2、Fr3、Fr4、Fr5、Fr7和Fr8对志贺杆菌有抑菌作用;样品Fr4和Fr8对金黄色葡萄球菌有抑菌作用;样品过孔和Fr4对黄曲霉菌有抑菌作用;样品过孔对稻瘟病菌有抑菌作用。故不同极性的黄酮样品有良好的抑菌性。  相似文献   

5.
【目的】铜绿假单胞菌(Pseudomonas aerugionsa)二鸟苷酸环化酶SiaD调控着铜绿假单胞菌的生物被膜形成等表型。在研究过表达siaD对生物被膜的调控作用时发现,与野生型siaD基因回补菌株相比,一株回补菌株的生物被膜产量显著升高。本文的目的即是探究该菌株生物被膜产量升高的原因,并对该菌株的其他表型进行研究。【方法】通过测序确定突变位点;利用生物被膜定性和定量实验对发生点突变的菌株表型进行分析;利用Western blotting实验检测SiaDR119M蛋白表达水平;利用GST-pull down实验检测SiaC蛋白与SiaDR119M蛋白在体外的结合能力;针对siaDR119M点突变基因进行融合蛋白表达载体的构建,表达并纯化该蛋白,利用高效液相色谱检测SiaDR119M的酶活;为了进一步研究c-di-GMP与细菌运动能力的关系,对细菌的运动能力进行检测。【结果】测序比对结果显示,序列的第119个氨基酸发生了突变,由精氨酸突变成了甲硫氨酸。生物被膜定性和定量实验显示,与野生型siaD回补菌株相比,siaDR119M的回补菌株生物被膜产量增加,siaDR119A的回补菌株生物被膜产量低于siaDR119M的回补菌株,siaDR201A回补菌株生物被膜含量显著增加,siaDR119M R201A双突变回补菌株生物被膜的含量低于siaDR201A回补菌株。Western blotting和GST-pull down实验证明,与野生型SiaD蛋白相比,SiaDR119M蛋白表达水平无差别,SiaC和SiaDR119M蛋白之间存在特异的相互作用。高效液相色谱结果显示SiaDR119M蛋白酶活降低。运动能力检测实验中,与siaD野生型回补菌株相比,siaDR119M回补菌株运动能力减弱,siaDR201AsiaDR119M R201A回补菌株运动能力无差别。【结论】siaDR119M突变导致生物被膜合成增强,酶活降低,运动能力减弱。我们推测突变后表型的变化可能是因为突变在体内会影响SiaD蛋白与下游效应蛋白的相互作用,加强了下游效应蛋白的信号传导能力,然而具体机制有待进一步探索。  相似文献   

6.
从多糖提取后的紫皮石斛(Dendrobium devonianum Paxt.)渣上分离到一株能够水解石斛多糖的菌株,为丰富寡糖食品新原料种类,对该菌株的发酵产酶活性进行分析。利用酶法制备紫皮石斛寡糖,并进行小试和中试,采用硅胶柱色谱对寡糖进行初步分离,PMP衍生化后通过HPLC分析单糖组成。结果表明,水解石斛多糖的菌株为粗糙脉孢菌(Neurospora crassa)。该菌株液态发酵至第4天酶活最高,为0.1 U/μL,最佳酶解时间为24 h,粗酶液能够耐受30%的乙醇。通过粗酶液生物转化石斛多糖的小试和中试成功制备了大量的石斛寡糖,并对各组分进行了初步分离,单糖组成分析表明其主要由甘露糖组成,并含有少量的葡萄糖或果糖。通过粗糙脉孢菌酶法制备得到的紫皮石斛寡糖主要为甘露寡糖。  相似文献   

