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  • 1. Algesten, Grete
    et al.
    Sobek, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Bergström, Ann-Kristin
    Jonsson, Anders
    Tranvik, Lars J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Jansson, Mats
    Contribution of sediment respiration to summer CO2 emission from low productive boreal and subarctic lakes2005In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 50, no 4, p. 529-535Article in journal (Refereed)
    Abstract [en]

    We measured sediment production of carbon dioxide (CO2) and methane (CH4) and the net flux of CO2 across the surfaces of 15 boreal and subarctic lakes of different humic contents. Sediment respiration measurements were made in situ under ambient light conditions. The flux of CO2 between sediment and water varied between an uptake of 53 and an efflux of 182 mg C m−2 day−1 from the sediments. The mean respiration rate for sediments in contact with the upper mixed layer (SedR) was positively correlated to dissolved organic carbon (DOC) concentration in the water (r 2 = 0.61). The net flux of CO2 across the lake surface [net ecosystem exchange (NEE)] was also closely correlated to DOC concentration in the upper mixed layer (r 2 = 0.73). The respiration in the water column was generally 10-fold higher per unit lake area compared to sediment respiration. Lakes with DOC concentrations <5.6 mg L−1 had net consumption of CO2 in the sediments, which we ascribe to benthic primary production. Only lakes with very low DOC concentrations were net autotrophic (<2.6 mg L−1) due to the dominance of dissolved allochthonous organic carbon in the water as an energy source for aquatic organisms. In addition to previous findings of allochthonous organic matter as an important driver of heterotrophic metabolism in the water column of lakes, this study suggests that sediment metabolism is also highly dependent on allochthonous carbon sources.

  • 2.
    Drakare, Stina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Limnology.
    Competition between picoplanktonic cyanobacteria and heterotrophic bacteria along crossed gradients of glucose and phosphate2002In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 44, no 4, p. 327-335Article in journal (Refereed)
    Abstract [en]

    A laboratory experiment was performed to test whether differences in nutrient and energy demands between picophytoplankton and heterotrophic bacteria can explain the apparent inverse biomass relationship between these organisms in lakes along gradients of organic carbon and nutrients. Growth rates and final yield of cells were analyzed in crossed gradients of glucose and phosphate. Concentrations of phosphate (10, 25, and 60 microg P L(-1)) and glucose (0, 0.3, and 3 mg C L(-1)) were used in all possible combinations giving 9 different treatments. Heterotrophic bacteria had higher maximum growth rates in all treatments and became larger than picophytoplankton in many treatments. The variance in abundance of heterotrophic bacteria between treatments could almost completely be explained by the combined effects of glucose and P. In treatments where carbon limitation slowed down the growth of heterotrophic bacteria, picophytoplankton became abundant and these organisms showed a positive response to P in combination with a negative response to glucose. The negative effect of glucose on picophytoplankton is suggested to be indirect and caused by competition with bacteria that are favored by organic C. The results suggest that competition for phosphate between phytoplankton and bacteria is not size-dependent, that heterotrophic bacteria are superior competitors for P, and that organic C produced by picophytoplankton was of minor importance for heterotrophic bacteria.

  • 3. Hjort, Karin
    et al.
    Lembke, Antje
    Speksnijder, Arjen
    Smalla, Kornelia
    Jansson, Janet K
    Community structure of actively growing bacterial populations in plant pathogen suppressive soil.2007In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 53, no 3, p. 399-413Article in journal (Refereed)
    Abstract [en]

    The bacterial community in soil was screened by using various molecular approaches for bacterial populations that were activated upon addition of different supplements. Plasmodiophora brassicae spores, chitin, sodium acetate, and cabbage plants were added to activate specific bacterial populations as an aid in screening for novel antagonists to plant pathogens. DNA from growing bacteria was specifically extracted from the soil by bromodeoxyuridine immunocapture. The captured DNA was fingerprinted by terminal restriction fragment length polymorphism (T-RFLP). The composition of the dominant bacterial community was also analyzed directly by T-RFLP and by denaturing gradient gel electrophoresis (DGGE). After chitin addition to the soil, some bacterial populations increased dramatically and became dominant both in the total and in the actively growing community. Some of the emerging bands on DGGE gels from chitin-amended soil were sequenced and found to be similar to known chitin-degrading genera such as Oerskovia, Kitasatospora, and Streptomyces species. Some of these sequences could be matched to specific terminal restriction fragments on the T-RFLP output. After addition of Plasmodiophora spores, an increase in specific Pseudomonads could be observed with Pseudomonas-specific primers for DGGE. These results demonstrate the utility of microbiomics, or a combination of molecular approaches, for investigating the composition of complex microbial communities in soil.

