共查询到20条相似文献，搜索用时 250 毫秒
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供水管道微生物是影响饮用水安全的重要因素,管道生物膜是供水管网微生物风险的主要来源。目前监测供水管道中生物膜微生物风险的研究面临采集困难、培养周期长(3～7 d)等问题,微生物安全预警面临严峻挑战。研究搭建了基于光电装置在线监测的供水管道生物膜实验装置,开展了基于光电信号监测的生物膜生长和脱落过程研究。实验结果表明光电信号反射光强与供水管道生物膜生长脱落之间存在明显的负相关关系,高密度聚乙烯(HDPE)管管道生物膜的生长速度与流速(流速区间0. 2～0. 6 m/s)呈反比例关系,多次冲刷脱落会影响生物膜的耐冲刷能力。 相似文献
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本文在简述当前膜生物学进展的主要成就的基础上,指出膜脂双分子层及其动态性质构成膜结构的主要特征,强调生物膜三大基本功能——物质转移、能量转换和信息传递之间相互联系及统一性,提出生物膜中多种离子泵、离子通道、膜受体及膜融合现象的分子机制的研究对于了解细胞基本生命过程的重要性。在膜生物工程的发展中,膜脂质体生物技术、膜传感和膜生物芯片的研究是当前国际发展上的三个基本趋向。作者在简述国际和我国生物膜研究动态特点的基础上,提出了进一步发展我国近期及中长期膜生物技术的规划和建议。 相似文献
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《中国科技信息》2023,(10):14-16
<正>天津大学研究团队发现调控希瓦氏菌形态构建的杂合生物膜可高效促进产电以电活性微生物（electroactive microorganisms,EAMs）为主导的微生物电化学系统在清洁能源开发、环境和健康监测、可穿戴/植入式设备供电、可持续化学品生产等方面发挥着关键作用。作为EAMs模式菌株,希瓦氏菌（Shewanella oneidensis,S.oneidensis）能够进行细胞外电子转移(extracellular electron transfer,EET),但其EET效率受到电子传递载体浓度低、生物膜形成能力差和生物膜导电性弱等限制,这极大地限制了微生物电化学系统的性能。 相似文献
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生命科学研究总体而言可分为两大方向：对生命实体的研究和对生命之间相互作用的研究。就后者而言,地球上的生命在长期进化过程中形成了相互斗争、相互依赖和相互作用的关系。生物之间的信息流决定着物种间的能量流和物质流的流向,生物间的相互作用构成了寄生、互惠、共生、竞争、拮抗等生态关系,而信息流在它们之间传递的规律是生命存在的基本法则,也构成了生命相互依存最重要的环境条件,其中蕴藏着异常丰富的科学问题。 相似文献
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贺飞鸿 《大科技．科学之谜》2006,(4):21-21
巨大的地球也许是在一眨眼的时间里诞生的!关于地球的形成,目前的主流观点依然是星云假说,太阳系原始星云旋转,分离,中间形成了太阳,周围形成了各大行星,包括地球。地球胚胎在星云物质不断积聚的过程中逐渐壮大,最后形成了原始地球。原始地球一开始是炽热的,后来逐渐冷却,变成了一颗荒凉的、没有水的星球。再往后,才逐渐出现了水、大气和生命。这个早期过程至少要持续几亿年的时间,也就是说,从地球开始形成到生命诞生,经历了相当长的一段岁月。然而,这个目前的流行理论很多环节是猜测的,因为46亿年前地球刚诞生时的岩石等重要资料几乎都没有… 相似文献
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贺飞鸿 《大科技．科学之谜》2006,(5):1-1
关于地球的形成,目前的主流观点依然是星云假说:太阳系原始星云旋转、分离,中间形成了太阳,周围形成了各大行星,包括地球。地球在星云物质不断积聚的过程中逐渐壮大,最后形成了原始地球。原始地球一开始是炽热的,后来逐渐冷却,变成了一颗荒凉的、没有水的星球。再往后,才逐渐出现了水、大气和生命。这个早期过程至少要持续几亿年的时间,也就是说,从地球开始形成到生命诞生,经历了相当长的一段岁月。然而,这个目前流行的理论很多环节是猜测的,因为46亿年前地球刚诞生时的岩石等重要资料几乎没有保留下来,而是在后来的板块运动中被摧毁了,老的… 相似文献
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BackgroundThe past years have witnessed a growing number of researches in biofilm forming communities due to their environmental and maritime industrial implications. To gain a better understanding of the early bacterial biofilm community, microfiber nets were used as artificial substrates and incubated for a period of 24 h in Mauritian coastal waters. Next-generation sequencing technologies were employed as a tool for identification of early bacterial communities. Different genes associated with quorum sensing and cell motility were further investigated.ResultsProteobacteria were identified as the predominant bacterial microorganisms in the biofilm within the 24 h incubation, of which members affiliated to Gammaproteobacteria, Alphaproteobacteria and Betaproteobacteria were among the most abundant classes. The biofilm community patterns were also driven by phyla such as Firmicutes, Bacteroidetes, Chloroflexi, Actinobacteria and Verrucomicrobia. The functional analysis based on KEGG classification indicated high activities in carbohydrate, lipid and amino acids metabolism. Different genes encoding for luxI, lasI, agrC, flhA, cheA and cheB showed the involvement of microbial members in quorum sensing and cell motility.ConclusionThis study provides both an insight on the early bacterial biofilm forming community and the genes involved in quorum sensing and bacterial cell motility. 相似文献
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This paper describes the use of Surface Plasmon Resonance imaging (SPRi) as an emerging technique to study bacterial physiology in real-time without labels. The overwhelming majority of bacteria on earth exist in large multicellular communities known as biofilms. Biofilms are especially problematic because they facilitate the survival of pathogens, leading to chronic and recurring infections as well as costly industrial complications. Monitoring biofilm accumulation and removal is therefore critical in these and other applications. SPRi uniquely provides label-free, high-resolution images of biomass coverage on large channel surfaces up to 1 cm2 in real time, which allow quantitative assessment of biofilm dynamics. The rapid imaging capabilities of this technique are particularly relevant for multicellular bacterial studies, as these cells can swim several body lengths per second and divide multiple times per hour. We present here the first application of SPRi to image Escherichia coli and Pseudomonas aeruginosa cells moving, attaching, and forming biofilms across a large surface. This is also the first time that biofilm removal has been visualized with SPRi, which has important implications for monitoring the biofouling and regeneration of fluidic systems. Initial images of the removal process show that the biofilm releases from the surface as a wave along the direction of the fluid flow. 相似文献