7.
捕食是影响牡蛎种群建立和牡蛎礁发育的重要生物因子之一。通过室内受控实验测定了日本蟳(Charybdis japonica)、脉红螺(Rapana venosa)和黄口荔枝螺(Thais luteostoma)对4组规格(W1:壳高10-20mm;W2:壳高20-30mm;W3:壳高30-40mm;W4:壳高>40mm)近江牡蛎(Crassostrea ariakensis)和熊本牡蛎(C.sikamea)的捕食偏好性和捕食效率。双因子方差分析结果表明,日本蟳对2种牡蛎的捕食效率没有显著性差异(P>0.05),但牡蛎规格大小显著影响着日本蟳的捕食效率(P<0.05),即日本蟳对W1组近江牡蛎的捕食效率显著高于W2和W4组(P<0.05),W3组的被捕食效率介于中间(P>0.05);日本蟳对W1组熊本牡蛎的捕食效率显著高于W2和W3组(P<0.05),W4组的被捕食效率与其他处理组均没有显著性差异(P>0.05)。牡蛎种类(P=0.590)和规格大小(P=0.357)对脉红螺的捕食效率均无显著性影响,不同规格的两种牡蛎均呈现较低的被捕食效率。黄口荔枝螺对2种牡蛎的捕食效率无显著性差异(P=0.917),但牡蛎规格大小显著影响其捕食效率(P=0.035),即对W1组熊本牡蛎捕食效率显著高于其他3个规格组(P<0.05),但其对不同规格近江牡蛎的捕食效率没有显著性差异(P>0.05)。2种牡蛎的壳厚与其壳高之间均存在极显著的正相关关系(P<0.001)。研究结果表明,3种无脊椎动物捕食者对近江牡蛎和熊本牡蛎并未表现出差异性的捕食偏好,但对不同规格牡蛎的捕食效率具有种间差异。  相似文献   

8.
本研究通过监测浙江健跳港牡蛎礁海域的牡蛎幼体补充量,并开展田间实验,比较了两种底物(牡蛎壳、岩石)的牡蛎附着效果,从而确定合理的牡蛎礁修复方式,推荐适宜的建礁材料。结果显示:牡蛎自然补充群体中共有4种牡蛎,即近江牡蛎(Crassostrea ariakensis)、熊本牡蛎(C. sikamea)、福建牡蛎(C. angulate)和猫爪牡蛎(Talonostrea talonata),补充量中以熊本牡蛎占绝对优势,相对丰度达95%以上。牡蛎补充量介于0~44 200 个/m2,月平均补充量为(7 165±1 246) 个/m2。附着底物筛选实验结果表明潮区(P<0.001)和底物类型(P=0.004)均显著影响牡蛎补充量,两因子之间存在显著的互作效应(F1,16=8.214,P=0.011)。4个实验组间附着牡蛎密度的排序为:高礁区岩石>高礁区牡蛎壳>低礁区岩石=低礁区牡蛎壳(P<0.05);相对于牡蛎壳,岩石是更为适宜的牡蛎附着底物。本研究得出浙江健跳港牡蛎礁为底物受限型,可在退化礁区投放岩石修复牡蛎礁。  相似文献   

9.
孙鹏  凌建忠  张辉  唐保军  姜亚洲 《生态学报》2021,41(3):1221-1228
选取象山港黑鲷个体为研究对象,以18S rDNA为靶标,利用Illumina Miseq高通量测序方法研究黑鲷饵料生物组成特征,分析不同龄组黑鲷的食性异同。通过序列比对,共在黑鲷胃含物中鉴定出41个属中的62种饵料生物,分属9个门,其中节肢动物门(Arthropoda)、绿藻门(Chlorophyta)和软体动物门(Mollusca)是黑鲷饵料生物的优势组成门类。从饵料生物相对丰度和出现频率上分析,石莼(Ulva lactuca)、熊本牡蛎(Crassostrea sikamea)、胸刺水蚤(Centropages hamatus)、日本蟳(Charybdis japonica)、毛蚶(Scapharca subcrenata)和褐菖鲉(Sebastiscus marmoratus)是黑鲷的优势饵料物种,所占饵料生物总相对丰度的比重达60.90%。相似性分析检验(ANOSIM)结果显示:1至4龄黑鲷个体的饵料生物组成不存在显著性差异。与传统食性分析方法相比,高通量测序法在黑鲷饵料生物检测灵敏性上显现了较为明显的优势,保障黑鲷等重要物种的种群稳定对于该海域具有重要的生态和经济意义。  相似文献   

