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1.
周正虎  王传宽 《植物生态学报》2016,40(12):1257-1266
土壤碳(C)、氮(N)、磷(P)化学计量特征会显著影响微生物的生长、群落结构、生物量C:N:P化学计量及其代谢活动。然而生态系统演替过程中土壤-微生物C:N:P化学计量的时间格局及其协调关系还不明确。为此, 该研究收集了2016年5月以前发表的文献中19个生态系统演替序列(包括13个森林、6个草地生态系统)的土壤-微生物生物量C:N:P研究结果, 整合分析了其中土壤-微生物生态化学计量的时间动态, 结果表明: (1)生态系统演替过程中土壤C:N没有一致的时间格局, 而土壤C:P和N:P均随演替进程显著增加, 其中土壤C:N:P与演替时间之间线性关系的斜率与相应演替序列的初始土壤有机C含量呈负相关关系。(2)演替进程中土壤-微生物生物量C:N:P没有一致的时间格局。(3)微生物生物量C占土壤有机C百分比(qMBC)、微生物生物量N占土壤全N百分比、微生物生物量P占土壤全P百分比均随着演替进程而显著增加, 即单位资源所能支持的微生物生物量随着演替进程而增加, 这与宏观生态系统演替理论相符。(4) qMBC随着土壤C:N、C:P和N:P以及C:N、C:P和N:P化学计量不平衡性(即土壤C:N、C:P和N:P分别除以微生物生物量C:N、C:P和N:P)的增加而减小; 其中, C:N、C:P和N:P化学计量不平衡性解释了qMBC变异性的37%-57%, 是演替时间解释率的7-17倍, 表明土壤-微生物生态化学计量关系对qMBC演替动态有重要影响。该研究强调了生态化学计量学理论和生态系统演替理论在土壤微生物时间动态研究中的重要作用, 表明适当地融合生态学宏观理论于土壤微生物研究可以加深对土壤-微生物生态过程的认识。  相似文献   

2.
葡萄球菌核酸酶是金黄色葡萄球菌(Staphylococcusaureus)的一个重要毒力因子,它的生物学作用仍没有完全阐述清楚.本研究观察到金黄色葡萄球菌核酸酶产生菌株的生物被膜形成受到明显抑制.葡萄球菌核酸酶是由nucl基因编码,当nucl基因被敲除后,突变菌株生物被膜形成能力大大增加.扫描电子显微镜和激光共聚焦显微镜用于评价nucl基因在生物被膜形成中的作用.另外,nucl基因编码的产物——葡萄球菌核酸酶和NUCl重组蛋白对其他生物被膜形成细菌(铜绿假单胞菌(Pseudomonas aeruginosa)、猪胸膜肺炎放线杆菌(Actinobacillus pleuropneumoniae)和副猪嗜血杆菌(Haemophilus parasuis))同样有明显抑制作用.本研究表明,葡萄球菌核酸酶和生物被膜的形成之间有直接联系,并且葡萄球菌核酸酶起着抑制生物被膜形成的重要作用,为研究葡萄球菌核酸酶的生物学作用和理解葡萄球菌核酸酶抑制生物被膜形成提供理论依据.  相似文献   

3.
苦参碱对表皮葡萄球菌生物被膜作用初探   总被引:2,自引:0,他引:2  
通过中药有效成分苦参碱对表皮葡萄球菌生物被膜抑制作用的研究,为表皮葡萄球菌生物被膜引起的相关感染提供新的治疗途径。利用XTT减低法评价苦参碱对表皮葡萄球菌初始粘附及生物被膜内细菌代谢的影响,镜下观察该药对表皮葡萄球菌生物被膜的形态学影响。结果表明:苦参碱对表皮葡萄球菌生物被膜菌的SMIC50和SMIC80分别为62.5 mg/L和500 mg/L;1 000 mg/L浓度的苦参碱对表皮葡萄球菌早期粘附有抑制作用;250 mg/L浓度的苦参碱对表皮葡萄球菌生物被膜的形态有显著影响。因此可见,苦参碱对表皮葡萄球菌生物被膜的形成与粘附均有抑制作用。  相似文献   