  • 4. Jansson, Mats
    et al.
    Bergström, Ann-Kristin
    Lymer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Vrede, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Karlsson, Jan
    Bacterioplankton growth and nutrient use efficiencies under variable organic carbon and inorganic phosphorus ratios2006In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 52, no 2, p. 358-364Article in journal (Refereed)
    Abstract [en]

    We carried out enclosure experiments in an unproductive lake in northern Sweden and studied the effects of enrichment with different dissolved organic carbon (glucose)/inorganic phosphorous (DOC/Pi) ratios on bacterioplankton production (BP), growth efficiency (BGE), nutrient use efficiency (BNUE), growth rate, and specific respiration. We found considerable variation in BP, BGE, and BNUE along the tested DOC/Pi gradient. BGE varied between 0.87 and 0.24, with the highest values at low DOC/Pi ratios. BNUE varied between 40 and 9 g C g P-1, with high values at high DOC/Pi ratios. More DOC was thus allocated to growth when bacteria tended to be C-limited, and to respiration when bacteria were P-limited. Specific respiration was positively correlated with bacterial growth rate throughout the gradient. It is therefore possible that respiration was used to support growth in P-limited bacteria. The results indicated that BP can be limited by Pi when BNUE is at its maximum, by organic C when BGE is at its maximum, and by dual organic C and Pi limitation when BNUE and BGE have suboptimal values.

  • 5.
    Nilsson, Louise K. J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Swedish Univ Agr Sci SLU, Dept Ecol, POB 7044, S-75007 Uppsala, Sweden.
    Rodrigues de Oliveira, Marta
    Univ Estado Amazonas, Programa Posgrad Biotecnol & Recursos Nat Amazoni, BR-69065001 Manaus, Amazonas, Brazil.
    Marinotti, Osvaldo
    Univ Calif Irvine, Dept Mol Biol & Biochem, 3205 Mc Gaugh Hall, Irvine, CA 92697 USA.
    Matos Rocha, Elerson
    Univ Fed Amazonas, Programa Posgrad Biotecnol, Manaus, Amazonas, Brazil; Inst Nacl de Pesquisas da Amazonia, Lab Malaria & Dengue, BR-69011970 Manaus, Amazonas, Brazil.
    Håkansson, Sebastian
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Uppsala BioCtr, POB 7025, S-75007 Uppsala, Sweden.
    Tadei, Wanderli P.
    Univ Estado Amazonas, Programa Posgrad Biotecnol & Recursos Nat Amazoni, BR-69065001 Manaus, Amazonas, Brazil.
    Queiroz Lima de Souza, Antonia
    Univ Estado Amazonas, Programa Posgrad Biotecnol & Recursos Nat Amazoni, BR-69065001 Manaus, Amazonas, Brazil; Univ Fed Amazonas FCA UFAM, Fac Ciencias Agr, BR-69080900 Manaus, Amazonas, Brazil.
    Terenius, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Swedish Univ Agr Sci SLU, Dept Ecol, POB 7044, S-75007 Uppsala, Sweden.
    Characterization of Bacterial Communities in Breeding Waters of Anopheles darlingi in Manaus in the Amazon Basin Malaria-Endemic Area2019In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 78, no 4, p. 781-791Article in journal (Refereed)
    Abstract [en]

    The microbiota in mosquito breeding waters can affect ovipositing mosquitoes, have effects on larval development, and can modify adult mosquito-gut bacterial composition. This, in turn, can affect transmission of human pathogens such as malaria parasites. Here, we explore the microbiota of four breeding sites for Anopheles darlingi, the most important malaria vector in Latin America. The sites are located in Manaus in the Amazon basin in Brazil, an area of active malaria transmission. Using 16S rRNA gene sequencing by MiSeq, we found that all sites were dominated by Proteobacteria and Firmicutes and that 94% of the total number of reads belonged to 36 operational taxonomic units (OTUs) identified in all sites. Of these, the most common OTUs belonged to Escherichia/Shigella, Staphylococcus, and Pseudomonas. Of the remaining 6% of the reads, the OTUs found to differentiate between the four sites belonged to the orders Burkholderiales, Actinomycetales, and Clostridiales. We conclude that An. darlingi can develop in breeding waters with different surface-water bacteria, but that the common microbiota found in all breeding sites might indicate or contribute to a suitable habitat for this important malaria vector.