10.
细菌生物被膜的形成是导致细菌耐药和引起持续性感染的主要原因之一。本文通过检测黄芩素对金黄色葡萄球菌26112菌株(Staphylococcus aureus 26112,SA26112)多糖细胞间黏附素(polysaccharide intercellular adhesion, PIA)的合成和胞外DNA(extracellular DNA,eDNA)释放量的影响,及其对icaA和cidA基因表达量的影响,探讨黄芩素对金黄色葡萄菌生物被膜形成的抑制作用及其机制。结果显示,黄芩素能抑制SA26112生物被膜的形成,其抑杀SA26112的最低抑菌浓度和最低杀菌浓度均为0.04 mg/mL。0.16 mg/mL黄芩素和256 μg/mL环丙沙星单独作用时,均不能杀死其成熟生物被膜内的SA26112细菌,而当二者联用时则可杀死成熟生物被膜内的细菌。黄芩素能显著抑制SA26112菌株PIA的合成、eDNA的释放量及icaA和cidA基因的相对表达量。其中,0.04 mg/mL黄芩素作用SA26112菌株24 h,与对照组相比,eDNA的释放量减少97%,icaA和cidA基因的相对表达量分别减少62%和41%。上述结果表明,黄芩素能抑制SA26112菌株生物被膜的形成,其作用机制可通过降低icaA和cidA的基因表达量,进而影响PIA的合成和eDNA的释放,来抑制金黄色葡萄球菌生物被膜的形成。  相似文献   

11.
Biofilms as complex microbial communities attached to surfaces pose several challenges in different sectors, ranging from food and healthcare to desalination and power generation. The biofilm mode of growth allows microorganisms to survive in hostile environments and biofilm cells exhibit distinct physiology and behaviour in comparison with their planktonic counterparts. They are ubiquitous, resilient and difficult to eradicate due to their resistant phenotype. Several chemical‐based cleaning and disinfection regimens are conventionally used against biofilm‐dwelling micro‐organisms in vitro. Although such approaches are generally considered to be effective, they may contribute to the dissemination of antimicrobial resistance and environmental pollution. Consequently, advanced green technologies for biofilm control are constantly emerging. Disinfection using nonthermal plasmas (NTPs) is one of the novel strategies having a great potential for control of biofilms of a broad spectrum of micro‐organisms. This review discusses several aspects related to the inactivation of biofilm‐associated bacteria and fungi by different types of NTPs under in vitro conditions. A brief introduction summarizes prevailing methods in biofilm inactivation, followed by introduction to gas discharge plasmas, active plasma species and their inactivating mechanism. Subsequently, significance and aspects of NTP inactivation of biofilm‐associated bacteria, especially those of medical importance, including opportunistic pathogens, oral pathogenic bacteria, foodborne pathogens and implant bacteria, are discussed. The remainder of the review discusses majorly about the synergistic effect of NTPs and their activity against biofilm‐associated fungi, especially Candida species.  相似文献   

12.
The viscoelastic properties of mono‐microbial biofilms produced by ocular and reference staphylococcal strains were investigated. The microorganisms were characterized for their haemolytic activity and agr typing and the biofilms, grown on stainless steel surface under static conditions, were analysed by Confocal Laser Scanning Microscopy. Static and dynamic rheometric tests were carried out to determine the steady‐flow viscosity and the elastic and viscous moduli. The analysed biofilms showed the typical time‐dependent behaviour of viscoelastic materials with considerable elasticity and mechanical stability except for Staphylococcus aureus ATCC 29213 biofilm which showed a very fragile structure. In particular, S. aureus 6ME biofilm was more compact than other staphylococcal biofilms studied with a yield stress ranging between 2 and 3 Pa. The data obtained in this work could represent a starting point for developing new therapeutic strategies against biofilm‐associated infections, such as improving the drug effect by associating an antimicrobial agent with a biofilm viscoelasticity modifier.  相似文献   