4.
抗菌肽17BIPHE2对金黄色葡萄球菌生物被膜的抑制作用   总被引:2,自引:0,他引:2  
【目的】研究抗菌肽17BIPHE2单独使用及联合抗生素对金黄色葡萄球菌(Staphylococcus aureus)生物被膜的抑制作用。【方法】采用刚果红平板测试法和结晶紫染色评估受试菌形成生物被膜的能力;微量肉汤稀释法和琼脂平板测试法测定金黄色葡萄球菌最小抑菌浓度(MIC)和最小杀菌浓度(MBC);利用抑制金黄色葡萄球菌黏附实验和生物被膜形成抑制实验观察17BIPHE2单独使用及联合抗生素对生物被膜黏附阶段和形成阶段的影响;通过扫描电子显微镜(SEM)观察17BIPHE2单独使用及联合抗生素对成熟生物被膜的清除作用。【结果】17BIPHE2的MIC为8μmol/L,1/2×MIC就可以有效抑制浮游菌的生长。单独使用17BIPHE2在细菌黏附阶段抑制率为40%,在生物被膜形成阶段抑制率达到35%。17BIPHE2联合抗生素使用较单独使用抗生素其抑制率均有所下降。生物被膜成熟阶段17BIPHE2于1/4×MIC浓度即可促进生物被膜崩解,1×MIC生物被膜崩解同时细菌黏附量有所下降,联合万古霉素促进生物被膜崩解同时细菌胞质大量外泄。【结论】抗菌肽17BIPHE2具有良好的抑制金黄色葡萄球菌生物被膜作用,联合抗生素其抗生物被膜作用进一步提高。这将为治疗由金黄色葡萄球菌生物被膜引起的相关感染提供了一个新思路。  相似文献   

5.
乔瑞红  谢鲲鹏  谢明杰 《微生物学报》2015,55(10):1238-1244
摘要:细菌的耐药性问题是目前医学临床面临的严峻问题,其中细菌生物被膜的形成是引起细菌持续性感染的主要致病机制之一。细菌生物被膜的形成过程十分复杂,受多种因子和多基因的共同调控,且不同的因子和基因在生物被膜形成的不同阶段所起的作用不同。本文重点对引起院内感染的主要致病菌葡萄球菌的生物被膜形成的基因调控机制,以及药物抑制葡萄球菌生物被膜的研究现状进行综述,旨在为解决医学临床中存在的细菌感染,研制抗生物被膜药物和疫苗等提供参考。  相似文献   

6.
【背景】随着医用内置物的广泛使用,由表皮葡萄球菌生物被膜导致的医院获得性感染不断增多,目前鲜见关于表面活性剂针对表皮葡萄球菌生物被膜作用的报道。【目的】通过研究阴离子型表面活性剂十二烷基苯磺酸钠(sodium dodecyl benzene sulfonate,SDBS)分别对ATCC 35984 (产膜表皮葡萄球菌标准株)生物被膜的清除、生物被膜内细菌代谢和形成生物被膜的关键物质多糖胞间黏附素(polysaccharide intercellular adhesion,PIA)产生的影响,为临床使用SDBS防治由表皮葡萄球菌生物被膜引起的相关感染提供可靠的理论及实践依据。【方法】利用XTT减低法,评价SDBS对ATCC 35984已形成生物被膜的清除效率及对生物被膜内细菌代谢的影响;激光共聚焦显微镜观察SDBS对生物被膜作用的效果;采用刚果红培养基观察SDBS对PIA产生的影响。【结果】浓度为256、128、64、32、16 mg/L的SDBS在作用6、12、24 h时,对ATCC 35984的生物被膜均有显著的清除效率(P0.01);浓度为32 mg/L时对生物被膜内细菌的代谢有显著抑制作用(P0.05),并随作用浓度的增加而增强;激光共聚焦显微镜观察显示256、128、64 mg/L的SDBS对生物被膜的清除效率较为理想,SDBS浓度为64、32 mg/L时对PIA的形成无明显抑制作用。【结论】SDBS对表皮葡萄球菌生物被膜内细菌的代谢有显著抑制作用,对生物被膜形态结构有显著破坏作用。  相似文献   

