Activity Of Nitrifying Bacteria Research Articles

The effect of increasing application rate of granular calcium ammonium nitrate on net nitrification in a laboratory study of grassland soils

Soil incubation studies were undertaken in controlled environment cabinets at 15°C to investigate the effect of increasing application rates of calcium ammonium nitrate (CAN) on net nitrification in two grassland soils. Granular CAN was applied to the surface of freshly collected, moist soil, at a rate equivalent to 0, 100, 200, 400, 800 and 1600µg NH 4 + -N and NO 3 - -N per gram of oven dry soil. In half the treatments finely ground CaCO3 was incorporated into the moist soil to raise the starting pH. Changes in soil mineral N and pH were measured at weekly intervals up to six-weeks. The most probable number (MPN) technique was used to enumerate the NH 4 + -N and NO 2 - -N oxidizers at the beginning and end of the incubation. At low rates of CAN application there was considerable NH 4 + -N oxidation to NO 3 - -N during the incubation of both soils. Lime stimulated this N transformation. At high application rates (i.e. 800 and 1600 ppm) there was little change in NH 4 + -N or NO 3 - -N on either soil during the 6 week incubation, in the presence or absence of lime. The rate of NO 3 - -N produced peaked at 5.6 and 3.8 mg NO 3 - -N kg−1 d−1 on soil 1 and 2 respectively, in the presence of lime. Above a level of 400 ppm CAN (equivalent to 38 kg N ha−1) the rate of NO 3 - -N produced decreased. The higher rate of net nitrification in soil 1 compared with soil 2 was probably due to a higher number of nitrifying bacteria. Although high rates of CAN decreased the nitrifying activity of both soils there was little difference between treatments in the actual numbers of NH 4 + -N and NO 2 - -N oxidizers determined by the MPN technique. The results showed that the rate of granular CAN applied to the soil surface can influence the local activity of nitrifying bacteria and subsequent N transformations. At application rates of CAN generally used agriculturally for grass production, it is likely that net nitrification of the NH 4 + -N in the fertilizer granule will be inhibited.

Temperature effect on nitrifying bacteria activity in biofilters: activation and free ammonia inhibition

Nitrifying bacteria activity and concentrations depend on specific free ammonia concentration (ratio NH3/biomass), that is a function of temperature, pH, ammonium concentration and nitrifying biomass concentration. So, temperature is a key parameter in the nitrification process producing two opposite effects: bacteria activation and free ammonia inhibition. These phenomena are studied in an up-flow biological aerated filter (UBAF) settled by a nitrifying biofilm (measured as Volatile Attached Solids, VAS). The plug flow allows to disclosure of both effects, activation and inhibition. For Nitrosomonas bacteria only an activation effect was observed; their activity reaches a maximum at 28-29 °C. For Nitrobacter the free ammonia inhibition prevails against the activation effect for values greater than 1 mg N-NH3/mg VAS allowing nitrite accumulation of 80%; this inhibition threshold value for nitrifying biofilm is obtained measuring the specific rate of utilization of substratum per unit of biomass (μmax/Y) by activity test. The knowledge of this threshold in a biofilm process is fundamental in order to control the nitrite accumulation in nitrifying biofilm reactors.

Effects of urea fertilization and liming on nitrification in cerrados soils (Brazil)

Abstract Nitrification is a microbiological process involved in the production of nitrate, which is important from the agricultural and environmental view points due to its mobility in soil. Also, in this form it is easily reduced by the denitrifying bacteria to gases which are released from the soil. Nitrification in soil is controlled by several environmental factors such as pH, mineral nutrition, temperature, and moisture (Haynes 1986). Nitrification has been found to be minimal at a pH value below 5.0 (Dancer et al. 1973; Gilmour 1984). However, nitrification can occur in some acid soils at a pH value below 4.5 (Weber and Gainey 1962; Weier and Gilliam 1986). Although nitrification in acid soils may be associated with the activity of autotrophic nitrifying bacteria (Hankinson and Schmidt 1988; Hayatsu 1993), heterotrophic microorganisms may also be involved in the nitrification process (Schimel et al. 1984; Stroo et al. 1986). In the Cerrados soils that are strongly acidic, information about the microorganisms involved in nitrification is limited.