13.
China remains by far the largest aquaculture producer in the world. However, biofilms formed by pathogenic Vibrio strains pose serious problems to marine aquaculture. To provide a strategy for biofilm prevention, control, and eradication, extracts from 88 marine actinomycetes were screened. Thirty-five inhibited the biofilm formation of Vibrio harveyi, Vibrio vulnificus, and Vibrio anguillarum at a concentration of 2.5% (v/v). Thirty-three of the actinomycete extracts dispersed the mature biofilm. Six extracts inhibited the quorum-sensing system of V. harveyi by attenuating the signal molecules N-acylated homoserine lactones’ activity. Strain A66, which was identified as Steptomyces albus, both attenuated the biofilms and inhibited their quorum-sensing system. It is suggested that strain A66 is a promising candidate to be used in future marine aquaculture.  相似文献   

14.
This study quantifies the production of single and mixed biofilms of Candida albicans and Staphylococcus aureus to determine if such mixed biofilms have synergistic effects. Assays were performed using polystyrene microtitre plates of 96 wells, metabolic activity was measured by the enzymatic reduction of a tetrazolium salt (XTT) and colorimetric changes were measured at 490 nm. Confocal scanning laser microscopy was used to visualise the biofilms of each microorganism and its growth kinetics. The highest levels of biofilm formation were observed in mixed biofilms, followed by those of Candida albicans only, with the lowest levels of biofilm formation being detected for Staphylococcus aureus; all together these results suggest a synergistic relationship between the tested microorganisms.  相似文献   

15.
Recently it was demonstrated that for urinary tract infections species with a lower or unproven pathogenic potential, such as Delftia tsuruhatensis and Achromobacter xylosoxidans, might interact with conventional pathogenic agents such as Escherichia coli. Here, single- and dual-species biofilms of these microorganisms were characterized in terms of microbial composition over time, the average fitness of E. coli, the spatial organization and the biofilm antimicrobial profile. The results revealed a positive impact of these species on the fitness of E. coli and a greater tolerance to the antibiotic agents. In dual-species biofilms exposed to antibiotics, E. coli was able to dominate the microbial consortia in spite of being the most sensitive strain. This is the first study demonstrating the protective effect of less common species over E. coli under adverse conditions imposed by the use of antibiotic agents.  相似文献   

16.
Liu  Musang  Zheng  Hailin  Zeng  Rong  Liang  Guanzhao  Zheng  Nan  Liu  Weida 《Mycopathologia》2021,186(3):387-397

Aspergillus fumigatus (A. fumigatus) is the most common airborne opportunistic fungal pathogen. Biofilm formation is one of the main pathogenic mechanisms of A. fumigatus. During the past decades, A. fumigatus azole resistance has become prevalent due to the medical and agricultural use of antifungal drugs and fungicides. Until now, the role of fungal biofilms in azole resistance of A. fumigatus remains unclear. In the present study, we compared biofilm drug susceptibility and biofilm formation under itraconazole of azole-resistant strains, sensitive strains, and standard strains, separately. The biofilm viability and matrix thickness at the early and the late stage were measured by XTT assay and Calcofluor white. Our results showed that the sessile minimum inhibitory concentration of itraconazole, which describing the inhibition of drugs on fungi sessile with biofilm, was much higher than the traditional minimal inhibitory concentration of itraconazole. Additionally, low concentrations of itraconazole inhibited biofilm formation of A. fumigatus strains. Notably, biofilm formation by azole-resistant strains could not be inhibited by high concentrations of itraconazole but could be effectively restrained by low concentrations of micafungin, revealing the efficacy of a cell-wall inhibitor to disrupt A. fumigatus biofilm formation. However, late-stage biofilms of both azole-resistant strains and standard strains were hard to disrupt using itraconazole. We found that itraconazole was effective to prevent A. fumigatus biofilm formation at the early stage. For the treatment of A. fumigatus biofilm, our findings suggest that an early-stage preventive strategy is preferred and micafungin is effective to control the azole-resistant strain infection.

