芽胞杆菌B13解养分效果研究

目的评价芽胞杆菌B13的功能。方法通过培养基及土壤培养分析其解钾、解磷的效果。结果芽胞杆菌B13培养7d后液体培养基中的有效磷含量（0．94μg／mL）比对照组（0．75μg/mL）增加25．33％,有效钾含量（0．54μg/mL）比对照组（0．31μg／mL）增加74．19％,解磷和解钾差异均有统计学意义（P〈0．01）。芽胞杆菌B13添加在灭菌土壤和不灭菌土壤中都具有明显的解磷、解钾功效,说明芽胞杆菌B13有较好的土壤定植能力。平板解磷试验证明芽胞杆菌B13同时具有解无机磷和有机磷的功效。结论芽胞杆菌B13具有很大的研究与开发价值。     

Method to decompose uncertainties in LCA results into contributing factors

The International Journal of Life Cycle Assessment - Understanding uncertainty is essential in using life cycle assessment (LCA) to support decisions. Monte Carlo simulation (MCS) is widely used to...     

The relative ability of fungi from Sphagnum fuscum to decompose selected carbon substrates

Nine species from a suite of 55 microfungi isolated from living and decomposing Sphagnum fuscum were selected for studies of in vitro decomposition of tannic acid, cellulose, and starch. In vitro decomposition of S. fuscum plants and spruce wood chips was also examined. Oidiodendron maius and Oidiodendron scytaloides degraded tannic acid, giving a positive reaction for polyphenol oxidases. Most taxa degraded cellulose and starch via the synthesis of cellulases and amylase, respectively. Mass losses of spruce wood chips generally exceeded those of S. fuscum. A basidiomycete, similar to Bjerkandera adusta, caused the greatest mass losses in spruce wood chips (10.2%), while O. scytaloides caused the smallest mass losses (3.4%) after 8 weeks. For S. fuscum, Sordaria fimicola caused the greatest (5.1%) and Mucor hiemalis the smallest (0.1%) mass losses after 8 weeks. Filamentous microfungi have considerable potential to decompose a variety of carbon substrates of bryophilous residues in peatlands.     

Nitrated lipids decompose to nitric oxide and lipid radicals and cause vasorelaxation

Nitric oxide-derived oxidants such as nitrogen dioxide and peroxynitrite have been receiving increasing attention as mediators of nitric oxide toxicity. Indeed, nitrated and nitrosated compounds have been detected in biological fluids and tissues of healthy subjects and in higher yields in patients under inflammatory or infectious conditions as a consequence of nitric oxide overproduction. Among them, nitrated lipids have been detected in vivo. Here, we confirmed and extended previous studies by demonstrating that nitrolinoleate, chlolesteryl nitrolinoleate, and nitrohydroxylinoleate induce vasorelaxation in a concentration-dependent manner while releasing nitric oxide that was characterized by chemiluminescence-and EPR-based methodologies. As we first show here, diffusible nitric oxide production is likely to occur by isomerization of the nitrated lipids to the corresponding nitrite derivatives that decay through homolysis and/or metal ion/ascorbate-assisted reduction. The homolytic mechanism was supported by EPR spin-trapping studies with 3,5-dibromo-4-nitrosobenzenesulfonic acid that trapped a lipid-derived radical during nitrolinoleate decomposition. In addition to provide a mechanism to explain nitric oxide production from nitrated lipids, the results support their role as endogenous sources of nitric oxide that may play a role in endothelium-independent vasorelaxation.     

The Ability of Virulence Factor Expression by Pseudomonas aeruginosa to Predict Clinical Disease in Hospitalized Patients

Background

Pseudomonas aeruginosa is an opportunistic pathogen that frequently causes hospital acquired colonization and infection. Accurate identification of host and bacterial factors associated with infection could aid treatment decisions for patients with P. aeruginosa cultured from clinical sites.

Methods

We identified a prospective cohort of 248 hospitalized patients with positive P. aeruginosa cultures. Clinical data were analyzed to determine whether an individual met predefined criteria for infection versus colonization. P. aeruginosa isolates were tested for the expression of multiple phenotypes previously associated with virulence in animal models and humans. Logistic regression models were constructed to determine the degree of association between host and bacterial factors with P. aeruginosa infection of the bloodstream, lung, soft tissue and urinary tract.