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Mazeyar Parvinzadeh Gashti Julien Bellavance Otini Kroukamp Gideon Wolfaardt Seyed Mohammad Taghavi Jesse Greener 《Biomicrofluidics》2015,9(4)
Time-lapse videos of growing biofilms were analyzed using a background subtraction method, which removed camouflaging effects from the heterogeneous field of view to reveal evidence of streamer formation from optically dense biofilm segments. In addition, quantitative measurements of biofilm velocity and optical density, combined with mathematical modeling, demonstrated that streamer formation occurred from mature, high-viscosity biofilms. We propose a streamer formation mechanism by sudden partial detachment, as opposed to continuous elongation as observed in other microfluidic studies. Additionally, streamer formation occurred in straight microchannels, as opposed to serpentine or pseudo-porous channels, as previously reported. 相似文献
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Maria Salta Lorenzo Capretto Dario Carugo Julian A. Wharton Keith R. Stokes 《Biomicrofluidics》2013,7(6)
In the current study, we have developed and fabricated a novel lab-on-a-chip device for the investigation of biofilm responses, such as attachment kinetics and initial biofilm formation, to different hydrodynamic conditions. The microfluidic flow channels are designed using computational fluid dynamic simulations so as to have a pre-defined, homogeneous wall shear stress in the channels, ranging from 0.03 to 4.30 Pa, which are relevant to in-service conditions on a ship hull, as well as other man-made marine platforms. Temporal variations of biofilm formation in the microfluidic device were assessed using time-lapse microscopy, nucleic acid staining, and confocal laser scanning microscopy (CLSM). Differences in attachment kinetics were observed with increasing shear stress, i.e., with increasing shear stress there appeared to be a delay in bacterial attachment, i.e., at 55, 120, 150, and 155 min for 0.03, 0.60, 2.15, and 4.30 Pa, respectively. CLSM confirmed marked variations in colony architecture, i.e.,: (i) lower shear stresses resulted in biofilms with distinctive morphologies mainly characterised by mushroom-like structures, interstitial channels, and internal voids, and (ii) for the higher shear stresses compact clusters with large interspaces between them were formed. The key advantage of the developed microfluidic device is the combination of three architectural features in one device, i.e., an open-system design, channel replication, and multiple fully developed shear stresses. 相似文献
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Xin Hua Matthew J. Marshall Yijia Xiong Xiang Ma Yufan Zhou Abigail E. Tucker Zihua Zhu Songqin Liu Xiao-Ying Yu 《Biomicrofluidics》2015,9(3)
A vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface), was employed for in situ chemical imaging of live biofilms using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling by sputtering materials in sequential layers resulted in live biofilm spatial chemical mapping. Two-dimensional (2D) images were reconstructed to report the first three-dimensional images of hydrated biofilm elucidating spatial and chemical heterogeneity. 2D image principal component analysis was conducted among biofilms at different locations in the microchannel. Our approach directly visualized spatial and chemical heterogeneity within the living biofilm by dynamic liquid ToF-SIMS.Mapping how metabolic pathways are interconnected and controlled at the subcellular scale within dynamic living systems continues to present a grand scientific challenge. Biofilms, consisting of aggregations of bacterial cells and extracellular polymeric substance (EPS), present an important avenue for deciphering complex microbial communities. During biofilm formation, cells assemble in a secreted polymer milieu of polysaccharides, proteins, glycolipids, and DNA.1,2 Microfluidics provides unprecedented control over flow conditions, accessibility to real-time observation, high-throughput