|
|
Recognition of microbial patterns in earthworms
Škanta, František ; Bilej, Martin (advisor) ; Kopečný, Jan (referee) ; Šimek, Miloslav (referee)
Survival of earthworms in the environment depends on their ability to recognize and eliminate potential pathogens. Two closely related earthworm species Eisenia andrei and Eisenia fetida inhabit different environment with specific microbiota. Both species can be reliably determined using of species-specific primers for cytochrome c oxidase I (COI) and stringent PCR conditions. Whereas, we did not observed any substantial differences in the expression and activity of CCF and lysozyme upon microbial challenge, the expression as well as the hemolytic activity of fetidin/lysenins was considerably higher in E. andrei as compared to E. fetida. Genomic DNA analyses revealed significantly higher level of fetidin/lysenins in E. andrei compared to E. fetida suggesting hypothetical gene duplication. Earthworms live in permanent close contact with microbial environment. Coelom cavity as well as the gut of E. andrei earthvworm differs in the number of bacteria. The number of bacteria in the gut is more than six time higher than in coelomic fluid. High microbial load of E. coli O55, B. subtilis W23, and S. cerevisiae S288 in the earthworm environment, resulted in an increase of microorganisms in both, the coelom and the gut. The changes in mRNA levels of defense molecules (pattern recognition receptors CCF,...
|
|
| |
|
|
N.sub.2./sub.O and N.sub.2./sub. emissions, denitrification activity and the size of the denitrifying community in a pasture soil – what is the role of pH?
Čuhel, Jiří ; Šimek, Miloslav ; Laughlin, R.J. ; Chéneby, D. ; Bru, D. ; Philippot, L.
Denitrification and subsequent N emissions are significantly influenced by soil pH. Nevertheless, it is not clear, whether pH controls denitrification only due to the influence on kinetics of denitrification enzymes or also due to the different structure of denitrifiers. The objective of the present study was to compare results from N gas emissions and N.sub.2./sub.O molar ratio from soils with artificially changed pH, with those obtained from potential denitrification, and to find out whether there is a relationship between N fluxes and abundance of denitrifiers. The experimental site was located in a grassland area at Borová Farm near Český Krumlov, Czech Republic, and consisted of 12 plots (3x3 m) amended with KOH solution (pH alkaline), H.sub.2./sub.SO.sub.4./sub. solution (pH acidic) or with no amendments (pH natural). The .sup.15./sup.N gas flux method was used to quantify emissions of N.sub.2./sub.O and N.sub.2./sub. in situ at intervals over 74 H.
|
|
|
Symptomes of nitrogen excess in soil
Hynšt, Jaroslav ; Šimek, Miloslav
Nitrogen cycling is one of the most important processes on the Earth. Most of N transformations run in soil. Nitrogen usually enters the soil as occasional input in concentrated forms which means that it is often in excess or in deficit. However, deficit and excess of N have different value in different soils and ecosystems. For example, amount of N which causes significant impact on ecosystem of spruce forest is insufficient for the maize field. This suggests, that the amount of N in soil must be evaluated in context of the whole ecosystem. In N-limited ecosystems, most of N is stored in plant biomass and litter characterized by slow transformations. Productivity of ecosystem is low, but N is utilized with high efficiency. On the other hand, in conditions of high availability of N, losses take place. These differences are reflected in content of different fractions of soluble N in soil and different rates of their transformations.
