| 1. |
- Granhall, Ulf, et al.
(författare)
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Bacterial community diversity in paper mills processing recycled paper
- 2010
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Ingår i: Journal of Industrial Microbiology & Biotechnology. - : Oxford University Press (OUP). - 1367-5435 .- 1476-5535. ; 37:10, s. 1061-1069
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Tidskriftsartikel (refereegranskat)abstract
- Paper mills processing recycled paper suffer from biofouling causing roblems both in the mill and final product. The total bacterial ommunity composition and identification of specific taxa in the process ater and biofilms at the stock preparation and paper machine areas in a ill with recycled paper pulp was described by using a DNA-based pproach. Process water in a similar mill was also analyzed to nvestigate if general trends can be found between mills and over time. acterial community profiles, analyzed by terminal-restriction fragment ength polymorphism (T-RFLP), in process water showed that the dominant eaks in the profiles were similar between the two mills, although the verall composition was unique for each mill. When comparing process ater and biofilm at different locations within one of the mills, we bserved a separation according to location and sample type, with the iofilm from the paper machine being most different. 16S rRNA gene clone ibraries were generated and 404 clones were screened by RFLP analysis. rouping of RFLP patterns confirmed that the biofilm from the paper achine was most different. A total of 99 clones representing all RFLP atterns were analyzed, resulting in sequences recovered from nine acterial phyla, including two candidate phyla. Bacteroidetes epresented 45% and Actinobacteria 23% of all the clones. Sequences with imilarity to organisms implicated in biofouling, like Chryseobacterium pp. and Brevundimonas spp., were recovered from all samples even though he mill had no process problems during sampling, suggesting that they re part of the natural paper mill community. Moreover, many sequences howed little homology to as yet uncultivated bacteria implying that aper mills are interesting for isolation of new organisms, as well as or bioprospecting.
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| 2. |
- Hallin, Sara, et al.
(författare)
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Soil Functional Operating Range Linked to Microbial Biodiversity and Community Composition Using Denitrifiers as Model Guild
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Soil microorganisms are key players in biogeochemical cycles. Yet, there is no consistent view on the significance of microbial biodiversity for soil ecosystem functioning. According to the insurance hypothesis, declines in ecosystem functioning due to reduced biodiversity are more likely to occur under fluctuating, extreme or rapidly changing environmental conditions. Here, we compare the functional operating range, a new concept defined as the complete range of environmental conditions under which soil microbial communities are able to maintain their functions, between four naturally assembled soil communities from a long-term fertilization experiment. A functional trait approach was adopted with denitrifiers involved in nitrogen cycling as our model soil community. Using short-term temperature and salt gradients, we show that the functional operating range was broader and process rates were higher when the soil community was phylogenetically more diverse. However, key bacterial genotypes played an important role for maintaining denitrification as an ecosystem functioning under certain conditions.
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| 3. |
- Jones, Christopher, et al.
(författare)
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Phenotypic and genotypic heterogeneity among closely related soil-borne N-2- and N2O-producing Bacillus isolates harboring the nosZ gene
- 2011
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 76, s. 541-552
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the genetic and phenotypic diversity of Gram-positive denitrifying bacteria. We compared the production of gaseous denitrification products for 14 closely related Bacillus soil isolates at pH 6 and 7 during 48-h batch incubations using a robotic gas-sampling apparatus. Primers targeting the nosZ gene encoding the nitrous oxide reductase were designed to confirm the presence of this gene in the isolates. The variation in the production of gaseous nitrogen products was compared with the genetic variation based on 16S rRNA gene sequences, genomic fingerprinting and nosZ sequences. The nosZ gene was detected in all isolates and all produced N-2 as the dominant end product at pH 7. Production of gaseous nitrogen products was more variable at pH 6, with different levels of NO and N2O production among the isolates, although minimal variation was observed among the 16S rRNA and nosZ gene sequences. One isolate was more divergent from the others based on genomic fingerprinting, and had two different nosZ gene copies, which coincided with the highest production of N-2 at pH 7 and the lack of intermediates at pH 6. Overall, our analysis suggests that genetic variation plays a role in the variation in N2O and N-2 production, but the variation in activity caused by acidification can be substantially greater than genotypic variation among closely related Bacillus.
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| 4. |
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| 5. |
- Welsh, Allana, et al.
(författare)
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Microbial functional diversity enhances predictive models linking environmental parameters to ecosystem properties
- 2015
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 96, s. 1985-1993
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Tidskriftsartikel (refereegranskat)abstract
- Microorganisms drive biogeochemical processes, but linking these processes to real changes in microbial communities under field conditions is not trivial. Here, we present a model-based approach to estimate independent contributions of microbial community shifts to ecosystem properties. The approach was tested empirically, using denitrification potential as our model process, in a spatial survey of arable land encompassing a range of edaphic conditions and two agricultural production systems. Soil nitrate was the most important single predictor of denitrification potential (the change in Akaike's information criterion, corrected for sample size, AIC(c) = 20.29); however, the inclusion of biotic variables (particularly the evenness and size of denitrifier communities [AIC(c) = 12.02], and the abundance of one denitrifier genotype [AIC(c) = 18.04]) had a substantial effect on model precision, comparable to the inclusion of abiotic variables (biotic R-2 = 0.28, abiotic R-2 = 0.50, biotic + abiotic R-2 = 0.76). This approach provides a valuable tool for explicitly linking microbial communities to ecosystem functioning. By making this link, we have demonstrated that including aspects of microbial community structure and diversity in biogeochemical models can improve predictions of nutrient cycling in ecosystems and enhance our understanding of ecosystem functionality.
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| 6. |
- Wessén, Ella, et al.
(författare)
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Spatial distribution of ammonia-oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning
- 2011
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Ingår i: Isme Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 5:7, s. 1213-1225
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Tidskriftsartikel (refereegranskat)abstract
- Characterization of spatial patterns of functional microbial communities could facilitate the understanding of the relationships between the ecology of microbial communities, the biogeochemical processes they perform and the corresponding ecosystem functions. Because of the important role the ammonia-oxidizing bacteria (AOB) and archaea (AOA) have in nitrogen cycling and nitrate leaching, we explored the spatial distribution of their activity, abundance and community composition across a 44-ha large farm divided into an organic and an integrated farming system. The spatial patterns were mapped by geostatistical modeling and correlations to soil properties and ecosystem functioning in terms of nitrate leaching were determined. All measured community components for both AOB and AOA exhibited spatial patterns at the hectare scale. The patchy patterns of community structures did not reflect the farming systems, but the AOB community was weakly related to differences in soil pH and moisture, whereas the AOA community to differences in soil pH and clay content. Soil properties related differently to the size of the communities, with soil organic carbon and total nitrogen correlating positively to AOB abundance, while clay content and pH showed a negative correlation to AOA abundance. Contrasting spatial patterns were observed for the abundance distributions of the two groups indicating that the AOB and AOA may occupy different niches in agro-ecosystems. In addition, the two communities correlated differently to community and ecosystem functions. Our results suggest that the AOA, not the AOB, were contributing to nitrate leaching at the site by providing substrate for the nitrite oxidizers. The ISME Journal (2011) 5, 1213-1225; doi:10.1038/ismej.2010.206; published online 13 January 2011 Subject Category: microbial ecology and functional diversity of natural habitats
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