Immobilization of nitrifying bacteria in porous pellets of urethane gel for removal of ammonium nitrogen from waste-water

The effects of immobilizing materials on the activity of nitrifying bacteria and removal of ammonium nitrogen (NH4-N) from waste-water by immobilized nitrifying bacteria were investigated using six urethane prepolymers. With a urethane prepolymer containing 2.27% free isocyanate, a high activity yield of nitrifying bacteria was obtained. There was a drastic improvement over the conventional method of immobilization by acrylamide in the activity yield. Inorganic synthetic waste-water was treated at a high loading rate of 0.24 kg N·m−3·day−1. The NH4-N concentration of the effluent could be reduced to 2 mg·1−1 or less and the removal was 90%. The life of the pellets in terms of activity was at least 120 days.

Immobilization of nitrifying bacteria by polyethylene glycol prepolymer

Abstract The effects of immobilizing materials on the activity of nitrifying bacteria were investigated by using 11 kinds of prepolymers of polyethylene glycol. Relative respiratory activity of immobilized nitrifying bacteria with polyethylene glycol metacrylate prepolymer was higher than that of polyethylene glycol acrylate prepolymer, and there was a tendency for relative respiratory activity to be higher with a prepolymer of greater molecular weight. With the polyethylene glycol prepolymer, there was a drastic improvement over the conventional method of immobilization by acrylamide in the relative respiratory activity of the pellet. Inorganic synthetic wastewater was treated under a high loading rate of 1.14 kg-N/m 3 ·d. Influent NH 4 -N could be removed to 2 mg/ l or less and the nitrogen removal was 90%.

Short term nitrogen dynamics in a small Brazilian wetland (Lago Infernão, São Paulo)

ABSTRACTWe have studied a number of related processes of the nitrogen cycle in a Brazilian floodplain lake to identify the major pools and pathways over a short time period. The study was centred on the littoral zone dominated by the floating plantEichhornia azurea, which has a large epiphyte algal community of which heterocystous cyanobacteria were the major components. The water column was continuously undersaturated with oxygen although some elevated values (to 60% saturation) were recorded in the macrophyte beds in the afternoon. Marked diel temperature changes were documented. NH4-N dominated the dissolved N component in the water with maximal values (60 mg m−3) at lowest O2, concentrations early in the morning. Nitrogen fixation (acetylene reduction) of the epiphyte community showed marked diel changes with daily values of 5 mg N fixed m−2day−1(based on 3:1 C2H4:N2ratio). Macrophyte NH4-N uptake rates (in situincubations) were 93 mg N m−2day−1. The activities of nitrifying bacteria could not be detected with the nitrapyrin block on dark CO2fixation but denitrification (acetylene block technique) was recorded in the sediments when enhanced with NO-3. The major pathways of aquatic nitrogen involved macrophyte uptake and sediment release of NH4-N.

EFFECT OF PHOSPHORUS LEVEL ON NITRIFICATION RATES IN THREE LOW-PHOSPHORUS ULTISOLS

Using perfusion and batch incubation, we determined minimum levels of inorganic phosphorus (P) required for maximum activity of nitrifying bacteria in soils. Three Pdeficient subsoil materials (Arenic Paleudult, Typic Paleudult, and Aquic Hapludult) were limed to approximately pH 7 and treated with various rates of P as KH2PO4 and Ca(H2PO4)2 to establish comparable P concentrations in perfusates and soil solutions. Ammonium sulfate and KNO2 were used as ammonium and nitrite substrates; an enriched inoculant was added to ensure an equal number of nitrifiers. We monitored nitrite, NO3-, pH, and P 2 d after the initiation of experiments and weekly thereafter. Nitrification at each P level was graphed as a function of time, to determine the effect of P on delay times and maximum nitrification rates. Inorganic P concentrations above which NH4+ oxidizers would not respond to additional P were 0.59 ± 0.24 μM for the minimum delay time and 0.60 ± 0.28 μM for the maximum nitrification rate. Nitrite oxidizers required no more than 0.13 and 0.24 ± 0.07 μM P for the minimum delay time and the maximum oxidation rate, respectively.

