Population Ecology of Nitrifying Bacteria

Belser, L. W.

doi:10.1146/annurev.mi.33.100179.001521

Cited by 404 publications

(202 citation statements)

References 41 publications

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“…Only a few compounds-phenyl, methyl, or hydroxyethyl hydrazine and hydrogen peroxide-are known to inhibit the HAO enzymatic pathway in Nitrosomonas (34). Most commercial nitrification inhibitors (such as dicyandiamide or nitrapyrin) suppress nitrifier activity by targeting primarily the AMO pathway; thus, they could be vulnerable to genetic changes in nitrifier populations or to natural genetic diversity in ammonia-oxidizers (AOs) (35,36). Given the inherent genetic variability in nitrifier populations (35), it is likely that BNIs released from Brachiaria spp.…”

Section: Resultsmentioning

confidence: 99%

Evidence for biological nitrification inhibition inBrachiariapastures

Subbarao

Nakahara²,

Hurtado³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

427

420

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Nitrification, a key process in the global nitrogen cycle that generates nitrate through microbial activity, may enhance losses of fertilizer nitrogen by leaching and denitrification. Certain plants can suppress soil-nitrification by releasing inhibitors from roots, a phenomenon termed biological nitrification inhibition (BNI). Here, we report the discovery of an effective nitrification inhibitor in the root-exudates of the tropical forage grass Brachiaria humidicola (Rendle) Schweick. Named ''brachialactone,'' this inhibitor is a recently discovered cyclic diterpene with a unique 5-8-5-membered ring system and a ␥-lactone ring. It contributed 60 -90% of the inhibitory activity released from the roots of this tropical grass. Unlike nitrapyrin (a synthetic nitrification inhibitor), which affects only the ammonia monooxygenase (AMO) pathway, brachialactone appears to block both AMO and hydroxylamine oxidoreductase enzymatic pathways in Nitrosomonas. global warming ͉ nitrogen pollution ͉ nitrous oxide emissions ͉ root exudation ͉ climate change M ost modern agricultural systems are based on large inputs of inorganic nitrogen (N), with ammonium (NH 4 ϩ ) being the primary N source (1, 2). Also, current crop management practices result in the development of highly nitrifying soil environments (3, 4). Nitrification results in the transformation of the relatively immobile NH 4 ϩ to highly mobile nitrate (NO 3 Ϫ ), making inorganic N susceptible to losses through leaching of NO 3 Ϫ and/or gaseous N emissions, potentially initiating a cascade of environmental and health problems (1, 2, 5, 6). Nitrous oxide (N 2 O) is one of the three major biogenic greenhouse gases contributing to global warming, produced primarily from denitrification processes in agricultural systems (5, 7). Also, assimilation of NO 3 Ϫ by plants can result in further N 2 O emissions directly from plant canopies (8). The low agronomic N-use efficiency (NUE) found in many agricultural systems is largely the result of N losses associated with nitrification (i.e., N losses from NO 3 Ϫ leaching and denitrification) (9-11). Most plants have the ability to assimilate both NH 4 ϩ and NO 3 Ϫ (12); therefore, nitrification does not need to be a dominant process in the N cycle for efficient N use.Nitrification is low in some forest and grassland soils (13-17). Since the early 1960s, some tropical grasses have been suspected of having the capacity to inhibit nitrification (18-21). However, this concept remained controversial due to the lack of direct evidence showing such inhibitory effects or the identification of specific inhibitors (22).We adopted a very sensitive bioassay using a recombinant luminescent Nitrosomonas europaea to detect biological nitrification inhibition (BNI) in plant-soil systems with the inhibitory activity of roots expressed in allylthiourea units (ATU) (23). Using this methodology, we were able to show that certain plants release nitrification inhibitors from their roots (23-26). Such BNI capacity appears to be relatively widespread among...

