Surface free energy effect on bacterial retention

Bacterial infection is one of the most frequent and severe complications in the long-term effectiveness of medical implants and devices, greatly increasing treatment cost and inconvenience to the patient. Surface physical and chemical properties are known to influence the extent and form of bacterial infection, although the exact correlation with specific properties is difficult due to the complexity of the system. One approach in the attempt to reduce the bacterial colonisation is to modify the surface energy and chemistry, so as to influence the interactions between the surface and the bacteria that come into contact with it. Five types of coatings were investigated in this study, together with silicone, and polished and non-polished stainless steel 316L. Surfaces were tested for retention of Pseudomonas aeruginosa AK1 after 1 h. A good correlation (>90%) was found between P. aeruginosa AK1 retention and total surface free energy, as well as its polar and dispersive components. The minimum level of P. aeruginosa AK1 retention was found for a range of total surface free energy in the range 20–27 mN/m.     

Adsorption of Pseudomonas putida on clay minerals and iron oxide

Adsorption of Pseudomonas putida on minerals including montmorillonite, kaolinite and goethite was studied. The adsorption isotherms of P. putida on the examined minerals conformed to the Langmuir equation. The amount of P. putida adsorbed followed the order: goethite > kaolinite > montmorillonite. A greater extent of P. putida adsorption on minerals was observed in the range of temperature from 15 to 35 °C. The adsorption of P. putida on minerals decreased with the increase of pH from 3.0 to 10.0. Magnesium ion was more efficient than sodium ion in promoting P. putida adsorption on minerals. The results suggest that electrostatic interactions play a vital role in P. putida adsorption by soil colloidal factions. The information obtained in this study is of fundamental significance for the understanding of the survival and transport of bacteria in soil systems.     

Selective adsorption of bacterial cells onto zeolites

Zeolites adsorb microbial cells on their surfaces and selective adsorption for specific microorganisms was seen with certain zeolites. Tests for the adsorption ability of zeolites were conducted using various established microbial cell lines. Specific cell lines were shown to selectively absorb to certain zeolites, species to species.

In order to understand the selectivity of adsorption, we tested adsorption under various pH conditions and determined the zeta-potentials of zeolites and cells. The adsorption of some cell lines depended on the pH, and some microorganisms were preferentially adsorbed at acidic pH. The values of zeta-potentials were used for calculating the electric double layer interaction energy between zeolites and microbial cells. There was a correlation between the experimental adsorption results and the interaction energy. Moreover, we evaluated the surface hydrophobicity of bacterial cells by using the microbial adherence to hydrocarbon (MATH) assay. In addition, we also applied this method for zeolites to quantify relative surface hydrophobicity. As a result, we found a correlation between the adsorption results and the hydrophobicity of bacterial cells and zeolites. These results suggested that adsorption could be explained mainly by electric double layer interactions and hydrophobic interactions.

Finally, by using the zeolites Na-BEA and H-Y, we succeeded in clearly separating three representative microbes from a mixture of Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Zeolites could adsorb each of the bacterial cell species with high selectivity even from a mixed suspension. Zeolites can therefore be used as effective carrier materials to provide an easy, rapid and accurate method for cell separation.     

壳寡糖氨基硫脲席夫碱铜的制备及其抗真菌活性

以壳寡糖为原料,采用一锅法合成壳寡糖氨基硫脲,然后再与吡啶甲醛经缩合反应合成壳寡糖氨基硫脲席夫碱,最后与铜离子发生配位反应合成目标化合物壳寡糖氨基硫脲席夫碱铜。 采用红外光谱仪(FTIR)、紫外可见光谱仪(UV-Vis)、核磁共振波谱仪(NMR)、电感耦合等离子体质谱仪(ICP-MS)和热重-差热分析(TG-DTA)对壳寡糖衍生物进行结构表征。 同时采用体外菌丝生长速率法测定壳寡糖及其衍生物对辣椒疫霉菌、烟草黑胫菌、禾谷镰刀菌的体外抗真菌活性。 结果表明,壳寡糖氨基硫脲席夫碱铜质量浓度为1.0 g/L时,对辣椒疫霉、烟草黑胫、禾谷镰刀菌的抑菌率分别为74.19%、56.60%和66.60%,均优于壳寡糖。     

Targeted Synthesis of Anthranilic Diamides Insecticides Containing Trifluoroethoxyl Phenylpyrazole