7.
目的研究桑螵蛸挥发油提取物对金黄色葡萄球菌生物被膜形成的体外抑制效应。方法采用六孔板为载体培养细菌生物被膜,在刚果红平板鉴定使用的金黄色葡萄球菌菌株为生物被膜阳性菌株的基础上,再采用银染后通过倒置显微镜观察法来观察桑螵蛸挥发油提取物及其他药物对金黄色葡萄球菌生物被膜形成的体外抑制效应。结果空白对照组细菌生物被膜明显,药物实验组细菌生物被膜受到抑制,且桑螵蛸挥发油实验组抑制效果最明显。结论桑螵蛸挥发油提取物对金黄色葡萄球菌生物被膜的形成有明显的抑制效应,为下一步研究其详细有效成分及开发提供基础数据和理论依据。  相似文献   

8.
目的研究桑螵蛸挥发油提取物对金黄色葡萄球菌生物被膜形成的体外抑制效应。方法采用六孔板为载体培养细菌生物被膜,在刚果红平板鉴定使用的金黄色葡萄球菌菌株为生物被膜阳性菌株的基础上,再采用银染后通过倒置显微镜观察法来观察桑螵蛸挥发油提取物及其他药物对金黄色葡萄球菌生物被膜形成的体外抑制效应。结果空白对照组细菌生物被膜明显,药物实验组细菌生物被膜受到抑制,且桑螵蛸挥发油实验组抑制效果最明显。结论桑螵蛸挥发油提取物对金黄色葡萄球菌生物被膜的形成有明显的抑制效应,为下一步研究其详细有效成分及开发提供基础数据和理论依据。  相似文献   

9.
香芹酚抑制金黄色葡萄球菌生物被膜的形成   总被引:1,自引:0,他引:1  
【背景】生物被膜是细菌的一种自我保护形式,可以增强细菌对药物及宿主免疫应答的抵抗力,引起细菌耐药性和持续性感染。【目的】探究香芹酚对金黄色葡萄球菌生物被膜的作用机制,为开发新型抗生物被膜药物提供可靠的理论依据。【方法】通过结晶紫染色法检测香芹酚对供试菌株生物被膜形成的抑制和对成熟生物被膜的清除作用;使用刚果红平板法探究香芹酚对供试菌株生物被膜形成过程中细胞间多糖黏附素(polysaccharide intercellular adhesion,PIA)合成的作用;通过分光光度法检测香芹酚对胞外DNA (extracellular DNA,eDNA)分泌的抑制作用;利用RT-PCR技术检测香芹酚对供试菌株的生物被膜相关基因icaA、cidA和sarA转录水平的影响。【结果】香芹酚对生物被膜形成的抑制和生物被膜的清除均有较强作用效果。256μg/mL香芹酚抑制PIA合成和e DNA释放的效果显著。香芹酚可通过抑制相关基因转录从而抑制生物被膜的形成,当64μg/mL的香芹酚作用后,sarA的转录水平降低了60.44%±2.91%,cidA的转录水平降低了76.48%±1.67%,icaA的转录水平降低了70.00%±1.94%。【结论】香芹酚对金黄色葡萄球菌ATCC 25923生物被膜的抑制和清除作用显著,其作用机制主要是通过降低icaA、sarA和cidA基因转录水平抑制PIA的合成和eDNA的释放。  相似文献   

10.
建立体外铜绿假单胞菌生物膜(biofilm BF)模型,探讨青蒿琥酯(artesunate)对生物膜的影响。分光光度法测定青蒿琥酯对铜绿假单胞菌浮游菌生长的影响。选取铜绿假单胞菌野生株(PAO1)建立生物膜模型,设立对照组、青蒿琥酯组、环丙沙星(ciprofloxacin)组。结晶紫染色后测定570 nm波长光密度值,以观察6 h时细菌粘附情况;建模3 d后经不同浓度的青蒿琥酯或环丙沙星处理后利用平板稀释计数法计算活菌数;利用激光扫描共聚焦显微镜成像技术(confocal laser scanning microscopy,CLSM)结合生物膜定量分析软件COMSTAT对生物膜的单位面积生物量、平均厚度、粗糙系数、平均扩散距离进行定量分析。研究显示青蒿琥酯对铜绿假单胞菌浮游菌无明显抑制作用。建模3 d后,生物膜经不同浓度的青蒿琥酯干预12 h后,512μg/m L、1 024μg/m L组生物膜内的活菌数分别为(6.99±0.21)、(6.45±0.19)log10 CFU/m L,与对照组相比,差异有统计学意义(p0.05)。青蒿琥酯组(512μg/m L)和环丙沙星组在6 h时细菌粘附性显著下降,与对照组相比有统计学差异(p0.05)。与对照组相比,经青蒿琥酯和环丙沙星处理后生物膜生物量、平均厚度以及平均扩散距离等结构指标数值都有明显减少(p0.05);青蒿琥酯组粗糙系数增加(p0.05),环丙沙星组粗糙系数无明显变化(p0.05),但这两组的粗糙系数对比有统计学差异(p0.05)。该研究表明青蒿琥酯能够降低铜绿假单胞菌粘附性及破坏成熟生物膜结构。  相似文献   

