Mar 26, Abstract Voltametric degradation of phenol was carried out at microbial electrode. This electrode is based on graphite carbon and natural phosphate modified by bacteria inserted in the phosphate matrix, the whole is covered by a polymer developed in situ on the surface. This electrode, designated subsequently by bacteria-NP-CPE, Showed stable response and was characterized with voltametric methods, as cyclic voltammetry CV and electrochemical impedance spectroscopy EIS.
China Nitrogenous fertilizers are generally thought to have an important role in regulating methane oxidation. Phylogenetic analysis of pmoA genes showed that nitrogen fertilization resulted in apparent changes in the community composition of methane-oxidizing bacteria MOB.
Furthermore, although no statistically significant relationship was observed between pmoA gene and amoA gene abundances, methane oxidation activity was significantly negatively correlated with nitrification activity in the presence of urea or ammonium sulfate.
Our results indicate that the methane oxidation activity in paddy soils might be inhibited when the concentration of ammonium fertilizers is high and that the interactions between ammonia and methane oxidizers need to be further investigated.
Introduction Methane CH4a potent greenhouse gas GHGis involved in a number of chemical and physical processes in the earth's atmosphere, including global warming Crutzen, Despite a short residence time in the atmosphere 10 yearsthe ability of CH4 to absorb infrared radiation is 20—30 times greater than that of CO2 Rodhe, During most of the last years, atmospheric CH4 has increased monotonically.
However, even though the CH4 concentration in the atmosphere became erratic and did not increase overall from untilit has begun to increase again Rigby et al. CH4, which is produced in the soil, enters the roots of the rice plants and is transported through the gas vascular system of the plants to the atmosphere, and oxygen is transported from the atmosphere into the roots.
Thus, rice roots are partially oxic, which allows methane-oxidizing bacteria MOB to be active in the rhizosphere Conrad, MOB associated with the rhizosphere of rice plants oxidize CH4 aerobically and use it as a source of carbon and energy.
The increasing demand for rice has led to the intensified application of nitrogenous fertilizers, which may affect CH4 oxidation because MOB are generally thought to be inhibited by ammonium-based fertilizers, as has been demonstrated for soils Steudler et al. This mechanism is believed to be responsible for the inhibition of CH4 uptake in soils exposed to high concentrations of available N Hanson and Hanson, In contrast, numerous studies have demonstrated that the activity and growth of MOB in the root zone of rice plants are stimulated upon fertilization Bodelier et al.
It is noteworthy to mention that some studies have also demonstrated no effects of ammonium-based N-fertilization on MOB Dunfield et al. Even though the effects of nitrogenous fertilizers on CH4 oxidation have been the most investigated regulating factor of aerobic CH4 oxidation reviewed in Bodelier and Laanbroek, ; Aronson and Helliker,it is obvious that the interactions between the nitrogen and methane cycle are complex and far from completely understood Bodelier, Therefore, microcosm incubations were performed to investigate the effects of urea and ammonium sulfate on methane oxidation in a paddy field to better understand the interactions between the methanotrophic community and ammonia-oxidizing prokaryotes.
The paddy soil was developed from lake sediment and is classified as a Typic Haplanthrept based on U. A full description of this long-term fertilization experiment and its management regimes has been previously described Wu et al.
A rice—wheat rotation system was maintained in the field, and soil sampling was performed from triplicate plots that received chemical fertilizers NPK during the rice-growing season. Bulk soil top 0—5 cm was collected and transported on ice to the laboratory immediately after sampling.
All soil microcosms contained slurries with a final volume of 50 ml through the addition of sterile distilled water. The treatments were then renewed after 0, 4, 8, 12, 16, 20, and 24 days of incubation, providing the targeted concentrations of CH4 and nitrogenous fertilizers described above.
Gas samples were collected to determine the CH4 concentration in the headspace of the microcosms. Before gas samplings, the bottles were gently shaken by hand for 1 min to release the CH4 dissolved in the submerged water layer into the headspace.
One milliliter of the gas sample in the headspace was analyzed using gas chromatography with a flame ionization detector, as described previously Liu et al. Soil slurries were collected after 0, 15, and 27 days of incubation.
Before sampling, the bottles were vigorously shaken by hand; 10 ml of the slurries were transferred to centrifuge tubes and then centrifuged at 10, rpm for 5 min to collect the soil pellets. A dilution series of a standard template across six orders of magnitude 3.
The blank was always run with water as the template instead of the soil DNA extract. The PCR conditions used for the archaeal and bacterial amoA genes were the same as previously described Jia and Conrad, For the pmoA gene amplification, the PCR conditions were as follows: PCR amplification efficiencies of The specific amplifications of amoA and pmoA were also determined using a melting curve analysis, which always resulted in a single peak.
The PCR products were run in a 1. The cloning was performed following the same procedure as described above. At least 6—12 clones were randomly selected for each treatment. Statistics Spearman's correlation analyses were performed to assess the relationships among methane oxidation activity, nitrification activity and the abundance of the MOB SPSS The methane concentrations were 1.
A significantly higher CH4 concentration of Feb 13, · Effects of pH and Oxygen and Ammonium Concentrations on the Community Structure of Nitrifying Bacteria from Wastewater Alenka Prinčič, 1, 2, * Ivan Mahne, 1 France Megušar, 1 Eldor A. Paul, 2 and James M. Tiedje 2. Biological Corrosion Failures Thomas R.
Jack, NOVA Chemicals Ltd. − 0 0 4 8 pH 12 16 Oxidation reduction potential (E h) Secondary effects can also be important. These include such things stiﬂe the rate of metal oxidation, and limit the overall rate . Nov 12, · The ANAMMOX bacteria are known to anabolize CO 2 taking advantage of energy generated from oxidation of nitrite to nitrate (Fig.
(Fig.2). 2). Both stable carbon isotopic fractionation and genome detection proved that inorganic carbon was fixed through the acetyl-CoA pathway (Schouten et al., ; Strous et al., ).
The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. ( ± ) agreed well with partial (±50%) oxidation of propionate. The highest rate of propionate oxidation measured in the The present study describes the effects of organic compounds on anaerobic ammonium-oxidizing bacteria. The. The physical property that has by far the greatest effect on the rate of S o oxidation is particle size. The finer the particle size, the larger the surface area exposed to soil microorganisms and the more rapid the oxidation process. Table 1 clearly shows this effect of particle size. ferrooxidans at 15, 25 and 35 oC and maximum bacterial activity, thus maximum oxidation rate, was reached at 35 oC. At this temperature, the lag phase, the adaptation period of the bacteria, was very short and oxidation started.
Ursodeoxycholic acid is a bile acid that is produced by bacterial oxidation of chenodeoxycholic acid, and is the only effective treatment.
It retards progression of the disease possibly by reducing apoptosis of hepatocytes and suppression of the cytotoxic effects of other bile acids. The physical property that has by far the greatest effect on the rate of S o oxidation is particle size.
The finer the particle size, the larger the surface area exposed to soil microorganisms and the more rapid the oxidation process.
Table 1 clearly shows this effect of particle size. Nitrogenous fertilizers are generally thought to have an important role in regulating methane oxidation.
In this study, the effect of ammonium on methane oxidation activity was investigated in a paddy soil using urea at concentrations of 0, 50, , and μg N per gram dry weight soil (N/g.d.w.s) and ammonium sulfate at concentrations of 0, 50 and μg N/g.d.w.s.