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| Titel |
The effect of nitrate addition on abundance of nirK, nirS and gln genes in acidified Norway spruce forest soil |
| VerfasserIn |
Jiří Bárta, Karolina Tahovská, Jiri Kana, Hana Šantrůčková |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040675
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| Zusammenfassung |
| The denitrification is the main biotic process leading to loses of fixed nitrogen as well as
removal of excess of nitrate (NO3-) from the soil environment. The reduction of NO2- to
nitric oxide (NO) distinguishes the “true” denitrifiers from other nitrate-respiring bacteria.
This reaction is catalyzed by two different types of nitrite reductases, either a cytochrome cd1
encoded by nirS gene (nirS denitrifiers) or a Cu-containing enzyme encoded by nirK gene
(nirK denitrifiers). The nirS denitrifiers are located mostly in rhizosphere, while the nirK
denitrifiers are more abundant in bulk soil. These two groups can be also classified as markers
of denitrification.
Glutamine synthetase is one of the main bacterial NH4+ assimilating enzymes; it is coded
by glnI gene. Glutamine synthetase is mostly active when N is the limiting factor for bacterial
growth. There is recent evidence that the activity may be affected by the presence of
alternative N source (i.e. NO3-). However, in anaerobic condition NO3- can be
used also by the denitrifying bacteria so there may be strong competition for this
nutrient.
The laboratory experiment was performed to evaluate the effect of nitrates (NO3-)
on abundance of nirK, nirS and gln gene copy numbers. The amount of NO3-
corresponded to the actual atmospheric depositions on experimental sites in the
Bohemian Forest. Litter organic layer (0-5cm of soil) was used for laboratory incubation
experiment. Four replicates of control (no addition of NO3-), and NO3-addition were
incubated anaerobically for one month. After the incubation DNA was extracted and the
number of nirK, nirS and gln gene copies was determined using qPCR (SYBRGreen
methodology). Results showed that the addition of NO3- significantly increased
the number of nirK and nirS denitrifiers from 5.9x106 to 1.1x107 and from not
detectable amount to 1.4x106, respectively. The gln gene copy number was also
higher after NO3-addition. However, the difference was not statistically significant. |
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