Aseries of novel anthranilic diamides analogues(9a-9t) containing trifluoroethoxyl pyrazole moiety was designed and synthesized and their insecticidal bioactivities against Mythimna separata(Walker, M. separata) and Plutellaxylostella (P. xylostella) were evaluated. The structures of the title compounds were confirmed by ¹H NMR, ¹³C NMR and HRMS. Preliminary insecticidal activities showed that some of the title compounds possessed good to excellent bioactivities towards M. separata and P. xylostella. Compounds 9c and 9t exhibited 100% mortality rate against M. separate at 0.2 mg/L. For the P. xylostella, the synthesized compounds(9c-9e, 9i and 9o) showed 70%, 80%, 75%, 65% and 60% insecticidal activities at 1×10^-6 mg/L, respectively, higher than that of chlorantraniliprole(0). Based on excellent insecticidal activities, the mode of the action was tested by the calcium-imaging technique, the results of which demonstrated that the novel compounds shared the same target with chlorantraniliprole. The binding pose of the most active compound 9t in RyRs of P. xylostella was predicted by molecular docking, which showed that compound 9t interacted with the residues Glu140(A) and His147(A) via hydrogen bond.     

Utilization of agro-resources by radiation treatment -production of animal feed and mushroom from oil palm wastes

The production of animal feeds and mushrooms from oil palm cellulosic wasres by radiation and fermentation has been investigated in order to utilize the agro-resources and to reduce the smoke pollution. The process is as follows: decontamination of microorganisms in fermentation media of empty fruit bunch of oil palm (EFB) by irradiation, inoculation of useful fungi, and subsequently production of proteins and edible mushrooms. The dose of 25 kGy was required for the sterilization of contaminating bacteria whereas the dose of 10 kGy was enough to eliminate the fungi. Among many kinds of fungi tested, C. cinereus and P. sajor-caju were selected as the most suitable microorganism for the fermentation of EFB. The protein content of the product increased to 13 % and the crude fiber content decreased to 20% after 30 days of incubation with C. cinereus at 30°C in solid state fermentation. P. sajor-caju was suitable for the mushroom production on EFB with rice bran.     

Immobilization of heavy metals by Pseudomonas putida CZ1/goethite composites from solution

Bacterial–mineral composites are important in the retention of heavy metals due to their large sorption capacity under a wide range of environmental conditions. This study provides the first quantitative comparison of the metal-binding capacities of P. putida CZ1–goethite composite to its individual components. When the same amount (on a dry weight basis) of living and nonliving cells of P. putida CZ1, goethite or their composites was separately exposed to solutions of 0.5 mM Cu(II) and Zn(II) in 0.01 M KNO₃, the living cells removed the largest quantity of heavy metals. The results of calculated metal retention values indicated that the adsorption of goethite to bacteria has not mask or neutralize chemically reactive adsorption sites normally available to metal ions. Moreover, the nonliving cells–goethite composite retained approximately 82% more Zn than that predicted by their individual behavior. The preferential association of Zn with P. putida CZ1 was observed by TEM and EDS analyses of a mixture consisting of the bacteria and goethite. Desorption of Cu and Zn with 1.0 M CH₃COOK solution from P. putida CZ1 and goethite indicated the differences in the functional groups able to bind heavy metals.     

古菌脂质的前处理方法比较及超高效液相色谱-高分辨质谱分析

古菌是一类兼具真菌及细菌细胞特征、大多生活在极端环境下的单细胞微生物。由于膜结构及代谢通路的特殊性,研究古菌脂质对深入探究极端环境下生命的正常活动具有重要意义。前处理方法在组学分析中会极大影响最终结果的准确度及可靠性。该文基于超高效液相色谱-高分辨质谱联用（ultra-performance liquid chromatography-high resolution mass spectrometry,UPLC-HRMS）技术,以嗜热嗜压古菌Pyrococcus yayanosii为模式生物,采用Bligh-Dyer加酸法、Folch法、甲基叔丁基醚（methyl tert-butyl ether,MTBE）法及固相萃取（SPE）法提取脂质成分,从提取效率、重复性、歧视性等角度进行方法评价,并最终确定SPE法和MTBE法的提取重复性和提取效率最好,适合高通量古菌全脂质提取。利用SPE提取、高分辨质谱分析对P.yayanosii的常规脂质进行了全面分析,共鉴定到了1402种脂质。本研究旨在为古菌和其他极端微生物的非靶向脂质组学分析和脂质代谢研究提供方法参考。     

Surface forces and the stability of colloids and disperse systems

There are discussed two factors controlling the thickness h of a free film of liquid between two bubbles of radius R pressed against one another, the mechanical properties of the film and the temperature. The role of the viscosity, η, is analyzed on the basis of the formula h = 2.64 R(ηu/σ)^2/3 (σ surface tension, u thereceding velocity of the film perimeter), which is the simple consequence of the formula for the thickness of the film left behind the receding wetting perimeter (Derjaguin, 1943). A similar formula is also used for the analysis of the role of yield value of the film. The temperature does not change the thickness of the black free films (100A.) in contrast to the thicker films governed by electric repulsion. The jumpwise thinning of free films is studied by microfilming.