Results

One host factor (i.e. diabetes mellitus), and one bacterial factor, a Type 3 secretion system positive phenotype, were significantly associated with P. aeruginosa infection in our cohort. Subgroup analysis of patients with P. aeruginosa isolated from the urinary tract revealed that the presence of a urinary tract catheter or stent was an additional factor for P. aeruginosa infection.

Conclusions

Among hospitalized patients with culture-documented P. aeruginosa, infection is more likely to be present in those with diabetes mellitus and those harboring a Type 3 secretion positive bacterial strain.     

Comparison of some novel polyculture and traditional monoculture vermicomposting reactors to decompose organic wastes

Efforts were made to evaluate the decomposition potentials of traditional monoculture and some novel polyculture vermireactors. Three earthworm species, i.e. Eisenia fetida (E. f.), Perionyx excavatus (P. ex.) and Lampito mauritii (L. m.), representing two different ecological categories: epigeic (E. fetida and P. excavatus) and anecic (L. mauritii), were used to design seven different vermireactors, i.e. Mono-(E. f.), Mono-(P. ex.), Mono-(L. m.), Poly-(E. f. + P. ex.), Poly-(P. ex. + L. m.), Poly-(E. f. + L. m.) and Poly-(E. f. + P. ex. + L. m.). The microbial load of vermireactors was evaluated through measuring dehydrogenises activities (DH-ase) and microbial biomass-N, while mineralization rate was measured in respect to changed level of some important nutrients in vermicomposted substrate. The vermicomposting caused decrease in pH (67.0–15.0%), organic C (46.1–28.4%) and C:N ratio (72.2–57.1%) and increase in total N (137.7–67.8%) as well as available P (107.9–16.9%) contents, at the end. The carbon and nitrogen mineralization rate showed the order: Poly-(E. f. + P. ex. + L. m.) > Poly-(E. f. + L. m.) > Poly-(P. ex. + L. m.) > Poly-(E. f. + P. ex.) > Mono-(E. f.) > Mono-(P. ex.) > Mono-(L. m.) for this study. The Poly-(E. f. + P. ex. + L. m.) vermireactor showed the maximum level of DH-ase activity 1926 ± 245 μg g⁻¹ substrate 24 h as well as microbial biomass-N 3059.1 ± 242.3 mg N g⁻¹ substrate, during experimentation. This study clearly suggests that burrowing earthworms in vermireactor not only promote the microbial colonization, but at the same time also accelerate the mineralization rate in decomposing waste. The polyculture vermicomposting, using burrowing earthworms with epigeics, could be more efficient than traditional monoculture vermireactors to decompose organic waste resources.     

Insect-damaged corn stalks decompose at rates similar to Bt-protected, non-damaged corn stalks

The relative decomposability of corn (Zea mays L.) residues from insect (Bt)-protected hybrids and conventional hybrids cultivated under insect pressure was investigated in two studies. Above-ground biomass, residue macromolecular composition, and stalk physical strength were also measured. In the first decomposition study, chopped residues (stalks and leaves) were used from a corn rootworm-protected (Cry3Bb1) hybrid and its non-Bt near isoline that were grown in replicated plots infested with corn rootworms (Diabrotica spp.). In the second study, residue (intact stalk sections) was used from three European corn borer (ECB, Ostrinia nubilalis Hübner)-resistant (Cry1Ab) hybrids representing different seed manufacturer/maturity date series, their non-Bt near isolines, two Cry3Bb1-protected isolines, and three additional conventional hybrids, all cultivated in replicated plots under conditions of elevated ECB pressure. In both studies, insect-resistant residues decomposed at rates similar to their non-protected near isolines. No evidence was found that insect-protected hybrids produced more above-ground biomass or had distinct residue composition. While some measures of mechanical stalk strength indicated that ECB-damaged stalks were not as stiff as protected stalks, these physical differences did not translate into differences in residue decomposition. We conclude that while individual hybrids may vary in their production of biomass, residue composition or residue decomposability, these characteristics do not systematically vary with the presence of the Bt gene conferring insect resistance, even under conditions of insect pressure.     

