Browsing by Subject "microbes"

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  • Fagerholm, Freja (Helsingin yliopisto, 2021)
    In the process of decomposition soil carbon is transformed into CO2 by microbial respiration, which makes decomposition a key process for understanding carbon cycling an releases of CO2. Since the northern permafrost regions contain half of all belowground carbon and the tundra regions are expected to be markedly affected by climate warming, it is of particular interest to understand how warming will affect decomposition in the tundra. Decomposition is however influenced by many factors, from climatic factors such as temperature and precipitation to the belowground organisms inhabiting the soils and the aboveground system dictating the litter that falls to the ground and is decomposed. Further, grazing has been shown to oppose some of the effects of warming on tundra. In this thesis I analyzed data collected from two long-term field experiments, one in Kilpisjärvi (NW Finland) and the other close to Kangerlussuaq Fjord (SW Greenland), both using fencing for manipulation of grazing regime and open-top chambers for artificial warming. My aim was to not only investigate how warming and grazing affect decomposition, but also to understand whether the magnitude of changes in decomposition can be explained by changes in plant community traits and soil characteristics. I found that in contrast to my hypothesis, warming decreased decomposition in Kangerlussuaq, where the soil was drier and contained less carbon than in Kilpisjärvi. I found no effects of grazing on decomposition, plant community traits nor soil characteristics in neither of the study locations. Neither did I find any consistent associations between changes in decomposition and changes in plant community traits, indicating that the effect of litter quality on decomposition is minor in these areas likely rather limited by climate. I found an association for increased decomposition when plant community C:N ratio and C:P ratio increased as a response to warming, but only in Kilpisjärvi, and since increased plant community C:N and C:P ratios are linked to resistant litter this positive effect is unlikely driven by enhanced litter quality. However, I did find a positive relationship between increased root biomass and increased decomposition as a response to warming that was consistent across areas and grazing regimes, indicating that warming can boost decomposition in different tundra habitats by promoting root growth.
  • Riskumäki, Matilda; Tessas, Ioannis; Ottman, Noora; Suomalainen, Alina; Werner, Paulina; Karisola, Piia; Lauerma, Antti; Ruokolainen, Lasse; Karkman, Antti; Wisgrill, Lukas; Sinkko, Hanna; Lehtimäki, Jenni; Alenius, Harri; Fyhrquist, Nanna (European Academy of Allergy and Clinical Immunology, 2021)
    Allergy 76: 4, 1280-1284
  • Egamberdieva, Dilfuza; Wirth, Stephan; Li, Li; Abd-Allah, Elsayed Fathi; Lindström, Kristina (2017)
    Liquorice (Glycyrrhiza uralensis Fisch.) is one of the most widely used plants in food production, and it can also be used as an herbal medicine or for reclamation of salt-affected soils. Under salt stress, inhibition of plant growth, nutrient acquisition and symbiotic interactions between the medicinal legume liquorice and rhizobia have been observed. We recently evaluated the interactions between rhizobia and root-colonizing Pseudomonas in liquorice grown in potting soil and observed increased plant biomass, nodule numbers and nitrogen content after combined inoculation compared to plants inoculated with Mesorhizobium alone. Several beneficial effects of microbes on plants have been reported; studies examining the interactions between symbiotic bacteria and root-colonizing Pseudomonas strains under natural saline soil conditions are important, especially in areas where a hindrance of nutrients and niches in the rhizosphere are high. Here, we summarize our recent observations regarding the combined application of rhizobia and Pseudomonas on the growth and nutrient uptake of liquorice as well as the salt stress tolerance mechanisms of liquorice by a mutualistic interaction with microbes. Our observations indicate that microbes living in the rhizosphere of liquorice can form a mutualistic association and coordinate their involvement in plant adaptations to stress tolerance. These results support the development of combined inoculants for improving plant growth and the symbiotic performance of legumes under hostile conditions.
  • Campbell, Karley; Matero, Ilkka; Bellas, Christopher; Turpin-Jelfs, Thomas; Anhaus, Philipp; Graeve, Martin; Fripiat, Francois; Tranter, Martyn; Landy, Jack Christopher; Sanchez-Baracaldo, Patricia; Leu, Eva; Katlein, Christian; Mundy, C. J; Rysgaard, Søren; Tedesco, Letizia; Haas, Christian; Nicolaus, Marcel (Royal Swedish Academy of Sciences, 2022)
    Sea ice continues to decline across many regions of the Arctic, with remaining ice becoming increasingly younger and more dynamic. These changes alter the habitats of microbial life that live within the sea ice, which support healthy functioning of the marine ecosystem and provision of resources for human-consumption, in addition to influencing biogeochemical cycles (e.g. air–sea CO2 exchange). With the susceptibility of sea ice ecosystems to climate change, there is a pressing need to fill knowledge gaps surrounding sea ice habitats and their microbial communities. Of fundamental importance to this goal is the development of new methodologies that permit effective study of them. Based on outcomes from the DiatomARCTIC project, this paper integrates existing knowledge with case studies to provide insight on how to best document sea ice microbial communities, which contributes to the sustainable use and protection of Arctic marine and coastal ecosystems in a time of environmental change.
  • Huttunen, Kati; Wlodarczyk, Anna J.; Tirkkonen, Jenni; Mikkonen, Santtu; Täubel, Martin; Krop, Esmeralda; Jacobs, Jose; Pekkanen, Juha; Heederik, Dick; Zock, Jan-Paul; Hyvärinen, Anne; Hirvonen, Maija-Riitta; Adams, Rachel; Jones, Tim; Zimmermann, Ralf; BeruBe, Kelly (2019)
    Exposure to moisture-damaged indoor environments is associated with adverse respiratory health effects, but responsible factors remain unidentified. In order to explore possible mechanisms behind these effects, the oxidative capacity and hemolytic activity of settled dust samples (n = 25) collected from moisture-damaged and non-damaged schools in Spain, the Netherlands, and Finland were evaluated and matched against the microbial content of the sample. Oxidative capacity was determined with plasmid scission assay and hemolytic activity by assessing the damage to isolated human red blood cells. The microbial content of the samples was measured with quantitative PCR assays for selected microbial groups and by analyzing the cell wall markers ergosterol, muramic acid, endotoxins, and glucans. The moisture observations in the schools were associated with some of the microbial components in the dust, and microbial determinants grouped together increased the oxidative capacity. Oxidative capacity was also affected by particle concentration and country of origin. Two out of 14 studied dust samples from moisture-damaged schools demonstrated some hemolytic activity. The results indicate that the microbial component connected with moisture damage is associated with increased oxidative stress and that hemolysis should be studied further as one possible mechanism contributing to the adverse health effects of moisture-damaged buildings.