The method of crossed polarized metal wires is described, which permits measurement of the potential barrier preventing metallic contact in liquid media. The measurements of this barrier in water solutions of electrolytes as a function of potential of the wires are interpreted on the basis of our theory of colloid stability. The existence of repulsive forces (disjoining pressure) at high electrolyte concentrations independent of the potential proves their nonelectrostatic origin. These measurements were also used to calculate Hamaker's constant of molecular attraction and to determine the potential of zero charge of some metals.     

Design and Synthesis of Novel 3,4-Dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides-based Strobilurins as Potent Fungicide Candidates

To discover novel strobilurins analogues with good and broad spectrum activity, a series of novel 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides-based strobilurins was designed, synthesized, and tested against various phytopathogenic fungi. Compounds 7b, 7c, and 7k exhibited substantial and broad spectrum antifungal activities against the tested phytopathogenic fungi, especially compound 7b, which showed 100%, 80%, 90%, and 90% antifungal activity(in virto) against Erysiphe graminis(E. graminis), Puccinia sorghi Schw.(P. sorghi Schw.), Colletotrichum lagenarium(C. lagenarium), and Pseudoperonospora cubensis(P. cubensis) at 300 μg/mL, respectively, better or comparable to the positive control azoxystrobin. Moreover, compound 7b exhibited 85% greenhouse inhibition activity(in vivo) against E. graminis even at 0.2 μg/mL, equal to azoxystrobin(90%) and trifloxystrobin(90%). Meanwhile, compound 7b against P. cubensis displayed 70% and 55% greenhouse inhibition activity(in vivo) at 1.56 and 0.2 μg/mL, respectively, much better than those of azoxystrobin and trifloxystrobin(both 0% at 1.56 and 0.2 μg/mL). Therefore, compound 7b could be considered as the most promising fungicidal candidate for further study. Furthermore, based on the effective concentration(EC₅₀) against C. arachidicola, the built CoMSIA model provided the useful reference for the further structural optimization design.     

Influence of sialic acid and bacterial sialidase on differential adhesion of Pseudomonas aeruginosa to epithelial cells

Epithelial cell lines from several tissues show a differential sensitivity to Pseudomonas aeruginosa adherence. A549 (lung), HepG2 (liver) and Caco-2 (colon) cells presented an adhesion index of about 3, 1.5 and 5 CFU/cell, respectively, whereas Mz-Ch cell lines (gallbladder cholangiocytes) presented adhesion indexes up to 35. These variations could be associated with the variable amount of sialic acid in cell surface glycoconjugates. Moreover, the presence of free sialic acid in culture media induces the secretion by P. aeruginosa of a sialidase which is able to hydrolyze glycoconjugate-linked sialic acid. As shown with A549 cells, this specific hydrolysis increases bacterial adhesion, probably by unmasking new binding sites onto the cell surface.     

Phase behavior and surface tensions of amphiphilic fluorinated random copolymer aqueous solutions

Phase behavior and surface tension of aqueous solutions of fluorinated random copolymers [perfluoroalkylacrylate]–[poly(ethyleneoxide)methacrylate], [C_mRf-acrylate]-[EO_n-methacrylate] with fluroalkyl carbon number m = 8, 6, 4, 2 and number of ethyleneoxide unit, n = 9 and 4.5 were investigated as a function of composition and different combinations of m and n. Isotropic solutions are formed at lower temperatures over wide concentration range of copolymer but at higher temperature phase separation occurs. The cloud point of copolymer decreases with decreasing n as well as m, and also with decreasing the number of poly(ethyleneoxide)methacrylate chain per perfluorinatedalkylacrylate chain, suggesting that the copolymers become more hydrophobic on decreasing m and n. Equilibrium and dynamic surface tension measurements show that copolymers become increasingly surface active as m as well as n decrease but the adsorption at the air–water interface is very slow due to bulkiness of the molecules. No clear evidence of the formation of micellar aggregates could be obtained from surface tension–composition curves.     