General solutions to decompose heterogeneous compositions using antibody afucosylation as a model system

Methods involving the use of mathematical models of competitive ligand—receptor binding to characterize mixtures of ligands in terms of compositions and properties of the component ligands have been developed. The associated mathematical equations explicitly relate component ligand physical–chemical properties and mole fractions to measurable properties of the mixture including steady state binding activity, 1/K_d,apparent or equivalently 1/EC50, and kinetic rate constants k_on,apparent and k_off,apparent allowing: (1) component ligand physical property determination and (2) mixture property predictions. Additionally, mathematical equations accounting for combinatorial considerations associated with ligand assembly are used to compute ligand mole fractions. The utility of the methods developed is demonstrated using published experimental ligand–receptor binding data obtained from mixtures of afucosylated antibodies that bind FcγRIIIa (CD16a) to: (1) extract component ligand physical property information that has hitherto evaded researchers, (2) predict experimental observations, and (3) provide explanations for unresolved experimental observations. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:500–510, 2017     

Ability of Pseudomonas sp. to synthesize aminopeptidases in the presence of various carbon and nitrogen sources

A soil strain of Pseudomonas sp. is able to synthesize at least two aminopeptidases exhibiting high activity in the presence of Phe-beta-NA and Ala-beta-NA as substrates. Irrespective of the used substrate, total activity of studied enzymes was strongly related to concentrations of organic components (peptone, glutamic acid, glucose) in mineral media and was the higher, the higher the concentration. Tendency of changes in total activity was similar for alanyl- and phenylalanylaminopeptidase though their response to different concentrations of organic components was different. Specific activity measured in the presence of Phe-beta-NA and Ala-beta-NA as the substrates was not strictly dependent on increasing concentrations of organic components in the media. The highest specific activity of aminopeptidase was obtained in the presence of Phe-beta-NA as a substrate on the fifth day of culture in medium containing 1% glucose. The obtained results seem to indicate the inductive character of the studied aminopeptidases. On the other hand, however, they do not exclude other regulatory mechanisms of their synthesis, including catabolic repression.     

Orthonormal transform to decompose the variance of a life-history trait across a phylogenetic tree

In recent years, there has been an increased interest in studying the variability of a quantitative life-history trait across a set of species sharing a common phylogeny. However, such studies have suffered from an insufficient development of statistical methods aimed at decomposing the trait variance with respect to the topological structure of the tree. Here we propose a new and generic approach that expresses the topological properties of the phylogenetic tree via an orthonormal basis, which is further used to decompose the trait variance. Such a decomposition provides a structure function, referred to as an "orthogram," which is relevant to characterize in both graphical and statistical aspects the dependence of trait values on the topology of the tree ("phylogenetic dependence"). We also propose four complementary test statistics to be computed from orthogram values that help to diagnose both the intensity and the nature of phylogenetic dependence. The relevance of the method is illustrated by the analysis of three phylogenetic data sets, drawn from the literature and typifying contrasted levels and aspects of phylogenetic dependence. Freely available routines which have been programmed in the R framework are also proposed.     

Effect of Rhamnolipids on Growth of Pseudomonas aeruginosa Mutant Deficient in n-Paraffin-utilizing Ability

Egg white solids freeze-dried with or without the addition of glucose were stored at 50°C under 65 % relative humidity to study the effect of the Maillard reaction on the solubility and heat stability and the formation of aggregates. A stimulative effect on the former properties was observed on the sample with glucose in the initial stage of the Maillard reaction. By comparing the SDS-polyacrylamide gel electrophoretic patterns, solubilities in SDS and SDS/2-mercaptoethanol and the s_20,w values, it was found that glucose, in addition to the effect due to the changes of charged groups in glucose-protein complex occurring in the course of the Maillard reaction, might have a protective effect against aggregate formation through a stable cross-linking, which was not dependent on the SS bond, and through a stable non-covalent bond.     

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids

Three strains (2ac9, 3ac10 and 4ac11) of oval to rodshaped, Gram negative, nonsporing sulfate-reducing bacteria were isolated from brackish water and marine mud samples with acetate as sole electron donor. All three strains grew in simple defined media supplemented with biotin and 4-aminobenzoic acid as growth factors. Acetate was the only electron donor utilized by strain 2ac9, while the other two strains used in addition ethanol and/or lactate. Sulfate served as electron acceptor and was reduced to H₂S. Complete oxidation of acetate to CO₂ was shown by stoichiometric measurements with strain 2ac9 in batch cultures using sulfate, sulfite or thiosulfate as electron acceptors. With sulfate an average growth yield of 4.8 g cell dry weight was obtained per mol of acetate oxidized; with sulfite or thiosulfate the growth yield on acetate was about twice as high. None of the strains contained desulfoviridin. In strain 2ac9 cytochromes of the b- and c-type were detected. Strain 2ac9 is described as type strain of the new species and genus, Desulfobacter postgatei.     

