| 1. |
- Börjesson, Gunnar, et al.
(författare)
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Microbial oxidation of CH4 at high partial pressures in an organic landfill cover soil under different moisture regimes
- 1998
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Ingår i: FEMS Microbiology Ecology. - 0168-6496. ; 26:3, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- The uptake and utilization of CH4 at high concentrations (5-18% vol.) and different soil moistures were followed for samples from a landfill cover soil with a high organic matter content. Measurements of the utilization of CH4 and O2, and production of CO2 indicated that the activity of methanotrophic organisms accounted for most of the O2 respiration. At water saturation, CH4 oxidation rates decreased with time, probably because NH4/+ accumulated. Denitrification rates, estimated based on both N2 and N2O production, were positively related to soil moisture and only slightly influenced by the extent of CH4 oxidation. Total phospholipid fatty acid concentrations increased, and concentrations of phospholipid fatty acids, typical for obligate methanotrophic bacteria (e.g. 16:1ω8 and 18:1ω8), increased in the CH4-amended samples, indicating growth of both type I and type II methanotrophs.
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| 2. |
- Olsson, Pål Axel, et al.
(författare)
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Interactions between ectomycorrhizal fungi and the bacterial community in soils amended with various primary minerals
- 1998
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Ingår i: FEMS Microbiology Ecology. - 0168-6496. ; 27:2, s. 195-205
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Tidskriftsartikel (refereegranskat)abstract
- The influence of ectomycorrhizal fungi on the soil bacterial community was studied by growing pine seedlings in artificial soils consisting of a peat/sand mixture amended with microcline, biotite or apatite. In the microcline-amended and unamended soils both Suillus variegatus and Paxillus involutus reduced bacterial activity as measured by thymidine incorporation. S. variegatus grew best in the biotite soil, where it increased both bacterial activity and biomass as measured by microscopic counts and specific bacterial fatty acids. Further, the positive influence of S. variegatus on the bacteria in the biotite soil modified the bacterial community, as reflected in the bacteria-specific phospholipid fatty acid composition. The increases in bacterial biomass and activity and changes in the bacterial community induced by S. variegatus may be due to the production of organic substances by this fungus, as indicated by an 10-fold increase in soil-solution citric acid. Two isolates of S. variegatus and an unidentified ectomycorrhizal fungus all tended to stimulate bacterial activity in the apatite-amended soil in compartments isolated from roots by a mesh. We conclude that the same ectomycorrhizal fungus may stimulate bacterial growth under certain conditions and inhibit bacterial growth under other conditions. Copyright (C) 1998 Federation of European Microbiological Societies.
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| 3. |
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| 4. |
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| 5. |
- Langenheder, Silke, et al.
(författare)
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Salinity as a structuring factor for the composition and performance of bacterioplankton degrading riverine DOC
- 2003
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Ingår i: FEMS Microbiology Ecology. - 0168-6496 .- 1574-6941. ; 45:2, s. 189-202
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Tidskriftsartikel (refereegranskat)abstract
- The impact of salinity on the composition and functional performance (biomass production, growth efficiency and growth rates) of bacterial communities was investigated using batch cultures growing on dissolved organic carbon from a river draining into the Northern Baltic Sea. The cultures were adjusted to riverine or estuarine salinity levels and inoculated with bacteria from these two environments. Bacterial growth efficiencies differed in response to salinity and the origin of the inoculum. When salinity was adjusted to correspond to the salinity at the site where the inoculum was retrieved, growth efficiency was relatively high (11.5 +/- 2.6%). However, when bacteria were confronted with a shift in salinity, growth efficiency was lower (7.5 +/- 2.0%) and more of the utilized carbon was respired. In contrast, growth rates were higher when bacteria were exposed to a change in salinity. The composition of the bacterial communities developing in the batch cultures differed, as shown by 16S rDNA DGGE, depending on the origin of the inoculum and salinity. Reverse and direct DNA-DNA hybridization revealed salinity optima in the growth of specific bacterial strains as well as broader phylogenetic groups. Strains belonging to the alpha- and beta-Proteobacteria, Actinobacteria and gamma-Proteobacteria other than the genus Pseudomonas showed higher relative abundance under freshwater conditions, whereas strains of the genus Pseudomonas and the Cytophaga-Flavobacterium-Bacteroides group were favored by estuarine conditions. Generally, our results demonstrate functional changes associated with changes in community composition. We suggest that even moderate changes in salinity affect bacterial community composition, which subsequently leads to altered growth characteristics. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
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| 6. |
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| 7. |
- Wikner, Johan, 1961-, et al.
(författare)
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NUCLEIC-ACIDS FROM THE HOST BACTERIUM AS A MAJOR SOURCE OF NUCLEOTIDES FOR 3 MARINE BACTERIOPHAGES
- 1993
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Ingår i: FEMS Microbiology Ecology. - Amsterdam : Elsevier. - 0168-6496 .- 1574-6941. ; 12:4, s. 237-248
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Tidskriftsartikel (refereegranskat)abstract
- The incorporation of P-32-phosphorus into marine bacteriophage nucleic acid was studied in culture experiments to investigate the source of nucleotides used by the phage. We consistently found that the P-32-specific activity in the phage genome increased during the 11 h incubation and was low relative to the specific activity in the medium, averaging 21% (+/- SD 5.9) for the three phage isolates. This was in accordance with a mathematical model where most of the nucleotides for phage DNA synthesis were derived from the host cell nucleic acid rather than de novo synthesis. We propose that this metabolic strategy may be common among marine phages, as an adaptation to a nutrient poor environment. Consequently, the contribution of free DNA to the dissolved fraction through phage lysis of bacteria, may be less that previously thought. Also during radiolabelling of bacteriophages in natural water samples, isotope dilution may be dependent on the specific growth rate of the bacterial host.
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| 9. |
- Adomas, Aleksandra, et al.
(författare)
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Identification and analysis of differentially expressed cDNAs during nonself-competitive interaction between Phlebiopsis gigantea and Heterobasidion parviporum
- 2006
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Ingår i: FEMS Microbiology Ecology. - : Blackwell Publishing. - 0168-6496 .- 1574-6941. ; 57:1, s. 26-39
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Tidskriftsartikel (refereegranskat)abstract
- The molecular factors regulating interspecific interaction between the saprotrophic biocontrol fungus Phlebiopsis gigantea and the conifer pathogen Heterobasidion parviporum were investigated. We constructed cDNA libraries and used expressed sequence tag analysis for the identification and characterization of genes expressed during the self and nonself-hyphal interaction. cDNA clones from either the pathogen or biocontrol agent were arrayed on nylon membrane filters and differentially screened with cDNA probes made from mycelia forming the barrage zone during nonself-interactions, mycelia growing outside the barrage zones or monocultures. BlastX analysis of the differentially expressed clones led to the identification of genes with diverse functions, including those with potential as virulence factors, such as hydrophobins. Because of the high sequence conservation (r2 = 0.81) between P. gigantea and H. parviporum, a selected number of genes from either fungus were used to monitor the expression profile under varying interaction conditions by virtual northern blot. The results are discussed with respect to the potential role of the induced genes during the nonself-competitive interaction for space and nutrients between P. gigantea and H. parviporum.
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