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Section: Resultsmentioning

confidence: 99%

Evidence for biological nitrification inhibition inBrachiariapastures

Subbarao

Nakahara²,

Hurtado³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

427

420

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“…Elevated soil moisture has been reported to alter AOB abundance both positively and negatively. Relatively moderate elevation of soil moisture can increase abundance by reducing water stress (29,30); larger increases in soil moisture can depress abundance by Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

Ammonia-oxidizing bacteria respond to multifactorial global change

Horz

Barbrook

Field

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

275

226

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Recent studies have demonstrated that multiple co-occurring global changes can alter the abundance, diversity, and productivity of plant communities. Belowground processes, often mediated by soil microorganisms, are central to the response of these communities to global change. Very little is known, however, about the effects of multiple global changes on microbial communities. We examined the response of ammonia-oxidizing bacteria (AOB), microorganisms that mediate the transformation of ammonium into nitrite, to simultaneous increases in atmospheric CO 2, precipitation, temperature, and nitrogen deposition, manipulated on the ecosystem level in a California grassland. Both the community structure and abundance of AOB responded to these simulated global changes. Increased nitrogen deposition significantly altered the structure of the ammonia-oxidizing community, consistently shifting the community toward dominance by bacteria most closely related to Nitrosospira sp. 2. This shift was most pronounced when temperature and precipitation were not increased. Total abundance of AOB significantly decreased in response to increased atmospheric CO 2. This decrease was most pronounced when precipitation was also increased. Shifts in community composition were associated with increases in nitrification, but changes in abundance were not. These results demonstrate that microbial communities can be consistently altered by global changes and that these changes can have implications for ecosystem function.

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“…The chemolithoautotrophic oxidation of ammonia to NO 2 − is in many ecosystems limited by the availabil-ity of ammonia (Belser 1979). Quantitatively, AOA is highly active at 0.14 mM (2.53 mg l −1 ) and 0.79 mM (14.25 mg l −1 ) NH 4 + (Hatzenpichler et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Adverse Effects of Ammonia on Nitrification Process: the Case of Chinese Shallow Freshwater Lakes

Chen

Cao

Song

et al. 2009

Water Air Soil Pollut

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Nitrification is a process in which ammonia is oxidized to nitrite (NO 2 − ) that is further oxidized to nitrate (NO 3 − ). The relations between these two steps and ambient ammonia concentrations were studied in surface water of Chinese shallow lakes with different trophic status. For the oxidations of both ammonia and NO 2 − , more eutrophic lakes generally showed significantly higher potential and actual rates, which was linked with excessive ammonia concentrations. Additionally, both potential and actual rates for ammonia oxidation were higher than those for NO 2 − oxidation in the more eutrophic lakes, while in the lakes with lower trophic status, both potential and actual rates for ammonia oxidation were almost equivalent to those for NO 2 − oxidation. This can be explained by the excessive unionized ammonia (NH 3 ) concentration that inhibits nitrite-oxidizing bacteria in the more eutrophic lakes. The laboratory experiment with different ammonia concentrations, using the surface water in a eutrophic lake, showed that ammonia oxidation rates were proportional to the ammonia concentrations, but NO 2 − oxidation rates did not increase in parallel. Furthermore, NO 2 − oxidation was less associated with particles in natural water of the studied lakes. Without effective protection, it would be selectively inhibited by the excessive ammonia in hypereutrophic lakes, resulting in NO 2 − accumulation.Shortly, the increased concentrations of ammonia cause a misbalance between the NO 2 − -producing and the NO 2 − -consuming processes, thereby exacerbating the lake eutrophication.

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Population Ecology of Nitrifying Bacteria

Cited by 404 publications

References 41 publications

Evidence for biological nitrification inhibition inBrachiariapastures

Evidence for biological nitrification inhibition inBrachiariapastures

Ammonia-oxidizing bacteria respond to multifactorial global change

Adverse Effects of Ammonia on Nitrification Process: the Case of Chinese Shallow Freshwater Lakes

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