testing, and mimics in vivo biological environments.3 An understanding of the mechanism underlying biofilm formation and the design of advanced microfluidic experiments could address challenges such as interpreting microbial community interactions, biofouling, and resistance to antimicrobial chemicals. However, only a handful of biofilm studies used microfluidic approaches that provided hydrated chemical imaging at high spatial resolution.4–7 Most studies utilized confocal microscopy,4 FTIR spectroscopy,5 or other approaches (e.g., high density interdigitated capacitors7) for biofilm monitoring. Imaging mass spectrometry has been demonstrated in biofilm studies.8,9 A coupled microfluidic-imaging mass spectrometry approach would provide the chemical molecular spatial mapping needed to better address the scientific challenge of biofilms.Recently, we developed a portable microfluidic reactor, System for Analysis at the Liquid Vacuum Interface (SALVI),10,11 which overcame the grand challenge of studying liquids with high volatility and liquid interfaces using surface sensitive vacuum instruments. SALVI enables direct imaging of liquid surfaces using electron or ion/molecular based vacuum techniques. Our microfluidic approach used a polydimethylsiloxane (PDMS) microchannel fully enclosed with a thin silicon nitride (SiN) membrane (100 nm thick). For visualization, 2 μm diameter holes were opened in the SiN membrane in vacuo. These detection windows were dynamically drilled using the time-of-flight secondary ion mass spectrometry (ToF-SIMS) primary ion beam (e.g., Bi+).12Unlike liquid sample holders for transmission electron microscopy and scanning transmission electron microscopy, SALVI is self-contained and portable.13 As a result, it can potentially be used in many finely focused analytical tool with minimal adaptation.10 The analytical performance of SALVI has been demonstrated with a variety of analytes ranging from biology to material sciences.14,15 Unlike most microfluidic applications that are only suitable under ambient conditions (e.g., separations, cell and small amount sample manipulation, and thermal flow-sensors),16–18 SALVI is compatible with both in situ ambient and in vacuo spectroscopy analysis and imaging.19 Biofilms have been successfully cultivated inside the microfluidic channel and imaged using correlative confocal laser scanning microscopy (CLSM) and ToF-SIMS.20Our approach opens a new avenue to study biological sample in their natural state. Although ToF-SIMS has been widely used for providing molecular signatures of organic and biological molecules in complex biological systems21,22 or lipid spatial mapping,23 the vacuum-based ToF-SIMS generally requires solid (either dried24 or cryo treated25) samples. Here, we report ToF-SIMS two dimensional (2D) and three dimensional (3D) chemical images of hydrated biofilms. In situ time and space-resolved identifications of fatty acid (FA) fragments characteristic of Shewanella are illustrated by 3D images reconstructed from the ToF-SIMS depth profile time series. Principal component analysis (PCA) further elucidates biofilm chemical and spatial heterogeneity and shows the key chemical component at different depth and location of the biofilm including the biofilm-surface attachment interface.For all growth experiments, two samples were cultured simultaneously. At days 5 and 6, one sample was harvested for immediate analysis, respectively, using a ToF-SIMS V spectrometer (IONTOF GmbH, Münster, Germany). Similar results were obtained from both samples, because the biofilm-attachment surface was probed. For consistency, only day 6 data are shown here, while additional data are provided in the supplementary material.28 2D and 3D image visualizations were obtained using the IONTOF instrument software. PCA was performed using MATLAB R2012a (MathWorks, Inc., Natick, MA, USA). 