Removal of nitrogen from industrial wastewaters with the use of algal rotating disks and denitrification packed bed reactor

An attempt was made to use an algal rotating disk system in a two-step biological purification of nitrogen fertilizer industry wastewaters. The proposed method involved the removal of ammonium by Stichococcus bacillaris growing on the rotating disk and of oxidized forms of nitrogen by denitrifying bacteria. The use of a rotating algal disk followed by denitrification bed as the second step of biological treatment removed about 90% of nitrogen from the wastewater. A change of purification sequence resulted in the appearance of NO − 3 and NO − 2 in the purified wastewater caused by the activity of nitrifying bacteria accompanying algae in the biological film on the disk. It was found that methanol used as a carbon source for denitrifying bacteria could be replaced by organic matter of algal origin.

Population Ecology of Nitrifiers in a Stream Receiving Geothermal Inputs of Ammonium

The distribution, activity, and generic diversity of nitrifying bacteria in a stream receiving geothermal inputs of ammonium were studied. The high estimated rates of benthic nitrate flux (33 to 75 mg of N . m . h) were a result of the activity of nitrifiers located in the sediment. Nitrifying potentials and ammonium oxidizer most probable numbers in the sediments were at least one order of magnitude higher than those in the waters. Nitrifiers in the oxygenated surface (0 to 2 cm) sediments were limited by suboptimal temperature, pH, and substrate level. Nitrifiers in deep (nonsurface) oxygenated sediments did not contribute significantly to the changes measured in the levels of inorganic nitrogen species in the overlying waters and presumably derived their ammonium supply from ammonification within the sediment. Ammonium-oxidizing isolates obtained by a most-probable number nonenrichment procedure were species of either Nitrosospira or Nitrosomonas, whereas all those obtained by an enrichment procedure (i.e., selective culture) were Nitrosomonas spp. The efficiency of the most-probable-number method for enumerating ammonium oxidizers was calculated to be between 0.05 and 2.0%, suggesting that measurements of nitrifying potentials provide a better estimate of nitrifying populations.

Seasonal distribution of nitrifying bacteria and rates of nitrification in coastal marine sediments

The distribution of nitrification potential (NP) with depth in sediment and season was investigated in a shallow sandy sediment (0.5 m water) and a deeper muddy sediment (17m water). In both sediments, nitrifying bacteria were present in the anoxic strata (oxygen penetration was 5 mm below the surface). The NP at 6-8 cm depth in the sediment was 50% and 10% of the surface NP at the sandy and muddy sediment, respectively. It is suggested that bioturbation and physical disturbance of the sediment were the most likely reasons for this distribution. The NP increased as sediment temperature decreased. This effect was less marked in the muddy sediment. It is concluded that during the summer, the numbers or specific activity of nitrifying bacteria diminished for the following reasons: There was decreased O2 penetration into the sediment and increased competition for O2 by heterotrophs; there was increased competition for NH4 (+) and there was inhibition by H2S. These effects counteracted the potentially higher growth rates and increased rates of NH4 (+) production at the elevated summer temperatures. The potential nitrification rates in the upper 1 cm, which were measured at 22°C, were converted to calculated rates at the in situ temperature (Q10=2.5) and in situ oxygen penetration. These calculated rates were shown to closely resemble the measured in situ rates of nitrification. The relationship between the in situ rates of nitrification and the nitrification potential is discussed.

Primary production under the Ross Ice Shelf, Antarctica1

Primary production, defined as fixation of [14C]bicarbonate, occurs in the waters under the Ross Ice Shelf, Antarctica. About 1.5 g C·m−2 is fixed annually. This amount is sufficient to support the observed macrofaunal population and may be due to the activity of chemoautotrophic nitrifying bacteria.

Nitrogen conservation in a tropical rain forest.

A series of plots in an Amazonian Rain Forest were trenched and treated with calcium to determine the effects of perturbation on numbers and activity of nitrifying bacteria. Although treatment resulted in between 2 and 26% of the nitrogen being lost from the humus layer, virtually all of it was in the NH 4+ form. Numbers of nitrifying bacteria in the plots were relatively low. The low numbers and low activity of nitrifying bacteria is attributed to the low pH and high concentration of tannins in the root mat. It is hypothesized that the suppression of nitrifying bacteria results in nitrogen conservation in the rain forest.

