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dissipation measured by calorimetry represents a suitable procedure to monitor metabolic activity. [ 2 ]. Biocalorimetry has been applied to investigate metabolic activity of heterotrophic and autotrophic nitrifying bacterial populations in sludge samples from

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A preliminary study was conducted to compare the community level physiological profile (CLPP) and genetic diversity of rhizosphere microbial communities of four plant species growing nearby Kiskunság soda ponds, namely Böddi-szék, Kelemen-szék and Zab-szék. CLPP was assessed by MicroResp method using 15 different substrates while Denaturing Gradient Gel Electrophoresis (DGGE) was used to analyse genetic diversity of bacterial communities. The soil physical and chemical properties were quite different at the three sampling sites. Multivariate statistics (PCA and UPGMA) revealed that Zab-szék samples could be separated according to their genetic profile from the two others which might be attributed to the geographical location and perhaps the differences in soil physical properties. Böddi-szék samples could be separated from the two others considering the metabolic activity which could be explained by their high salt and low humus contents. The number of bands in DGGE gels was related to the metabolic activity, and positively correlated with soil humus content, but negatively with soil salt content. The main finding was that geographical location, soil physical and chemical properties and the type of vegetation were all important factors influencing the metabolic activity and genetic diversity of rhizosphere microbial communities.

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Abstract  

After a formal explanation of Mayer's enthalpy balance method as applied to biological reaction rates, the history of its application is traced from Rubner's dog to accounting for the energy of muscle contraction. The introduction of microcalorimetry allowed the method generally to be used for cells in vitro and now particular emphasis can be paid to the growth of cells for the production of therapeutically-important heterologous proteins. In these systems, enthalpy balance studies contribute to defining catabolic processes, designing media, understanding the mechanisms of growth and controlling cultures using heat flux as an on-line sensor of metabolic activity.

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Inoculating wheat (cv. Giza 164) with various Fusarium species had different effects on the catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) activity in different plant tissues. The CAT activity induced in the shoots of wheat plants by some pathogens (F. merismoides, F. moniliforme, F. poae and F. sambucinum) was relatively higher than that induced by other pathogens. The results showed an increase in POX activity in infected shoots except those inoculated with F. sambucinum, where the POX activity decreased. Inoculating wheat plants with individual Fusarium species or with a mixture of pathogens caused an increase in APX in the shoots, except for those treated with F. poae, where the APX activity decreased. The activity of these antioxidant enzymes thus increased in most cases in the shoot system of wheat plants under Fusarium infection. Investigations on the metabolic activity of wheat plants inouculated with individual Fusarium species or with a mixture of pathogens showed higher contents of all the protein fractions, soluble sugars, total free amino acids and proline. The K+ and Ca2+ concentrations decreased to various extents in different cases. The Na+ content increased in wheat shoots, especially after inoculation with F. merismoides. The results signify that the most serious infection was caused by F. culmorum, F. graminearum and F. oxysporum and by a mixture of all the Fusarium species.

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Paeonia decomposita is a perennial deciduous shrub with great ornamental and medicinal values. Unfortunately, the distribution region, population size and individual numbers of P. decomposita rapidly decrease in the wild. It is a particularly rare, highly endangered, protective plant endemic to Southwest China. To understand the causes of seed dormancy of P. decomposita, the effects of aqueous extracts of the seed coat, endosperm of P. decomposita on germination, seedling growth and amylases activities of wheat seeds were examined in this paper. The results showed that the seed, especially the endosperm tissue of P. decomposita contained substances that strongly suppressed seed germination. The crude extract of endosperm of P. decomposita, which significantly reduced the activities of α and β-amylase, showed a more significant inhibition than that of seed coat at the same dose. It was concluded that the presence of inhibitory substances in seed, especially in endosperm tissue, seem to be responsible for P. decomposita seed dormancy.

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The impact of the combined stress factors of heavy metals (cadmium and nickel) and UV A+B radiation in Pisum sativum was investigated. Seeds were grown in sandy loam for 30 days, and then randomly divided into equal two groups. The first group was exposed for 5 hours/day to supplemental 6.4 KJ m −2 d −1 dose UV A+B radiation beside white light (1,100 Lux), while the second one was exposed to white light only giving light intensity (1,100 Lux). Plants from each group were irrigated with nutrient solution having 0.0, 5, 10 and 20 μmol Cd or Ni for two weeks and then harvested. The results showed that, Cd or Ni treatments induced significant decreased the length, fresh weight, dry weight and density of both root and shoot. UV A+B resulted in synergistic inhibitory effects of all measured growth parameters. Total chlorophyll, carotenoids, total carbohydrates and proteins showed a similar pattern to that of growth parameters. The amount of UV-screening pigments was highest under supplement of UV A+B radiation, while the combination of Cd or Ni and UV A+B caused further decrease. Thus, it could be shown that the combined treatment of UV A+B and Cd or Ni was antagonistic on UV-screening pigments. The combined sterss of UV A+B radiation an Cd or Ni also resulted in a reduction of peroxidase and catalase activity, while H 2 O 2 level and anthocyanin content were increased in Pisum sativum plant. The data showed that in some measured parameters there was a UV A+B and Cd or Ni synergistic effect, while with other parameters an antagonistic action was observed.

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Abstract  

Composting technologies rely on standard methods for quality determination. The maturity of a compost is assayed by self-heating experiments in Dewar-vessels. The resulting maximum temperature is classified on a five-level scale. This study demonstrated systematic errors that might occur when assays are performed in Dewars of different size. The vessels were characterized as heat conduction calorimeters and the processes of biochemical decomposition and heat generation and autothermic effects (temperature) were evaluated quantitatively.

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Abstract  

Microcalorimeters to monitor the heat dissipation of bench-scale animal cell cultures on line and in real time require a continuous circuit between the vessel measuring heat flow rate and the bioreactor. The modifications to the transmission lines and calorimetric heat exchanger were to: (i) reverse the usual upward direction of the cell suspension in the flow vessel to downwards; (ii) install an in situ washing/cleaning facility; (iii) use low diffusivity PEEK material; and (iv) maintain thermal equilibration by water-jacketing the transmission tubing. Chemical calibration showed that there was more than a 20% difference between the physical volume and the effective thermal volume. An appropriate thermodynamic system was defined in order to permit enthalpy balance studies.

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effective method to evaluate the metabolic activity of bacteria and investigate the effect of drugs and bacteria. While, conventional bacteriological technique, for example, agar diluted method [ 8 , 9 ], according to the size of inhibition zone on agar

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