11.
In the environment, multiple microorganisms coexist as communities, competing for resources and often associated as biofilms. In this study, single- and dual-species biofilm formation by, and specific activities of, six heterotrophic intergeneric bacteria were determined using 96-well polystyrene plates over a 72-h period. These bacteria were isolated from drinking water and identified by partial 16S rRNA gene sequencing. A series of planktonic studies was also performed, assessing the bacterial growth rate, motility, and production of quorum-sensing inhibitors (QSI). This constituted an attempt to identify key attributes allowing bacteria to effectively interact and coexist in a drinking-water environment. We observed that in both pure and dual cultures, all of the isolates formed stable biofilms within 72 h, with specific metabolic activity decreasing, in most cases, with an increase in biofilm mass. The largest single- and dual-biofilm amounts were found for Methylobacterium sp. and the combination of Methylobacterium sp. and Mycobacterium mucogenicum, respectively. Evidences of microbial interactions in dual-biofilm formation, associated with appreciable biomass variation in comparison with single biofilms, were found for the following cases: synergy/cooperation between Sphingomonas capsulata and Burkholderia cepacia, S. capsulata and Staphylococcus sp., and B. cepacia and Acinetobacter calcoaceticus and antagonism between S. capsulata and M. mucogenicum, S. capsulata and A. calcoaceticus, and M. mucogenicum and Staphylococcus sp. A neutral interaction was found for Methylobacterium sp.-M. mucogenicum, S. capsulata-Staphylococcus sp., M. mucogenicum-A. calcoaceticus, and Methylobacterium sp.-A. calcoaceticus biofilms, since the resultant dual biofilms had a mass and specific metabolic activity similar to the average for each single biofilm. B. cepacia had the highest growth rate and motility and produced QSI. Other bacteria producing QSI were Methylobacterium sp., S. capsulata, and Staphylococcus sp. However, only for S. capsulata-M. mucogenicum, S. capsulata-A. calcoaceticus, and M. mucogenicum-Staphylococcus sp., dual-biofilm formation seems to be regulated by the QSI produced by S. capsulata and Staphylococcus sp. and by the increased growth rate of S. capsulata. The parameters assessed by planktonic studies did not allow prediction and generalization of the exact mechanism regulating dual-species biofilm formation between the drinking-water bacteria.  相似文献   

12.
Nontypeable Haemophilus influenzae (NTHI) causes chronic infections that feature the formation of biofilm communities. NTHI variants within biofilms have on their surfaces lipooligosaccharides containing sialic acid (NeuAc) and phosphorylcholine (PCho). Our work showed that NeuAc promotes biofilm formation, but we observed no defect in the initial stages of biofilm formation for mutants lacking PCho. In this study, we asked if alterations in NTHI PCho content affect later stages of biofilm maturation. Biofilm communities were compared for NTHI 2019 and isogenic mutants that either lacked PCho (NTHI 2019 licD) or were constitutively locked in the PCho-positive phase (NTHI 2019 licON). Transformants expressing green fluorescent protein were cultured in continuous-flow biofilms and analyzed by confocal laser scanning microscopy. COMSTAT was used to quantify different biofilm parameters. PCho expression correlated significantly with increased biofilm thickness, surface coverage, and total biomass, as well as with a decrease in biofilm roughness. Comparable results were obtained by scanning electron microscopy. Analysis of thin sections of biofilms by transmission electron microscopy revealed shedding of outer membrane vesicles by NTHI bacteria within biofilms and staining of matrix material with ruthenium red in biofilms formed by NTHI 2019 licON. The biofilms of all three strains were comparable in viability, the presence of extracellular DNA, and the presence of sialylated moieties on or between bacteria. In vivo infection studies using the chinchilla model of otitis media showed a direct correlation between PCho expression and biofilm formation within the middle-ear chamber and an inverse relationship between PCho and persistence in the planktonic phase in middle-ear effusions. Collectively, these data show that PCho correlates with, and may promote, the maturation of NTHI biofilms. Further, this structure may be disadvantageous in the planktonic phase.  相似文献   

