Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    The Fate of 15N-Nitrate in Healthy and Declining Phragmites australis Stands (1997)
    Springer
    Microbial ecology 34 (1997), S. 254-262 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dissimilatory nitrate-reducing processes, denitrification, and dissimilatory nitrate-reduction to ammonium were studied in freshwater lake sediments within healthy and degrading Phragmites australis (reed) stands. The samples from the healthy vegetation site contained roots and rhizomes. Cores were supplied with 1.9–5.2 μg 15N-NO3 − g−1 dry sediment in the laboratory and subsequently incubated for 8 h at 20°C, in the dark. The 15N compounds were determined before (natural percentage of 15N) and after 1 and 8 h of incubation. The uptake of 15N by the roots and rhizomes in the healthy vegetation was 61%. Nitrogen losses, interpreted as denitrification, accounted for 25 and 84% of the added 15N-NO3 − in sediment from the healthy and degrading vegetation sites, respectively. The percentages of nitrate reduced to ammonium were 4 and 9% in sediment from the healthy vegetation and degrading vegetation sites, respectively. The percentage of 15N–total N in the sediment of the healthy vegetation site was 10%, whereas for the degrading vegetation site this percentage was 7%. The percentage of nitrate reduced to ammonium could be potentially underestimated by the percentage of 15N measured in the sediment. In this case, in healthy and degenerating P. australis stands, the percentage of produced ammonium accounted for 14–16%. The nitrate reduction rates were calculated based on an incubation period of one hour. The denitrification rate in sediment from the degrading vegetation site was higher than from the healthy vegetation site. The rate of dissimilatory nitrate reduction to ammonium was almost tenfold higher in sediment from the degrading vegetation site compared to sediment from the healthy vegetation site. The significantly lower percentages of dissimilatory nitrate reduction to ammonium and denitrification in the healthy stand compared to the degrading stand was probably due to the presence of roots and rhizomes. In the sediments of healthy and degrading P. australis stands, denitrification was the main nitrate-reducing process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002489900055
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Nitrification in the rhizosphere of a flooding-resistant and a flooding-non-resistant Rumex species under drained and waterlogged conditions (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 86 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The effects of the flooding-resistant plant species Rumex palustris and the non-flooding-resistant plant species Rumex acetosa on nitrification were compared. The plants were grown under drained and waterlogged conditions on a mixture of calcareous riversand and sieved grassland soil with a high potential nitrifying activity. In the shoots of R. acetosa, but not in those of R. palustris, the ratio between the amounts of accumulated carboxylates and organic nitrogen, ((CA-A)/Norg.), appeared to be a useful indicator of ammonium or nitrate consumption by tghe plant. In both plant species, the inorganic nitrogen source had no observed effect on the (C-A)/Norg. ratio in the roots.The growth of R. acetosa, but not that of R. palustris was inhibited by waterlogging of the soil. Both the activity and the growth of the ammonium-oxidizing bacteria were repressed under drained and waterlogged conditions in soils with R. palustris, a condition that was attributed to a competitive ammonium uptake by its relatively fast growing roots. In the presence of R. acetosa, the activity and growth of the ammonium-oxidizing bacteria were inhibited under waterlogged, but not under drained, conditions. he growth and activity of nitrite-oxidizing bacteria in the absence of actively ammonium-oxidizing, nitrite-producing bacteria was likely due to organotrophic growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04793.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effect of nitrite concentration and pH on most probable number enumerations of non-growing Nitrobacter spp. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 85 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Enumerations of nitrite-oxidizing bacteria in soil samples by a Most Probable Number technique, often showed relatively high cell numbers at a low nitrite concentration compared with the numbers of ammonium-oxidizing bacteria. It was hypothesized that the high numbers enumerated at low nitrite concentration would represent non-growing or organotrophically growing cells of nitrite-oxidizing species. In this paper, the sensitivity of non-growing Nitrobacter species to high nitrite concentrations as well as to low pH was examined. Different Nitrobacter species were pre-cultured at 0.5 mM nitrite. Non-growing cells differing in age were enumerated at different nitrite concentrations and pH values. The incubation period lasted for 5 months at 20°C. However, during the incubation periods of the older non-growing cells, it appeared that a period of 5 months might have been too short for reaching constant numbers. Early stationary cells of all species that were studied appeared not to be affected by high nitrite concentrations or low pH. Eight- and 18-month-old non-growing cells of Nitrobacter hamburgensis were also insensitive to 5 mM nitrite. The numbers of 8- and 18-month-old resting cells of N. vulgaris were only repressed by a combination of 5 mM nitrite and a low pH. Eight-month-old non-growing cells of N. winogradskyi were sensitive to 5 mM irrespective of pH, but 18-month-old cells only to 5 mM nitrate at low pH. The numbers of 8- and 18-month-old resting cells of N. winogradskyi serotype agilis were repressed by low pH rather than high nitrite concentration. Hence, it was concluded that the large differences in numbers of nitrite-oxidizing bacteria obtained with low and high nitrite concentrations in the incubation medium, was not likely to be due to the presence of non-growing Nitrobacter species in soil samples, but rather to the existence of organotrophically growing Nitrobacter cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04753.