Oxidations of erogorgiaene in pseudopterosin biosynthesis

Pseudopterosins are potent anti-inflammatory diterpene glycosides initially isolated from the gorgonian coral Pseudopterogorgia elisabethae. In continuation of pathway elucidation studies focused on this family of terpenes, we report the isolation of 7-hydroxyerogorgiaene and 7,8-dihydroxyerogorgiaene from P. elisabethae and confirm the intermediacy of these compounds in pseudopterosin biosynthesis by in vitro incubation experiments with these metabolites in radiolabeled form.     

Synthesis and coordination of 2-diphenylphosphinopicolinamide

The synthesis and coordination of 2-diphenylphosphinopicolinamide (dpppa 1) is reported. Coordination complexes with Pd, Pt, Ru, Rh, Ir and Au are described. The ligand behaves as a monodentate P donor in complexes such as [PtCl₂(dpppa-P₂)], [PdCl(allyl)(dpppa-P)], [RuCl₂(p-Cymene)(dpppa-P)], cis-[PtCl₂(dpppa-P)(PR₃)] and [AuCl(dpppa-P)]. Bidentate P, O coordination was accomplished by reaction of BuLi with [RuCl₂(p-Cymene)(dpppa-P)], to give [RuCl(p-Cymene)(dpppa-P,O). P,N donor behaviour was achieved by reaction of a monodentate complex with a halide abstractor [AgBF₄] generating [RuCl(p-Cymene)(dpppa-P,N)][ClO₄] and[RhCl(η⁵-C₅Me₅)(dpppa-P,N)][BF₄]. The X-ray structures of dpppa, dpppaO, dpppaS, four monodentate complexes and [RuCl(p-Cymene)(dpppa-P,O) are reported. All of the structures contain intramolecular N–HN hydrogen bonding.     

Adsorption at the air-water interface and emulsification properties of grain legume protein derivatives from pea and broad bean

Functional properties of native and modified (through induced autolysis) pea (Pisum sativum L.) and broad bean (Vicia faba L.) protein derivatives are studied. In specific, protein solubility and behavior at the air–water interface through surface pressure measurements are investigated. Furthermore the ability of the protein products to act as emulsifying agents and to stabilize emulsions is studied through oil droplet size distribution measurements and by the protein adsorbed at the oil–water interface. The data reveal that the ability of the proteins to act as surfactants and build up a rigid film around the oil droplets, mainly depends on their suitable molecular configuration and structure. Hydrolysis did not promote the functionality of the legume proteins. Broad bean exhibited better functionality than pea, before and after hydrolysis. Some comparisons were also made with lupin (Lupinus albus L.) protein isolate.     

Interaction of Bauhinia monandra lectin (BmoLL) with lipid monolayers

The interfacial behavior of the hypoglycemia lectin BmoLL purified from the leaves of Bauhinia monandra, and its ability to interact with lipid monolayers has been studied by surface tension (γ) measurements. The results of these experiments revealed that in the solution concentration range comprised between 0.2 and 1.0 mg/ml, there was an extremely pronounced increase in the BmoLL adsorption at the interface with the air phase. This adsorption at the higher studied BmoLL concentrations gave rise to a more gradual increase in the surface pressure (π = γ₀−γ). The results showed also that the surface pressure of adsorbed films was pH dependent and it substantially increased at low pHs (between pH 4.0 and pH 2.5). Independently carried out ξ potential measurements demonstrated that BmoLL was negatively charged at all pHs and borne the highest charge at the pH around 5.5. The penetrant ability of BmoLL into the two different in chemical nature monolayers: (dioleoylphosphatidylcholine and octadecylamine) have been assessed measuring Δπ increments at constant area. It was observed that, whereas the monolayers of either pure dioleoylphosphatidylcholine (DOPC) or pure octadecylamine (ODA) stimulated BmoLL adsorption, the lectin adsorption within their mixtures strongly depended on both the content of positively charged octadecylamine in a mixture and on the monolayer compressibility. These findings are discussed in terms of both the electrostatic interaction involved in adsorption of BmoLL and of changes in monolayer compressibilities brought up by the addition of ODA molecules to the phospholipid. The relevance of this work to liposome preparations is indicated in the concluding remarks.     

