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1.
Polysaccharide differences between planktonic and biofilm-associated EPS from Pseudomonas fluorescens B52 总被引:2,自引:0,他引:2
The polysaccharides associated with free (planktonic) and surface-attached (biofilm) cells from cultures of Pseudomonas fluorescens strain B52 were compared. Variations in the attached matrix due to surface material (glass or stainless steel) were also analyzed. Two digestion methods were used to optimize the recoveries of sugars, uronic acids and acidic substituents. The yield of analyzable material after digestion reached 90% for the material associated to the biofilms, though only 20–30% for that bound to planktonic cells. The polysaccharide(s) in the biofilm had glucuronic and guluronic acids as main components, besides rhamnose, glucose and glucosamine. The proportion of glucuronic to guluronic acid was higher in the polysaccharide(s) found in biofilms formed on stainless steel than in those on glass. 相似文献
2.
A survey of the literature is made for the XPS analysis of food products (mainly spray‐dried powders, which reveal a considerable surface enrichment in lipids) and of microorganisms and related systems (extracellular polymer substances and biofilms). This survey is used as a background for discussions and recommendations regarding methodology. Sample preparation methods reviewed are freeze drying, analysis of frozen hydrated specimens and adsorption of surface‐active biocompounds on model substrates. Peak decomposition is a way to increase the wealth of information provided by the XPS spectra. It should be performed after a check that sample charge stabilization is satisfactory. Moreover, ensuring the precision needed to make comparisons within sets of samples may involve a trade‐off between imposing constraints and generating information. The examination of correlations between spectral data in the light of chemical guidelines is useful to validate or improve peak decomposition and component assignment, and may also upgrade the chemical information regarding speciation. Further upgrading may be achieved by expressing marker XPS data in terms of concentrations of compounds of interest. Different methods of computation are discussed, providing a composition in terms of ingredients, classes of biochemical compounds, or various organic and inorganic compounds. As an alternative or complement to this deterministic approach, multivariate analysis of suitable spectral windows provides spectral components, which may be used for comparing samples, and which may have a direct chemical relevance or be used to identify features of interest. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
I. J. Gnip S. I. Vaitkus V. I. Kersulis S. A. Veyelis 《Mechanics of Composite Materials》2007,43(5):433-444
The results obtained in an experimental investigation of deformability of expanded polystyrene (EPS) under short-term compression
are presented. The density of EPS varied from 13 to 28 kg/m3. The method of design of experiments was used to determine the elastic modulus and the ultimate strain (corresponding to
the end of quasi-linear deformability) under compression stresses operating perpendicularly and parallel to the faces of EPS
products. A graphical interpretation of the models is also presented. Based on the experimental data obtained, it was concluded
that the expanded polystyrene was homogeneous in mutually perpendicular planes with respect to its deformability in compression.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 5, pp. 639–656, September–October, 2007. 相似文献
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5.
J. Burgain J. Scher G. Francius F. Borges M. Corgneau A.M. Revol-Junelles C. Cailliez-Grimal C. Gaiani 《Advances in colloid and interface science》2014
This review gives an overview of the importance of interactions occurring in dairy matrices between Lactic Acid Bacteria and milk components. Dairy products are important sources of biological active compounds of particular relevance to human health. These compounds include immunoglobulins, whey proteins and peptides, polar lipids, and lactic acid bacteria including probiotics. A better understanding of interactions between bioactive components and their delivery matrix may successfully improve their transport to their target site of action. Pioneering research on probiotic lactic acid bacteria has mainly focused on their host effects. However, very little is known about their interaction with dairy ingredients. Such knowledge could contribute to designing new and more efficient dairy food, and to better understand relationships between milk constituents. The purpose of this review is first to provide an overview of the current knowledge about the biomolecules produced on bacterial surface and the composition of the dairy matter. In order to understand how bacteria interact with dairy molecules, adhesion mechanisms are subsequently reviewed with a special focus on the environmental conditions affecting bacterial adhesion. Methods dedicated to investigate the bacterial surface and to decipher interactions between bacteria and abiotic dairy components are also detailed. Finally, relevant industrial implications of these interactions are presented and discussed. 相似文献
6.
The results obtained in investigating the creep of expanded polystyrene (EPS) boards under compressive stress are presented. Power and exponential equations were used for describing creep compliance. It was found that the curves of creep compliance approximated by both equations adequately represent the research results, taking into account the scatter of the experimental data. Based on the calculation and empirical estimate of long-term creep of EPS under compressive stress σc=(0.25–0.45)σ10%, its creep compliance was determined for a period of 10 years in the future. The dependence of on the density of polystyrene boards and the value of long-term compressive stress σc was established. The expected values of creep strain development in expanded polystyrene boards EPS 80–EPS 250 under constant compressive stress σc=(0.25–0.45)σ10% are presented for the prediction period of 10 years. To obtain the expected creep values for any other period of time in the interval of 5T50 years, the values of should be multiplied by the empirical coefficient . 相似文献
7.
