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排序方式: 共有334条查询结果,搜索用时 15 毫秒
331.
Ignacio D. Rodríguez‐Llorente Djamila Gamane Alejandro Lafuente Mohammed Dary Abdelaziz El Hamdaoui Julián Delgadillo Bouchra Doukkali Miguel A. Caviedes Eloísa Pajuelo 《Engineering in Life Science》2010,10(1):49-56
The aim of this work was to establish the conditions for using Ochrobactrum cytisi Azn6.2 as a metal biosorbent. Azn6.2 is a novel strain from the legume symbiont O. cytisi that has been isolated from nodules of Medicago polymorpha plants grown on heavy metal‐polluted soils. Compared with the strain ESC1, Azn6.2 showed some biochemical differences, as well as antibiotic susceptibility, Azn6.2 was multi‐resistant to heavy metals, such as Cu, Cd and Zn, and bacterial pellets were able to biosorb high amounts of Cd and Zn. As shown by scanning electron microscopy coupled to energy dispersive X‐ray, most of Cd was attached to the cell surface. Optimal conditions for Cd biosorption were established, being 1 mM Cd ions in solution and 2 h of contact with the biosorbent at room temperature. At these conditions, maximal Cd loading capacity reached 32–34 mg/g. Cd desorption from bacterial pellets was achieved after washing with EDTA or, at higher efficiency, at pH 1.0. These results indicated that biosorption/desorption on O. cytisi Azn6.2 biomass should be a cost‐effective method for Cd recovery from contaminated solutions. 相似文献
332.
Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component. 相似文献
333.
E. Montesinos A. Bonaterra E. Badosa J. Francés J. Alemany I. Llorente C. Moragrega 《International microbiology》2002,5(4):169-175
Plants constitute an excellent ecosystem for microorganisms. The environmental conditions offered differ considerably between
the highly variable aerial plant part and the more stable root system. Microbes interact with plant tissues and cells with
different degrees of dependence. The most interesting from the microbial ecology point of view, however, are specific interactions
developed by plant-beneficial (either non-symbiotic or symbiotic) and pathogenic microorganisms. Plants, like humans and other
animals, also become sick, but they have evolved a sophisticated defense response against microbes, based on a combination
of constitutive and inducible responses which can be localized or spread throughout plant organs and tissues. The response
is mediated by several messenger molecules that activate pathogen-responsive genes coding for enzymes or antimicrobial compounds,
and produces less sophisticated and specific compounds than immunoglobulins in animals. However, the response specifically
detects intracellularly a type of protein of the pathogen based on a gene-for-gene interaction recognition system, triggering
a biochemical attack and programmed cell death. Several implications for the management of plant diseases are derived from
knowledge of the basis of the specificity of plant-bacteria interactions. New biotechnological products are currently being
developed based on stimulation of the plant defense response, and on the use of plant-beneficial bacteria for biological control
of plant diseases (biopesticides) and for plant growth promotion (biofertilizers).
Electronic Publication 相似文献
334.
In the assays used to determinate the adenine and hypoxanthine-guanine phosphoribosyltransferases activities from Artemia cysts two phases of velocity are observed in the synthesis of AMP, IMP and GMP: one initial burst and a second, slower, steady-state velocity. Both reaction velocities are divalent cation-dependent and temperature-resistant, as they are detectable at temperatures from 0 to 100 degrees C. Butanol, frequently employed to interrupt the purine phosphoribosyltransferase reactions, does not inhibit the enzyme activities. The 'burst' phase is not detected when the reaction is ended by the addition of EDTA. These data support that the initial velocities of these enzymatic reactions may be due to the accumulation of products formed by the overall reaction, developed subsequent to the controlled reaction period, being the 'burst' a result from the relative resistance of these enzymes to the agents that are often used to stop the reaction, such as heat or butanol. 相似文献