13.
近年来,微塑料引起的环境污染已经成为一个全球性的问题,在海洋环境中,微生物可以附着于微塑料表面形成生物被膜。已有研究表明生物被膜可以为生活在其内部的细菌提供保护,被膜中可能富集了对人体或者水生生物有害的致病菌,且频繁的基因交流可能产生更多耐药菌。微塑料表面附着的微生物,能借助大洋环流随微塑料在海洋中迁徙,进而可能引起微生物入侵事件的发生。主要对微塑料与生物被膜之间的相互作用、微塑料与附着在其表面的塑料降解菌、微塑料与致病菌、微塑料对微生物迁徙的影响,以及微塑料表面生物被膜中耐药基因的扩散进行综述,对微塑料附着微生物未来研究方向进行了展望,为更好地了解海洋微塑料污染提供参考。  相似文献   

14.
The effect of Dexiostoma (filter feeder), Vannella, Chilodonella (raptorial feeders), Spumella , and Neobodo (direct interception feeders) on the morphology of multispecies bacterial biofilms was investigated in small flow cells. The filter feeder Dexiostoma campylum did not alter biofilm volume and porosity but stimulated the formation of larger microcolonies compared with ungrazed biofilms. In contrast, the raptorial feeder Vannella sp. efficiently grazed bacteria from the biofilm surface, leading to smaller microcolonies and lower maximal and basal layer thickness compared with ungrazed biofilms. Microcolony formation was not stimulated in the presence of the sessile Spumella sp. Chilodonella uncinata rasped bacteria from the outer surface leading to mushroom-shaped microcolonies. In the presence of C. uncinata and Spumella sp., the biofilm volume was 2.5–6.3 times lower compared with ungrazed biofilms. However, the biofilm porosity and the ratio of biofilm surface area to biofilm volume were 1.5–3.7 and 1.2–1.8 times higher, respectively. Thus, exchange of nutrients and gases between the biofilm and its surrounding fluid should also be improved in deeper biofilm layers, hence accelerating microbial growth.  相似文献   

15.
The pH-value played a crucial role for the development and current production of anodic microbial electroactive biofilms. It was demonstrated that only a narrow pH-window, ranging from pH 6 to 9, was suitable for growth and operation of biofilms derived from pH-neutral wastewater. Any stronger deviation from pH neutral conditions led to a substantial decrease in the biofilm performance. Thus, average current densities of 151, 821 and 730 μA cm(-2) were measured for anode biofilms grown and operated at pH 6, 7 and 9 respectively. The microbial diversity of the anode chamber community during the biofilm selection process was studied using the low cost method flow-cytometry. Thereby, it was demonstrated that the pH value as well as the microbial inocula had an impact on the resulting anode community structure. As shown by cyclic voltammetry the electron transfer thermodynamics of the biofilms was strongly depending on the solution's pH-value.  相似文献   

16.
牙菌斑生物膜是附着于牙釉质表面,由复杂的微生物群落构成的一种聚集体。牙菌斑生物膜的形成与生长对口腔健康有着直接或间接的影响,许多研究证实口腔疾病如龋齿和牙周病都与细菌的积累及牙菌斑的形成有关。在牙菌斑生物膜形态建成过程中,牙齿表面最初的定殖菌对生物膜的微生物组成和结构至关重要,这些初级定殖菌决定了后续与之结合形成共生体的微生物种类和数量。不同的微生物组成可能在与生物膜形成相关的口腔病理状况中发挥不同的作用。因此,本文就牙菌斑生物膜的生长及控制进行综述,介绍其微生物的早期定殖和成熟过程、以及通过物理和化学方法对牙菌斑生物膜的控制,以期为了解牙菌斑生物膜的形成机制及相关口腔疾病的预防和治疗提供有价值的参考。  相似文献   