Interaction of Pseudomonas putida with kaolinite and montmorillonite: a combination study by equilibrium adsorption, ITC, SEM and FTIR

Equilibrium adsorption along with isothermal titration calorimetry (ITC), Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM) techniques were employed to investigate the adsorption of Pseudomonas putida on kaolinite and montmorillonite. A higher affinity as well as larger amounts of adsorption of P. putida was found on kaolinite. The majority of sorbed bacterial cells (88.7%) could be released by water from montmorillonite, while only a small proportion (9.3%) of bacteria desorbed from kaolinite surface. More bacterial cells were observed to form aggregates with kaolinite, while fewer cells were within the larger bacteria–montmorillonite particles. The sorption of bacteria on kaolinite was enthalpically more favorable than that on montmorillonite. Based on our findings, it is proposed that the non-electrostatic forces other than electrostatic force play a more important role in bacterial adsorption by kaolinite and montmorillonite. Adsorption of bacteria on clay minerals resulted in obvious shifts of infrared absorption bands of water molecules, showing the importance of hydrogen bonding in bacteria–clay mineral adsorption. The enthalpies of −4.1 ± 2.1 × 10⁻⁸ and −2.5 ± 1.4 × 10⁻⁸ mJ cell⁻¹ for the adsorption of bacteria on kaolinite and montmorillonite, respectively, at 25 °C and pH 7.0 were firstly reported in this paper. The enthalpy of bacteria–mineral adsorption was higher than that reported previously for bacteria–biomolecule interaction but lower than that of bacterial coaggregation. The bacteria–mineral adsorption enthalpies increased at higher temperature, suggesting that the enthalpy–entropy compensation mechanism could be involved in the adsorption of P. putida on clay minerals. Data obtained in this study would provide valuable information for a better understanding of the mechanisms of mineral–microorganism interactions in soil and associated environments.     

The crystal and molecular structure of N′-monomethylthiobinupharidine iodide dihydrate - the methiodide of nuphar alkaloid

The crystal structure of N′-monomethylthiobinupharidine iodide dihydrate has bee determined by single-crystal X-ray analysis. The crystals are orthorhombic, space group P2₁2₁2₁, with = 9.499(3), b = 15.522(5), c = 23.694(7) A. Block-diagonal least-squares refinement, with 2060 reflections measured on diffractometer, yielded a final value for R of 0.073. The cation was found to have a skeleton composed of two trans-quinolizidine systems with equatorially bonded methyl and furan groups; the central part of the cation (the tetrahydrothiophene ring) adopts a conformation between envelope and half-chair. Quaternization at the N(5′) atom does not change conformation of the quinolizidine. The results of X-ray analysis confirm the interpretation of the ¹³C NMR spectra.     

Asymmetric acyloin condensation catalyzed by phenylpyruvate decarboxylase

Cells obtained from growth of Achromobacter eurydice, Pseudomonas aromatica and Pseudomonas putida on -phenylalanine containing medium catalyzed the enzymatic acyloin condensation of phenylpyruvic acid 1 and acetaldehyde 2 by phenylpyruvate decarboxylase to produce 3-hydroxy-1-phenyl-2-butanone 3. The acyloin condensation by Achromobacter eurydice and P. aromatica was stereoselective, providing the 3R enantiomer 3a with enantiomeric excess (ee) of 95% and 84%, respectively. A partially purified enzyme was prepared from the cell free extract of Achromobacter eurydice. The acyloin product 3a was obtained in 45% yield with an ee of 91% by using this partially purified preparation of phenylpyruvate decarboxylase.     

Action of Humicola lanuginosa lipase on long-chain lipid substrates: 1. Hydrolysis of monoolein monolayers

The hydrolysis of 1-monoolein (MO) monomolecular films by Humicola lanuginosa lipase (HLL) was followed by measuring the simultaneous decrease with time in the film area and the surface potential using a ‘zero order trough’ at constant surface pressure (Verger and de Haas, Chem. Phys. Lipids 10 (1973) 127). The decrease with time in the film area reflects both the reduction in the area per molecule as well as the solubilization of the substrate and the product molecules during the transformation of the substrate MO into product of oleic acid (OA). The surface potential changes were interpreted as the results of the accumulation at the interface of negatively charged OA. The surface concentration of OA transiently present at the interface was determined by the surface pressure and the surface potential measurements on the basis of a developed kinetic model. In the proposed model we have taken into account the product and substrate solubilization rates in the presence of β-cyclodextrin (β-CD) as well as the flux supplied progressively by the moving barrier from the reservoir to the reaction compartment in order to keep the constant surface pressure. Values of the global kinetic constant Q_m were obtained. The selective lipolytic product acceptor, β-CD, accelerated considerably the hydrolytic process.