2D images of .bif format were converted and integrated into a matrix. Data were pretreated by normalization to total ions, square root transformation, and then mean centering.26 For m/z spectra PCA, unit mass peaks from m/z 199 to m/z 255 were used (see Figure S-228). Unit mass peaks from m/z 1–300 were also used and results are comparable (see Figure S-328). Five characteristic FA peaks (m/z 199, 213, 227, 241, and 255, corresponding to C12, C13, C14, C15, and C16 FAs) were used in image PCA.27 Images representing each PC were reconstructed from the score matrix using the red, green, and blue (RGB) color scale.Using depth profiling, we drilled through the SiN membrane and collected depth-resolved images of the live biofilm (Figure 1(a)). Our analysis of the negative ToF-SIMS spectra after SiN punch-through showed Shewanella FA fragments in the m/z 195–255 range.20 From the depth profile time series, we selected five regions (highlighted as I, II, III IV, and V) within the FA m/z range to visualize 2D spatially resolved images collected for 46 s (1000 scans) before (I), during (II), or after (III, IV, V) SiN membrane punch-through.20 When false color 2D images of FA fragments characteristic of Shewanella biofilms were selected from the dynamic depth profiling data, differences were observed (Figure 1(b)) among the five regions. Furthermore, the biofilm images after SiN membrane punch-through (III, IV, V) displayed variations across the 2 μm diameter surfaces, with C12 (m/z 199) being distributed across regions III, IV, and V and C15 (m/z 241) FAs mostly in region V (see Figure S-4 for additional FA images28). This suggested that depth-resolved chemical heterogeneities were present in the biofilm. To illustrate, we reconstructed the 2D images from depth profiling data within the biofilm region (from the beginning of III through the end of V) and show spatially resolved 3D chemical images within the entire sample (Figure 1(c) and movies S1-S328). The reconstructed 3D images revealed the heterogeneous spatial distribution overlay for C12 (red) and C15 (green) FAs during 302 s biofilm depth profiling from day 5 (Figure S-528) and day 6 (Figure 1(c)).Open in a separate windowFIG. 1.(a) ToF-SIMS depth profiling of the day 6 biofilm attached to the SiN membrane in the microfluidic channel. Five regions representing sample before SiN punch-through (I) during punch-through (II) or within the biofilm region (III, IV, and V) are illustrated. (b) 2D false color images of day 6 biofilm FAs at the five time regions highlighted in (a). (c) Reconstructed 3D day 6 biofilm images showing FA fragment distributions within the entire biofilm region (III–V, 302 s). The time axis represents depth profiling from near the SiN surface into the biofilm. (d) Spectra PCA score plot of day 6 biofilm showing the differences and similarities among selected five regions (m/z 199–255). A 95% confidence limit for each region was defined by an ellipse with the same color to the corresponding region clusters. (e) Loadings of PC1 and PC2 corresponding to (d) and the plot of PC variance contributions.Spectral PCA was used to analyze the m/z spectra. The deepest region (V) into the biofilm was the most different from the other two biofilm regions (III and IV), further confirming the heterogeneities observed in the 2D images (e.g., C12 and C15 FA fragments) contributing most to this spatial difference. In addition, C12 FA fragments played a key role in the biofilms imaged near the SiN membrane attachment surface (III and IV). When inspected individually, C12 FAs were observed throughout the entire biofilm region, suggesting that C12 FA fragments may play a role in biofilm attachment to a surface and they may be main components of EPS throughout the biofilm. In contrast, C15 FAs were more abundant deeper within the biofilm, indicating that they may be more relevant to bacteria cells themselves.Uniform sputtering rate was assumed during depth profiling. To better determine the depth and shape of the SIMS ionization crater, AFM measurements were collected using an agarose sample in the SALVI reactor as a proxy for the biofilms (Figure S-628). The AFM results showed that the 100 nm SiN was drilled through and confirmed that the biofilm interface was probed by ToF-SIMS. Ideally, real-time correlative AFM and ToF-SIMS measurements will be needed due to the self-healing property of biofilms. However, such capability is currently under development.To further analyze chemical differences within biofilms, we performed ToF-SIMS depth profiling at three locations along the microchannel; namely, the inlet, center, and outlet as illustrated in Figure S-1(b).28 At each location, we defined the five regions described in Figure 1(a), and 2D image PCA analysis was conducted on the biofilm region (from the beginning of III through the end of V) to visualize the chemical distributions on day 6. Figure 2(a) shows the loading plots for the m/z peaks that contribute to each PC image (Figure 2(b)). The first three PCs explained 93.79% of the variance within the data. For PC1, the strongest positive loading fragments were C12 and C15 FAs, which are the bright red areas in three PC1 images. The C12 FAs were the main contributor to the green regions in the PC2 image. The strongest loading for PC3 in blue was C14 FAs. Compared to PC1 and PC2, PC3 played a limited contribution to the overall spatial distribution discrimination. The merged images give a demonstration of chemical spatial distribution of key components of biofilms in the liquid microenvironment.Open in a separate windowFIG. 