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Enumeration of nitrite-oxidizing bacteria in grassland soils using a Most Probable Number technique: Effect of nitrite concentration and sampling procedure (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 74 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Numbers of nitrite-oxidizing bacteria were determined in grassland soils using a Most Probable Number technique. Two concentrations of nitrite were used in the incubation medium, i.e. 0.05 and 5.0 mM. The results of the enumerations were highly dependent on the nitrite concentration as well as on the grassland soil sampled. In the one soil the highest numbers were counted with 5.0 mM, whereas in other soils highest numbers were obtained in media with 0.05 mM nitrite. The spatial distribution of nitrite-oxidizing bacteria was determined i two field plots. Variation between individual samples was low in one plot and high in the other. The implications of the observed differences for the sampling procedure in each sampling plot are discussed. In the waterlogged, oxygen-limited soils, numbers of nitrite-oxidizing bacteria were as high as in the drained soils. The chemolitho-autotrophic nature of these nitrifiers has been confirmed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04074.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Most Probable Numbers of chemolitho-autotrophic nitrite-oxidizing bacteria in well drained grassland soils: Stimulation by high nitrite concentrations (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 74 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The results of Most Probable Number (MPN) enumerations of chemolitho-autotrophic nitrite oxidizers are very much dependent on the nitrite concentration applied in the incubation medium. In order to explain this dependency, the influence of pH, nitrite and resultant nitrous acid concentration of the incubation medium on the MPN-enumeration was investigated. It appeared that none of these factors were exclusively responsible for the result of the enumeration. In samples from a well drained grassland soil, highest number have been obtained with a combination of a low pH and a low nitrite concentration in the counting medium. The relation between the MPN-counting results and the nitrous acid concentration showed an optimum with the same soil samples. It was hypothesized that the relatively high numbers of nitrite-oxidizing cells determined in soil samples at a high nitrite concentration and pH 7.3 was due to the presence of dormant cells. However, this hypothesis could not be confirmed with enumerations of aged cell suspensions of different Nitrobacter species. In contrast to the field observations, these resting cells were always enumerated more efficiently at a low nitrite concentration. The importance of the use of more than one incubation medium for the enumeration of nitrite-oxidizing bacteria is emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04075.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Seasonal changes in percentages of attached bacteria enumerated in a tidal and a stagnant coastal basin: relation to bacterioplankton productivity (1986)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 38 (1986), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract As part of an extensive ecosystem study, the fate of the bacterioplankton community was followed in the tidal Oosterschelde basin and in the stagnant but saline Lake Grevelingen, The Netherlands. At regular intervals, bacterioplankton biomass, percentages of bacteria attached to particles, bacterioplankton productivity and oxygen consumption rates, together with a number of environmental parameters, were determined. With respect to biomass, productivity and oxygen consumption rates, no significant differences were observed between the two coastal basins. However, the mean percentages of attached bacteria were high in the tidal Oosterschelde basin compared to the stagnant Lake Grevelingen. This could be explained by the observed difference in amounts of colonizable particles. On an annual basis, however, the percentages of attached bacteria were not significantly correlated with the amounts of suspended particles at the sampling stations. A significant, but negative correlation was found between the percentages of attached bacteria and the bacterioplankton productivities at the sampling stations. A probable mechanism for such a negative correlation is discussed.By size fractionation experiments, bacterioplankton contribution to overall oxygen consumption rates was determined. These contributions amounted to 58% and 94% in spring and winter, respectively. From specific bacterioplankton dissimilation and assimilation rates, mean bacterioplankton carbon conversion coefficients of 26% and 6% were calculated in spring and winter, respectively. These percentages are discussed in the light of probable seasonal differences in the supply of substrates for the bacterioplankton community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1986.tb01956.