|
|
|
Soil micromycetes - the potential source of N.sub.2./sub.O in soils
Jirout, Jiří ; Šimek, Miloslav ; Elhottová, Dana
The aim of this paper is to summarize knowledge on potential production of N.sub.2./sub.O by fungi. The processes involved in the global nitrogen cycle are suggested to have an important role in the global environmental changes. Nitrification and denitrification processes cotribute to the production of N.sub.2./sub.O, which belongs to the group of highly active greenhouse gases. Denitrification - the successive reduction of nitrate to N.sub.2./sub. - was supposed to occur only in prokaryotes, but recently the evidence for dissimilation of nitrates and formation of nitrogen oxides and N.sub.2./sub. was reported also in fungi. N.sub.2./sub.O of fungal origin is formed from nitrate or nitrite by reduction under anaerobic or microaerobic conditions. Since fungi showed the capability to use denitrification and oxygen respiration simultaneously under various pO.sub.2./sub. conditions, the N.sub.2./sub.O production by fungi is expected in a wide range of soils with different aeration status.
|
|
|
Soil microorganisms as controllers of methane emission from soils
Elhottová, Dana ; Němcová, Anna ; Chroňáková, Alica ; Šimek, Miloslav
The pilot study on functional microbial groups responsible for methanogenic and methanotrophic processes in soil of specific model ecosystem – the cattle overwintering pasture was given. The enrichment by methanogenic archaea was shown in soils strongly impacted due to cattle pasture. The increased methanogenic abundance was accompanied by increased abundance of methylotrophic bacteria. Nevertheless, the ratio of methylotrophic to methanogenic microorganisms was significantly higher in the control soils without cattle impact in comparison to the cattle-impacted soils.
|
|
|
Nitrogen and carbon transformation processes in soil in permanent grasslands - research in cattle overwintering area
Šimek, Miloslav ; Hynšt, Jaroslav ; Čuhel, Jiří ; Elhottová, Dana ; Chroňáková, Alica ; Němcová, Anna ; Jirout, Jiří ; Krištůfek, Václav
Agricultural soils represent a significant source of greenhouse gases (carbon dioxide, nitrous oxide and methane). Pasture soils and especially overwintering areas receive large amounts of nutrients as animal excrements. Together with other effects, this creates good conditions for high rates of nitrogen and carbon transformations, and also for substantial losses in the form of gaseous metabolites. This paper informs on research of a specific model ecosystem – the cattle overwintering area. Research is focused either on the structure of soil microbial community and on its activities including the formation of gases in, and their emission from the soil to atmosphere.
|
|
|
Quantification of key genes in nitrification and denitrification
Chroňáková, Alica ; Čuhel, Jiří ; Radl, V. ; Elhottová, Dana ; Šimek, Miloslav
The objective of the study was to explore the long-term effect of cattle grazing activities on abundance of nitrifying and denitrifying communities on overwintering area. The abundances of studied populations were determined using qPCR method and copy numbers of .i.amoA, nirS,./i. and .i.nirK./i. genes were quantified in spring and fall. High input of cattle urine and excrements with other animal activities had a significant impact on abundance of nitrifying and denitrifying bacteria, being higher in cattle impacted soils in comparison to control. Our data also showed that abundance of both bacterial communities reflected seasonal changes.
|
|
| |
|
|
Emissions of greenhouse gases (N2O and CO2) from pasture soil as a result of activity of soil microbial community - preliminary results
Šimek, Miloslav ; Hynšt, Jaroslav ; Brůček, Petr ; Čuhel, Jiří
Cattle overwintering area was shown an important point source of N2O and CO2. The emissions of N2O were mostly directly related to the rate of animal impact as the greatest fluxes of N2O and the highest total cumulative N2O emissions as well were found at the most impacted site. The fluxes of N2O were however very variable in time and most of N2O was emitted during several short events in spring or in winter. Laboratory experiments suggested that total amount of nitrogen escaping from soil from impacted sites is much greater than indicated by field measurements of N2O fluxes and molecular nitrogen (N2) was shown as the main nitrogen gas. It is hypothesized that soil pH is a crucial soil factor controlling the mole fraction of N2O: under slightly alkaline conditions in severely impacted soils, denitrification is completed and most of nitrogen escapes from the soil as N2; under more acidic conditions, however, the activity of nitrous oxide reductase is partly reduced.
|
guest ::
RSS feed.