2.(a) Image PCA loading plots illustrating the contribution of each FA peak in the day 6 biofilm at three locations within the microfluidic channel. The variance contributions of each PC are shown at the bottom. (b) Reconstructed false-color 2D PCA images in RGB corresponding to each PC scores at these locations along the microfluidic channel. The RGB composite images of the three key PCs are depicted in the bottom. Only data within the 2 μm diameter circle were considered in analysis.Our results show that SALVI and liquid ToF-SIMS studies of live biofilms offer dynamic, depth-resolved chemical mapping and produce 2D and 3D visualizations of spatial heterogeneity within a biofilm. Chemical imaging of biofilms near the attachment interface can enhance our understanding of biofilm formation in environmental, medical, and industrial settings. Our approach provides a universal portable platform and enables in situ probing of complex living biological systems potentially across multiple time and space scales. Because of the portability and vacuum compatibility, SALVI offers a valuable linkage with proteomic mass spectrometry via microfluidics and a nondestructive package for integrative in situ analysis of live biological systems in system biology. 相似文献
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对循环移动载体生物膜反应器工艺性能进行了研究,通过实验确定了反应器构造、填料填充比,考察了曝气充氧性能,研究结果认为该反应器内的水流状态大致符合理想全混合反应器的流态,并具有较好的节能效果。 相似文献
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Bacterial aggregation and patchiness play an important role in a variety of ecological processes such as competition, adaptation, epidemics, and succession. Here, we demonstrate that hydrodynamics of their environment can lead to their aggregation. This is specially important since microbial habitats are rarely at rest (e.g., ocean, blood stream, flow in porous media, and flow through membrane filtration processes). In order to study the dynamics of bacterial collection in a vortical flow, we utilize a microfluidic system to mimic some of the important microbial conditions at ecologically relevant spatiotemporal scales. We experimentally demonstrate the formation of “ring”-shaped bacterial collection patterns and subsequently the formation of biofilm streamers in a microfluidic system. Acoustic streaming of a microbubble is used to generate a vortical flow in a microchannel. Due to bacteria''s finite-size, the microorganisms are directed to closed streamlines and trapped in the vortical flow. The collection of bacteria in the vortices occurs in a matter of seconds, and unexpectedly, triggers the formation of biofilm streamers within minutes. Swimming bacteria have a competitive advantage to respond to their environmental conditions. In order to investigate the role of bacterial motility on the rate of collection, two strains of Escherichia coli bacteria with different motilities are used. We show that the bacterial collection in a vortical flow is strongly pronounced for high motile bacteria. 相似文献
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The objective of this work was to investigate the influence of hydrodynamics on the growth kinetics of surface-adhering Pseudomonas putida cells. The results showed in particular that under non substrate-limiting conditions, the early step of bacterial apparent growth rate is lower than those measured with suspended cells. Contrary to previously cited authors which explain this behavior to the different adhesive properties of the “daughter”-cells (which makes more probable the detachment of these daughter-cells), in our experimental conditions, that explanation does not hold and we show a clear dependence of growth kinetics with flow conditions, due to the formation of boundary layer concentration at low Reynolds number. These results revealed that using Monod law in the modeling of biofilm growth in fixed-biomass processes should be performed with care. 相似文献