Schmid T Burkhard J Yeo BS Zhang W Zenobi R 《Analytical and bioanalytical chemistry》2008,391(5):1899-1905
Due to their direct influence on the stability of bacterial biofilms, a better insight into the nanoscopic spatial arrangement
of the different extracellular polymeric substances (EPS), e.g., polysaccharides and proteins, is important for the improvement
of biocides and for process optimization in wastewater treatment and biofiltration. Here, the first application of a combination
of confocal laser-scanning microscopy (CLSM) and atomic force microscopy (AFM) to the investigation of river-water biofilms
and related biopolymers is presented. AFM images collected at selected areas of CLS micrographs dramatically demonstrate the
heterogeneity of biofilms at the nanometer scale and the need for a chemical imaging method with nanoscale resolution. The
nanostructures (e.g., pili, flagella, hydrocolloids, and EPS) found in the extracellular matrix are classified according to
shape and size, which is typically 50–150 nm in width and 1–10 nm in thickness, and sets the demands regarding spatial resolution
of a potential chemical imaging method. Additionally, thin layers of the polysaccharide alginate were investigated. We demonstrate
that calcium alginate is a good model for the EPS architecture at the nanometer scale, because of its similar network-like
structure.
Figure CLSM-AFM allows imaging of nanometer-sized extracellular structures 相似文献
8.
Effect of Juglone against Pseudomonas syringae pv Actinidiae Planktonic Growth and Biofilm Formation
Qiqi Han Luoluo Feng Yani Zhang Runguang Zhang Guoliang Wang Youlin Zhang 《Molecules (Basel, Switzerland)》2021,26(24)
Pseudomonas syringaepv Actinidiae (P. syringae) is a common pathogen causing plant diseases. Limoli proved that its strong pathogenicity is closely related to biofilm state. As a natural bacteriostatic agent with broad-spectrum bactericidal properties, juglone can be used as a substitute for synthetic bacteriostatic agents. To explore the antibacterial mechanism, this study was carried out to examine the inhibitory effect of juglone on cell membrane destruction, abnormal oxidative stress, DNA insertion and biofilm prevention of P. syringae. Results showed that juglone at 20 μg/mL can act against planktogenic P. syringae (107 CFU/mL). Specially, the application of juglone significantly damaged the permeability and integrity of the cell membrane of P. syringae. Additionally, juglone caused abnormal intracellular oxidative stress, and also embedded in genomic DNA, which affected the normal function of the DNA of P. syringae. In addition, environmental scanning electron microscope (ESEM) and other methods showed that juglone effectively restricted the production of extracellular polymers, and then affected the formation of the cell membrane. This study provided a possibility for the development and utilization of natural juglone in plants, especially P. syringae. 相似文献
9.
利用高效离子交换色谱(HPIEC)技术结合形态观察和胞外多糖(EPS)含量测定,比较分析青枯雷尔氏菌无致病力突变菌株FJAT-91⊿epsD与强致病力出发菌株FJAT-91及自然致弱的无致病力菌株FJAT-1458的异质性。结果表明,菌株FJAT-91⊿epsD与菌株FJAT-91在菌落和菌体形态上均有明显差异,与菌株FJAT-1458的形态相似。胞外多糖含量测定结果表明,菌株FJAT-91⊿epsD的EPS含量((12.64±1.46)μg/mL)显著低于菌株FJAT-91((30.49±2.97)μg/mL),与菌株FJAT-1458的EPS含量((11.30±1.38)μg/mL)相当。高效离子交换色谱分离结果表明,菌株FJAT-91、FJAT-91⊿epsD和FJAT-1458形成的色谱峰个数和保留时间不同,菌株FJAT-91只有单一色谱峰P3,保留时间为6.04 min;菌株FJAT-91⊿epsD有P1和P2两个色谱峰,保留时间分别为0.59 min和4.62 min;菌株FJAT-1458只有单一色谱峰P1,保留时间为0.59 min。对不同色谱峰回收培养,并对回收培养后的菌株进行致病力鉴定。结果表明,番茄植株接种菌株FJAT-91-P3后第4 d开始发病,第10 d发病率达100%;植株接种菌株FJAT-91⊿epsD-P2后第9 d开始发病,第20 d发病率达100%;植株接种菌株FJAT-1458-P1和菌株FJAT-91⊿epsD-P1后,在观察期内均未发病。研究结果可为利用菌株FJAT-91⊿epsD防治作物青枯病提供理论依据。 相似文献
10.
In this study, the interaction of calcium, magnesium, and sodium as well as impact of monovalent to divalent (M/D) cation ratio and magnesium to calcium (Mg/Ca) ratio in the feed wastewater on membrane fouling in submerged membrane bioreactor (MBR) was investigated. The protein and carbohydrate content of soluble microbial products (SMP) and extracellular polymeric substances (EPS) as well as their relative hydrophobicities was examined. The mixed liquor and its components (soluble and suspended solids) were analyzed for their filtration resistance, as reflected by the modified fouling index (MFI). Based on the findings of this study, the optimum conditions with respect to fouling rate were calcium and sodium concentrations of 36 and 140 mg/L, respectively, M/D of 1:1 and Mg/Ca of 5:1, with all parameters on an equivalent basis. High sodium concentration at high M/D ratio was found to decrease the floc size and increase the fouling rate. At the low M/D ratio of 1:1, introduction of magnesium was beneficial in reducing the fouling rate by increasing the EPS concentration and floc size and decreasing the SMP concentration and relative hydrophobicity in the supernatant. The fouling rate was found to be statistically correlated with the concentrations of Ca, Mg, and Na, with both Ca and Na adversely impacting fouling and Mg alleviating fouling propensity. 相似文献