  • 6.
    Romeralo, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organism Biology, Systematic Biology.
    Moya-Larano, Jordi
    Lado, Carlos
    Social Amoebae: Environmental Factors Influencing Their Distribution and Diversity Across South-Western Europe2011In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 61, no 1, p. 154-165Article in journal (Refereed)
    Abstract [en]

    The social amoebae (dictyostelids) are the only truly multicellular lineage within the superkingdom Amoebozoa, the sister group to Ophistokonts (Metazoa+Fungi). Despite the exceptional phylogenetic and evolutionary value of this taxon, the environmental factors that determine their distribution and diversity are largely unknown. We have applied statistical modeling to a set of data obtained from an extensive and detailed survey in the south-western of Europe (The Iberian Peninsula including Spain and Portugal) in order to estimate some of the main environmental factors influencing the distribution and diversity of dictyostelid in temperate climates. It is the first time that this methodology is applied to the study of this unique group of soil microorganisms. Our results show that a combination of climatic (temperature, water availability), physical (pH) and vegetation (species richness) factors favor dictyostelid species richness. In the Iberian Peninsula, dictyostelid diversity is highest in colder and wet environments, indicating that this group has likely diversified in relatively cold places with high levels of water availability.

  • 7.
    Schneider, Salome
    et al.
    Swedish Univ Agr Sci SLU, Dept Microbiol, Uppsala, Sweden.;Swiss Fed Res Inst WSL, Biodivers & Conservat Biol, Birmensdorf, Switzerland..
    Tajrin, Tania
    Swedish Univ Agr Sci SLU, Dept Microbiol, Uppsala, Sweden..
    Lundström, Jan O.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Nedre Dalalvens Utvecklings AB, Swedish Biol Mosquito Control Project, Gysinge, Sweden.
    Hendriksen, Niels B.
    Aarhus Univ, Dept Environm Sci, Roskilde, Denmark..
    Melin, Petter
    Swedish Chem Agcy, Sundbyberg, Sweden..
    Sundh, Ingvar
    Swedish Univ Agr Sci SLU, Dept Microbiol, Uppsala, Sweden.;Swedish Univ Agr Sci SLU, Dept Mol Sci, Uppsala, Sweden..
    Do Multi-year Applications of Bacillus thuringiensis subsp israelensis for Control of Mosquito Larvae Affect the Abundance of B-cereus Group Populations in Riparian Wetland Soils?2017In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 74, no 4, p. 901-909Article in journal (Refereed)
    Abstract [en]

    Bacillus thuringiensis subsp. israelensis (Bti) is a soil-borne bacterium affiliated to the Bacillus cereus group (Bcg) and has been used in biocontrol products against nematoceran larvae for several decades. However, knowledge is limited on whether long-term Bti application can affect the structure of indigenous communities of Bcg and the overall abundance of Bti. Using species- and group-specific quantitative PCR assays, we measured the Bcg- and Bti-abundances in riparian wetlands in the River Dalalven floodplains of central Sweden. On five occasions during one vegetative season, soil samples were collected in alder swamps and wet meadows which had been treated with Bti for mosquito larvae control during the preceding 11 years, as well as in untreated control sites and well-drained forests in the same area. The average abundance of Bcg in alder swamps was around three times higher than in wet meadows. Across all sites and habitats, the Bti treatments had no effect on the Bcg-abundance, whereas the Bti-abundance was significantly higher in the treated than in the control sites. However, for individual sampling sites, abundances of Bti and Bcg were not correlated with the number of Bti applications, indicating that added Bti possibly influenced the total population of Bti in the short term but had only a limited effect in the longer term. The findings of this study increase the understanding of the ecology of Bti applications for mosquito control, which can facilitate environmental risk assessment in connection with approval of microbiological control agents.