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Isolation of an aspartate-fermenting, free-living campylobacter species (1977)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 1 (1977), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1977.tb00590.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The effect of the incubation period on the result of MPN enumerations of nitrite-oxidizing bacteria: theoretical considerations (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 85 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A computer model based on Monod- and Haldane-kinetics was used to estimate the minimum incubation period required for MPN enumerations of nitrite-oxidizing bacteria. The minimum incubation period was defined as the time needed for one cell, present in the tubes inoculated with the highest dilutions, to grow into a population that oxidized all the nitrite present at the start of the incubation. Kinetic parameters used in the model were derived from literature data and applied in different combinations. The results show that the minimum incubation period may increase with decreasing initial nitrite concentrations in the incubation medium. They also show that the opposite trend, i.e. increasing minimum incubation periods with increasing nitrite concentration periods with increasing nitrite concentration, can be explained by introducing a term for substrate inhibition in the model. A MPN enumeration result obtained with samples from a waterlogged peat bog soil could only partly be explained by the model if only one set of parameters was used. This indicates that the community of nitrite-oxidizing bacteria in this soil is composed of at least two types of nitrite-oxidizing bacteria, with different kinetic parameters of nitrite oxidation and growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04760.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Temporal and spatial variation in the nitrite-oxidizing bacterial community of a grassland soil (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 10 (1992), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The temporal and spatial distribution of the nitrite-oxidizing community of a non-fertilized, semi-natural grassland soil was studied to obtain more insight into the possible variation in nitrate production in this soil throughout the year. Data describing the size, potential nitrite-oxidizing activity and serotype composition of the nitrite-oxidizing community are reported. In addition, several abiotic soil parameters potentially related to the activity of this community were measured. Whereas numbers and potential activities largely varied with time and place, the specific affinity for nitrite oxidation, defined as the ratio VmaxKm, was relatively constant. The serotypes Nitrobacter agilis, N. winogradskyi and N. hamburgensis were all present in the top 5-cm soil in every 500-g sample examined, showing that these species co-exist in this soil.By principal component analyses performed with the parameters describing aspects of the community, i.e. most probable numbers, serotype numbers and potential nitrite-oxidizing activities, it was demonstrated that these parameters were all affected in a different way by yet unknown factors. This was confirmed by stepwise regression analyses. If significant, the different biotic parameters correlated with different abiotic factors. Hence, none of the biotic parameters emerged from this study as an indicator that should be used preferentially for the description of the nitrite-oxidizing community in a grassland soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1992.tb00004.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Repression of nitrification in soils under a climax grassland vegetation (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 14 (1994), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Two hypotheses on repression of nitrification in climax vegetations (i.e. nitrogen immobilization and allelopathy) were investigated. In this study the potential nitrification activities and numbers of ammonium-oxidizing bacteria were established in a nature reserve with a series of natural grasslands with vegetational different stages of succession of plants species. The pastures had not been fertilized for 3, 7, 20 and 46 years, respectively, and the gradual decrease in availability of nutrients had led to pastures dominated by different grass species. In each field soil parameters, potential nitrification activities (PNA) and numbers of ammonium-oxidizing bacteria were determined in the root zone of Holcus lanatus as well as in that of a grass species characteristic of the stage of succession. In the rhizosphere of H. lanatus decreasing PNA and numbers of ammonium-oxidizing bacteria were observed as the period of non fertilization increased. Within each field no significant differences in PNA were observed between the root zones of H. lanatus and those of the dominant grass species. From these results it is concluded that, in these fields, decreasing nitrification was related only to decreasing ammonium availability and not to species composition. No indications were obtained that allelochemicals were involved in the flow nitrification potentials of late stages of succession. The optimum pH of the ammonium-oxidizing community, measured as PNA, decreased as the period of non fertilization increased. It is suggested that impoverishment of the grassland soil with respect to nitrogen availability selects against ammonium-oxidizing bacteria with a relatively high pH optimum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1994.tb00089.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...