17.
This study reports the influence of Mg ions on the development and architecture of biofilms by a chromium resistant and reducing bacterium Arthrobacter sp. SUK 1201 and their utilization in the removal of toxic hexavalent chromium. Among the different metal ions tested, Mg(II) greatly influenced the biofilm growth in peptone yeast extract glucose medium. Both Scanning and Confocal Laser Scanning Microscopy revealed that biofilms formed under the induction of Mg(II) had characteristic higher cell densities. The cells remain embedded in thick porous layers of extracellular polymeric substances as evident from the fluorescein isothiocyanate labeled lectin concanavalin A and 4, 6- diamino-2-phenylindole staining. COMSTAT analysis also indicated maximum thickness and roughness coefficient of the biofilm grown in presence of Mg(II). Biofilms of Arthrobacter sp. SUK 1201 developed under such Mg (II) influenced condition showed complete removal of 0.5 mM Cr(VI) in mineral salts medium. The biofilm of this isolate grown in presence of Mg(II) was also able to remove 60µM Cr(VI) from mine seepage water suggesting its possible implication in effective bioremediation of chromium polluted environments.  相似文献   

18.
Osteomyelitis and the role of biofilms in chronic infection   总被引:2,自引:0,他引:2  
Understanding the mechanisms implicated in the initial attachment, development, and maturation of a biofilm phenotype are of tremendous importance for their effect on the medical, industrial, and public health arenas. This review explores the current understanding of the nature of biofilms and the impact that molecular interactions between the bacteria themselves, as well as between bacteria and the host, may have on biofilm development and phenotype using the nonmotile Gram-positive coccus, Staphylococcus aureus, as an example.  相似文献   

19.
Advances in microscopic analysis and molecular genetics research methods promoted the acquisition of evidence that natural bacteria populations exist predominately as substrate attached biofilms. Bacteria in biofilms are able to exchange signals and display coordinated activity that is inherent to multicellular organisms. Formation of biofilm communities turned out to be one of the main survival strategies of bacteria in their ecological niche. Bacteria in attached condition in biofilm are protected from the environmental damaging factors and effects of antibacterial substances in the environment and host organism during infection. According to contemporary conception, biofilm is a continuous layer of bacterial cells that are attached to a surface and each other, and contained in a biopolymer matrix. Such bacterial communities may be composed of bacteria of one or several species, and composed of actively functioning cells as well as latent and uncultured forms. Particular attention has recently been paid to the role of biofilms in the environment and host organism. Microorganisms form biofilm on any biotic and abiotic surfaces which creates serious problems in medicine and various areas of economic activity. Currently, it is established that biofilms are one of the pathogenetic factors of chronic inflection process formation. The review presents data on ubiquity of bacteria existence as biofilms, contemporary methods of microbial community analysis, structural-functional features of bacterial biofilms. Particular attention is paid to the role of biofilm in chronic infection process formation, heightened resistance to antibiotics of bacteria in biofilms and possible mechanisms of resistance. Screening approaches for agents against biofilms in chronic infections are discussed.  相似文献   

20.
The chronic nature of many diseases is attributed to the formation of bacterial biofilms which are recalcitrant to traditional antibiotic therapy. Biofilms are community-associated bacteria attached to a surface and encased in a matrix. The role of the extracellular matrix is multifaceted, including facilitating nutrient acquisition, and offers significant protection against environmental stresses (e.g. host immune responses). In an effort to acquire a better understanding as to how the bacteria within a biofilm respond to environmental stresses we have used a protocol wherein we visualize bacterial biofilms which have formed in an 8-well chamber slide. The biofilms were stained with the BacLight Live/Dead stain and examined using a confocal microscope to characterize the relative biofilm size, and structure under varying incubation conditions. Z-stack images were collected via confocal microscopy and analyzed by COMSTAT. This protocol can be used to help elucidate the mechanism and kinetics by which biofilms form, as well as identify components that are important to biofilm structure and stability.  相似文献   

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