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17.
The discovery that biofilms are ubiquitous among the epiphytic microflora of leaves has prompted research about the impact of biofilms on the ecology of epiphytic microorganisms and on the efficiency of strategies to manage these populations for disease control and to ensure food safety. Biofilms are likely to influence the microenvironment and phenotype of the microorganisms they harbor. However, it is also important to determine whether there are differences in the types of bacteria within biofilms compared to those outside of biofilms so as to better target microorganisms via disease control strategies. Broad-leaved endive (Cichorium endivia var. latifolia) harbors biofilms containing fluorescent pseudomonads. These bacteria can cause considerable post-harvest losses when this plant is used for manufacturing minimally processed salads. To determine whether the population structure of the fluorescent pseudomonads in biofilms is different from that outside of biofilms on the same leaves, bacteria were isolated quantitatively from the biofilm and solitary components of the epiphytic population on leaves of field-grown broad-leaved endive. Population structure was determined in terms of taxonomic identities of the bacteria isolated, in terms of genotypic profiles, and in terms of phenotypic traits related to surface colonization and biofilm formation. The results illustrate that there are no systematic differences in the composition and structure of biofilm and solitary populations of fluorescent pseudomonads, in terms of either genotypic profiles or phenotypic profiles of the strains. However, Gram-positive bacteria tended to occur more frequently within biofilms than outside of biofilms. We suggest that leaf colonization by fluorescent pseudomonads involves a flux of cells between biofilm and solitary states. This would allow bacteria to exploit the advantages of these two types of existence; biofilms would favor resistance to stressful conditions, whereas solitary cells could foster spread of bacteria to newly colonizable sites on leaves as environmental conditions fluctuate.  相似文献   

18.

Background  

A biofilm is a complex community of microorganisms that develop on surfaces in diverse environments. The thickness of the biofilm plays a crucial role in the physiology of the immobilized bacteria. The most cariogenic bacteria, mutans streptococci, are common inhabitants of a dental biofilm community. In this study, DNA-microarray analysis was used to identify differentially expressed genes associated with the thickness of S. mutans biofilms.  相似文献   

19.
Legionella pneumophila, the aetiological agent of 90% of legionellosis cases, is a common inhabitant of natural and anthropogenic freshwater environments, where it resides in biofilms. Biofilms are defined as complex, natural assemblages of microorganisms that involve a multitude of trophic interactions. A thorough knowledge and understanding of Legionella ecology in relation to biofilm communities is of primary importance in the search for innovative and effective control strategies to prevent the occurrence of disease cases. This review provides a critical update on the state‐of‐the‐art progress in understanding the mechanisms and factors affecting the biofilm life cycle of L. pneumophila. Particular emphasis is given to discussing the different strategies this human pathogen uses to grow and retain itself in biofilm communities. Biofilms develop not only at solid‐water interfaces (substrate‐associated biofilms), but also at the water‐air interface (floating biofilms). Disturbance of the water surface can lead to liberation of aerosols derived from the floating biofilm into the atmosphere that allow transmission of biofilm‐associated pathogens over considerable distances. Recent data concerning the occurrence and replication of L. pneumophila in floating biofilms are also elaborated and discussed.  相似文献   

20.
面对日益严峻的能源紧缺与环境污染形势,电活性微生物(electroactive microorganisms)的电催化过程为实现绿色生产提供了新的思路。奥奈达希瓦氏菌具有独特的呼吸方式和电子传递能力,在微生物燃料电池、增值化学品的生物电合成、金属废物处理和环境修复系统等领域有着广泛的应用。奥奈达希瓦氏菌(Shewanella oneidensis MR-1)电活性生物被膜是实现电活性微生物电子传递过程的优良载体,其形成过程十分复杂且受到多种因素的影响和调控,在增强细菌环境抗逆性、提高电子传递效率等多方面发挥着十分重要的作用。本文较为系统地综述了奥奈达希瓦氏菌生物被膜的形成过程、影响因素及其在生物能源、生物修复和生物传感中的相关应用,为进一步实现其在更多领域的应用提供了理论基础。  相似文献   

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