Evaluation of nitrifying activity in sediments by dark 14C-bicarbonate incorporation

A method has been developed for measuring the activity of nitrifying bacteria in sediment samples within very short incubation times (a few hours). Biological dark 14C-bicarbonate incorporation is measured with and without addition of 5 mg 1−1 N-serve, a substance which was proved to be a specific inhibitor of autotrophic CO2-fixation by nitrifying bacteria. The value of N-serve sensitive bicarbonate incorporation can be quantitatively related to the rate of nitrogen oxidation by autotrophic nitrifiers.First application of this method on marine sediments gives results in good agreement with information provided by other methods. Nitrification rates in the range 0–20 μmole nitrogen oxidized per dm3 sediment and per hour are found in the upper cm of the sediments of the coastal regions of the Southern Bight of the North Sea.

Vertical distribution of nitrate concentration in interstitial water of marine sediments with nitrification and denitrification

Vertical concentration profiles of nitrate and nitrite in interstitial water of sediment in the Sluice Dock at Ostend (Belgium) commonly show a maximum in nitrate concentration at a few centimeters depth where sediments are sandy and poor in organic matter, while in muddy and organic‐rich sediments, nitrate is lower in interstitial water than in the overlying water and decreases rapidly with depth. Direct measurements of the activity of autotrophic nitrifying bacteria in the sediments show nitrification in the upper few centimeters of sandy sediments but not in muddy sediments.A mathematical model is proposed to analyze quantitatively these experimental results, taking into account nitrification, denitrification, diffusion, and sedimentation. Seasonal variations of nitrate concentration in overlying water are slow enough to justify the use of a stationary (steady state) model. When appropriate values are used for the parameters (rate of nitrification, depth of the sedimentary layer in which nitrification occurs, rate of denitrification, diffusion coefficient), some being experimentally determined, the model predicts concentration profiles in good agreement with experimental data.

The distribution of nitrifying bacteria in soil aggregates

Abstract The special arrangement of soil particles composing aggregates is known to give some influences on nitrifying bacteria in soil. Greenwood (962) (1) showed that the activity of nitrifying bacteria in an aggregate is limited by the diffusion of oxygen into it through its pores. He pointed out the possibility of the co-existence of 2 zones of the entirely different characters in an aggregate, i. e., an aerobic zone, only in which nitrifying bacteria are able to be active, and an anaerobic zone. Neither he nor SEIFERT (1964) (2), who made a similar discussion to Greenwood's, however, made further examination in the distribution of nitrifying bacteria in an aggregate. Both of them assumed the distribution of nitrifying bacteria as homogenous in all parts of an aggregate.

Nitrification of ammoniacal fertilizers in some California soils

Because of the manner in which ammonium fertilizers are applied and the tendency of the ammonium ion as well as of free ammonia to be absorbed at the point of contact with soil colloids, localized high concentrations are the rule rather than the exception. A concentration gradient is produced with a maximum along the line of application. In experiments intended to simulate a cross section of a fertilizer band, it was shown that nitrification is rapid and complete at low ammonium concentrations such as would occur at the edge of a band. At higher concentrations, inhibition of nitrification may result from one or more causes: (1) excessively high pH resulting from application of alkaline materials; (2) excessively low pH resulting from formation of nitrous and nitric acids; (3) presence of free ammonia, exerting selective inhibition on the nitrate-forming bacteria; (4) salt effect, resulting in osmotic concentrations too high for optimal activity of nitrifying bacteria. The data of these experiments show that, under optimum conditions, nitrification is an extraordinarily rapid process. This fact should prove helpful in interpreting numerous field observations involving either response or lack of response to ammonium fertilizers. If moisture, pH, and temperature conditions of the soil are satisfactory, it may be assumed with confidence that nitrate will be produced from an added ammonium fertilizer in sufficient quantity to keep pace with the needs of growing plants in most agricultural soils.