  • 8. Sylvander, Peter
    et al.
    Häubner, Norbert
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Snoeijs, Pauline
    The Thiamine Content of Phytoplankton Cells Is Affected by Abiotic Stress and Growth Rate2013In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 65, no 3, p. 566-577Article in journal (Refereed)
    Abstract [en]

    Thiamine (vitamin B-1) is produced by many plants, algae and bacteria, but by higher trophic levels, it must be acquired through the diet. We experimentally investigated how the thiamine content of six phytoplankton species belonging to five different phyla is affected by abiotic stress caused by changes in temperature, salinity and photon flux density. Correlations between growth rate and thiamine content per cell were negative for the five eukaryotic species, but not for the cyanobacterium Nodularia spumigena. We demonstrate a high variability in thiamine content among phytoplankton species, with the highest content in N. spumigena. Salinity was the factor with the strongest effect, followed by temperature and photon flux density, although the responses varied between the investigated phytoplankton species. Our results suggest that regime shifts in phytoplankton community composition through large-scale environmental changes has the potential to alter the thiamine availability for higher trophic levels. A decreased access to this essential vitamin may have serious consequences for aquatic food webs.

  • 9. Székely, Anna J.
    et al.
    Sipos, Rita
    Berta, Birgitta
    Vajna, Balázs
    Hajdú, Csaba
    Márialigeti, Károly
    DGGE and T-RFLP analysis of bacterial succession during mushroom compost production and sequence-aided T-RFLP profile of mature compost2009In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 57, no 3, p. 522-533Article in journal (Refereed)
    Abstract [en]

    The amount of button mushroom (Agaricus bisporus) harvested from compost is largely affected by the microbial processes taking place during composting and the microbes inhabiting the mature compost. In this study, the microbial changes during the stages of this specific composting process were monitored, and the dominant bacteria of the mature compost were identified to reveal the microbiological background of the favorable properties of the heat-treated phase II mushroom compost. 16S ribosomal deoxyribonucleic acid (rDNA)-based denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) molecular fingerprinting methods were used to track the succession of microbial communities in summer and winter composting cycles. DNA from individual DGGE bands were reamplified and subjected to sequence analysis. Principal component analysis of fingerprints of the composting processes showed intensive changes in bacterial community during the 22-day procedure. Peak temperature samples grouped together and were dominated by Thermus thermophilus. Mature compost patterns were almost identical by both methods (DGGE, T-RFLP). To get an in-depth analysis of the mature compost bacterial community, the sequence data from cultivation of the bacteria and cloning of environmental 16S rDNA were uniquely coupled with the output of the environmental T-RFLP fingerprints (sequence-aided T-RFLP). This method revealed the dominance of a supposedly cellulose-degrading consortium composed of phylotypes related to Pseudoxanthomonas, Thermobifida, and Thermomonospora. © 2008 Springer Science+Business Media, LLC.

  • 10. Thelaus, J.
    et al.
    Andersson, A.
    Broman, T.
    Backman, S.
    Granberg, M.
    Karlsson, L.
    Kuoppa, K.
    Larsson, E.
    Lundmark, E.
    Lundström, Jan O.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Mathisen, P.
    Naslund, J.
    Schäfer, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Wahab, T.
    Forsman, M.
    Francisella tularensis Subspecies holarctica Occurs in Swedish Mosquitoes, Persists Through the Developmental Stages of Laboratory-Infected Mosquitoes and Is Transmissible During Blood Feeding2014In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 67, no 1, p. 96-107Article in journal (Refereed)
    Abstract [en]

    In Sweden, mosquitoes are considered the major vectors of the bacterium Francisella tularensis subsp. holarctica, which causes tularaemia. The aim of this study was to investigate whether mosquitoes acquire the bacterium as aquatic larvae and transmit the disease as adults. Mosquitoes sampled in a Swedish area where tularaemia is endemic (A-rebro) were positive for the presence of F. tularensis deoxyribonucleic acid throughout the summer. Presence of the clinically relevant F. tularensis subsp. holarctica was confirmed in 11 out of the 14 mosquito species sampled. Experiments performed using laboratory-reared Aedes aegypti confirmed that F. tularensis subsp. holarctica was transstadially maintained from orally infected larvae to adult mosquitoes and that 25 % of the adults exposed as larvae were positive for the presence of F. tularensis-specific sequences for at least 2 weeks. In addition, we found that F. tularensis subsp. holarctica was transmitted to 58 % of the adult mosquitoes feeding on diseased mice. In a small-scale in vivo transmission experiment with F. tularensis subsp. holarctica-positive adult mosquitoes and susceptible mice, none of the animals developed tularaemia. However, we confirmed that there was transmission of the bacterium to blood vials by mosquitoes that had been exposed to the bacterium in the larval stage. Taken together, these results provide evidence that mosquitoes play a role in disease transmission in part of Sweden where tularaemia recurs.

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