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Ammonium Oxidation (ammonium + oxidation)
Selected AbstractsElevated atmospheric CO2 affects soil microbial diversity associated with trembling aspenENVIRONMENTAL MICROBIOLOGY, Issue 4 2008Celine Lesaulnier Summary The effects of elevated atmospheric CO2 (560 p.p.m.) and subsequent plant responses on the soil microbial community composition associated with trembling aspen was assessed through the classification of 6996 complete ribosomal DNA sequences amplified from the Rhinelander WI free-air CO2 and O3 enrichment (FACE) experiments microbial community metagenome. This in-depth comparative analysis provides an unprecedented, detailed and deep branching profile of population changes incurred as a response to this environmental perturbation. Total bacterial and eukaryotic abundance does not change; however, an increase in heterotrophic decomposers and ectomycorrhizal fungi is observed. Nitrate reducers of the domain bacteria and archaea, of the phylum Crenarchaea, potentially implicated in ammonium oxidation, significantly decreased with elevated CO2. These changes in soil biota are evidence for altered interactions between trembling aspen and the microorganisms in its surrounding soil, and support the theory that greater plant detritus production under elevated CO2 significantly alters soil microbial community composition. [source] Molecular characterization of microbial community in nitrate-removing activated sludgeFEMS MICROBIOLOGY ECOLOGY, Issue 2 2002Han-Woong Lee Abstract The microbial community composition and dominant denitrifying populations in high-nitrate-removing (CR-I) and low-nitrate-removing (CR-II) activated sludge from continuous bioreactors were investigated with most probable number (MPN) enumeration, fluorescence in situ hybridization (FISH) and 16S rDNA characterization. MPNs of nitrate-reducing bacteria of sludge CR-I and sludge CR-II were 2.82×107 and 2.69×104 colony-forming units ml,1, respectively. Eight denitrifying bacteria and two nitrate-reducing bacteria were isolated from sludge CR-I, and four denitrifying bacteria and three nitrate-reducing bacteria from sludge CR-II. Small subunit rDNA characterization of the isolates showed that the majority belonged to the genus Pseudomonas. By using FISH up to 76% (CR-I) and 52% (CR-II) of total 4,6-diamidino-2-phenylindole cell counts hybridized to the bacterial probe EUB338. Members of ,-Proteobacteria were the most abundant proteobacterial group in both sludges, accounting for up to 41.6% and 37.1% of those detected by EUB338, respectively, whereas a higher number of Cytophaga,Flexibacter cluster members were observed in CR-I sludge compared to CR-II sludge. In contrast with culture-based results, the numbers of rRNA group I Pseudomonads accounted for less than 0.01% of those detected by EUB338 in both sludges. Ribosomal DNA clone library analysis showed that the ,-Proteobacteria were also dominant in both sludges. In CR-I sludge, they were related to Zooglorea ramigera, Alcaligenes defragrans, denitrifying Fe-oxidizing bacteria and Dechlorimonas sp., whereas in CR-II sludge, they were related to Nitrosomonas sp. and Dechlorimonas agitatus. When this reactor was operated under anaerobic and anoxic conditions, nitrifying bacteria could adapt to the anoxic environment. We inferred that anaerobic ammonium oxidation and nitrite oxidation may occur in low-nitrate-removing sludge CR-II and inhibit denitrification. [source] Experimental determination of Anammox decay coefficientJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2009D. Scaglione Abstract This paper describes an experimental method used to evaluate the anaerobic ammonium oxidation (Anammox) decay coefficient by means of a batch test. The test was carried out using an experimental procedure based on manometric measurements of the dinitrogen gas that is produced by the Anammox process. The accuracy of the procedure had previously been assessed, and the method was used to determine the specific Anammox activity (SAA mg N2 -N g VSS,1 d,1,) and the maximum nitrogen production rate (MNPR, NmL N2 L,1 d,1) under several different conditions. A specific batch test, which lasted for 148 days, was performed to assess the decay coefficient. The activity decrease was monitored and the estimated value of the decay coefficient was found to be 0.0048 d,1 at 35 °C, for which the corresponding half-life time of the Anammox biomass was 145 days. This value is higher than other values reported in the literature, but in accordance with the slow growth rate of the Anammox bacteria. Copyright © 2009 Society of Chemical Industry [source] Autotrophic nitrification and denitrification characteristics of an upflow biological aerated filterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2001Dong-Woo Han Abstract Wastewater nitrification was carried out using a laboratory-scale upflow biological aerated filter (BAF) packed with a polyurethane-based porous medium. The filtration medium has macro-pores which provide a greater surface area for the development of biofilms. The macro-pores have both aerobic and anaerobic zones, depending on the depth of oxygen penetration in the medium. Wastewater ammonium was oxidized at a maximum rate of 1.8,kg NH4+m,3d,1 and showed more than 90% nitrification efficiency in the BAF. During the biological nitrification of wastewater, considerable nitrogen loss was observed in the BAF under oxygen-limited conditions when organic carbons were not provided for denitrification. Most probably, the lost nitrogen was converted to gaseous nitrogen compounds including dinitrogen by autotrophic dentrification and anaerobic ammonium oxidation. © 2001 Society of Chemical Industry [source] Comparison of quasisteady-state performance of the DEAMOX process under intermittent and continuous feeding and different nitrogen loading ratesBIOTECHNOLOGY JOURNAL, Issue 7 2007Sergey Kalyuzhnyi Professor Abstract The recently developed denitrifying ammonium oxidation (DEAMOX) process combines the anammox reaction with autotrophic denitrifying conditions using sulfide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. This paper compares a quasisteady-state performance of this process for treatment of baker's yeast wastewater under intermittent and continuous feeding and increasing nitrogen loading rate (NLR) from 300 till 858 mg N/L/d. The average total nitrogen removal slightly decreased on increasing the NLR: from 86 to 79% (intermittent feeding) and from 87 to 84% (continuous feeding). The better performance under continuous feeding was due to a more complete nitrate removal in the former case whereas the ammonia removal was similar for both feeding regimes under the comparable NLR. A possible explanation can be that, during continuous feeding (simultaneous supply of nitrate and sulfide), there were less mass transfer limitations for sulfide oxidizing denitrifiers presumably located in the outer layer of sludge aggregates. On the contrary, the ammonia oxidisers presumably located inside the aggregates apparently suffered from nitrite mass transfer limitations under both the feedings. The paper further describes some characteristics of the DEAMOX sludge. [source] | ||||||||||