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids

Gliding motility, ultrastructure and nutrition of two newly isolated filamentous sulfate-reducing bacteria, strains 5ac10 and 4be13, were investigated. The filaments were always attached to surfaces. Growth was supported by addition of insoluble aluminium phosphate or agar as substrata for gliding movement. Electron microscopy of ultrathin sections revealed cell walls characteristic of Gramnegative bacteria; the undulated structure of the outer membrane may pertain to the translocation mechanism. Intracytoplasmic membranes were present. Acetate, higher fatty acids, succinate or fumarate served as electron donors and carbon sources. Strain 5ac10 grew also with lactate, but not with benzoate that was used only by strain 4be13. Strain 5ac10 was able to grow slowly on H₂ plus CO₂ or formate in the presence of sulfate without additional organic carbon source. The capacity of complete oxidation was shown by stoichiometric measurements with acetate plus sulfate. Both strains contained b- and c-type cytochromes. Desulfoviridin was detected only in strain 5ac10. The two filamentous gliding sulfate reducers are described as new species of a new genus, Desulfonema limicola and Desulfonema magnum.     

Purification and characterization of a novel cholesterol esterase from Pseudomonas aeruginosa,with its application to cleaning lipid-stained contact lenses

With the aim of developing a new cholesterol esterase for eliminating lipids on used contact lenses, microorganisms were screened for the enzyme activity. A Pseudomonas aeruginosa isolated from soil was found to produce a desirable enzyme. The enzyme had an isoelectric point of 3.2, and molecular mass of 58 kDa. The optimal temperature was around 53 degrees C at pH 7.0, and the optimal pH was from 5.5 to 9.5. The enzyme was stable between pH 5 and 10 for 19 h at 25 degrees C, and retained its activity up to 53 degrees C on 30 min of incubation at pH 7.0. The rates of hydrolysis of cholesteryl esters of different fatty acids were in the following order: linoleate > oleate > stearate > palmitate > caprylate > myristate > laurate, caprate > caproate > butyrate, acetate. Addition of (tauro)cholate to a final concentration of 100 mM markedly promoted the hydrolysis of triglycerides of short-, medium-, and long-chain fatty acids. When used with taurocholate, the enzyme acted as an effective cleaner for contact lenses stained with lipids consisting of cholesteryl oleate, tripalmitin, and stearyl stearate.     

Asymmetry of lysophosphatidylcholine/cholesterol vesicles is sensitive to cholesterol modulation

Sonication of lysophosphatidylcholine (lysoPC; 20 mumol/mL) and cholesterol (chol) in aqueous medium produces lamellar structures over a wide range of concentrations. From 25 to 47 mol % cholesterol, electron microscopy (EM) after negative staining showed extended stacklike lamellae about 40 A thick. From 50 to 60 mol % chol, freeze-fracture EM showed homogeneous populations of small unilamellar vesicles averaging 260-310 A in diameter. Phosphorus-31 nuclear magnetic resonance was used to characterize the stacklike lamellae and to measure the distribution of the lysophospholipid between the outer and inner leaflet of the vesicles as a function of sterol concentration. We found that in lysoPC/chol dispersions containing less than equimolar amounts of cholesterol (25-47 mol %), the entire phosphorus signal (40.5 ppm) was shifted downfield by 10.5 ppm upon addition of Pr3+ (2.4 mM), consistent with the stacklike lamellar structures in which all lysoPC head groups are accessible to the ions. By contrast, addition of Pr3+ to lysoPC/chol vesicles containing equimolar or higher amounts of cholesterol (up to 60 mol %) gave rise to two phosphorus peaks. The more intense downfield signal (51.0 ppm) responsive to paramagnetic ions was assigned to lysoPC located in the outer vesicle leaflet. The upfield signal (40.5 ppm), which was not affected by the ions, was assigned to inside lysoPC. For lysoPC/chol (1:1) vesicles, an outside to inside lysophospholipid ratio (Ro/i) of 6.5 was determined. Essentially the same Ro/i value (6.7) was obtained on lysoPC/chol (1:1) vesicles which after dialysis contained only entrapped Pr3+.(ABSTRACT TRUNCATED AT 250 WORDS)