Expedited evolution of soil bacteria exposed to organic contaminants

We tested two hypotheses for which support can be found in the literature. (1) the degradation of organic contaminants is faster in humus soil than in mineral soil and (2) the degradation of organic contaminants is faster in previously contaminated soil than in similar but previously non-contaminated soil

DOC and CO2-C Releases from Pristine and Drained Peat Soils in Response to Water Table Fluctuations: A Mesocosm Experiment

Peer reviewe

Nitrogen Release in Pristine and Drained Peat Profiles in Response to Water Table Fluctuations : A Mesocosm Experiment

Peer reviewe

Process rates of nitrogen cycle in uppermost topsoil after harvesting in no-tilled and ploughed agricultural clay soil

No-till is considered an agricultural practice beneficial for the environment as soil erosion is decreased compared to ploughed soils. For on overall evaluation of the benefits and disadvantages of this crop production method, understanding the soil nutrient cycle is also of importance. The study was designed to obtain information about gross soil nitrogen (N) process rates in boreal no-tilled and mouldboard ploughed spring barley (Hordeum vulgare L.) fields after autumn harvesting. In situ soil gross N transformation process rates were quantified for the 5 cm topsoil in 9 days' incubation experiment using N-15 pool dilution and tracing techniques and a numerical N-15 tracing model. Gross N mineralization into ammonium (NH4+) and NH4+ immobilization were the most important N transformation processes in the soils. The gross mineralization rate was 14% and NH4+ immobilization rate 64% higher in no-till than in ploughing. Regardless of the faster mineralization, the gross rate of NH4+ oxidation into nitrate (NO3-) in no-till was one order of magnitude lower compared the ploughing. The results indicate that the no-tilled soils have the potential to decrease the risk for NO3- leaching due to slower NH4+ oxidation.Peer reviewe

Analyses of Sporocarps, Morphotyped Ectomycorrhizae, Environmental ITS and LSU Sequences Identify Common Genera that Occur at a Periglacial Site

Abstract: Periglacial substrates exposed by retreating glaciers represent extreme and sensitive environments defined by a variety of abiotic stressors that challenge organismal establishment and survival. The simple communities often residing at these sites enable their analyses in depth. We utilized existing data and mined published sporocarp, morphotyped ectomycorrhizae (ECM), as well as environmental sequence data of internal transcribed spacer (ITS) and large subunit (LSU) regions of the ribosomal RNA gene to identify taxa that occur at a glacier forefront in the North Cascades Mountains in Washington State in the USA. The discrete data types consistently identified several common and widely distributed genera, perhaps best exemplified by Inocybe and Laccaria. Although we expected low diversity and richness, our environmental sequence data included 37 ITS and 26 LSU operational taxonomic units (OTUs) that likely form ECM. While environmental surveys of metabarcode markers detected large numbers of targeted ECM taxa, both the fruiting body and the morphotype datasets included genera that were undetected in either of the metabarcode datasets. These included hypogeous (Hymenogaster) and epigeous (Lactarius) taxa, some of which may produce large sporocarps but may possess small and/or spatially patchy genets. We highlight the importance of combining various data types to provide a comprehensive view of a fungal community, even in an environment assumed to host communities of low species richness and diversity.Peer reviewe

The abundance of health-associated bacteria is altered in PAH polluted soils-Implications for health in urban areas?

Long-term exposure to polyaromatic hydrocarbons (PAHs) has been connected to chronic human health disorders. It is also well-known that i) PAH contamination alters soil bacterial communities, ii) human microbiome is associated with environmental microbiome, and iii) alteration in the abundance of members in several bacterial phyla is associated with adverse or beneficial human health effects. We hypothesized that soil pollution by PAHs altered soil bacterial communities that had known associations with human health. The rationale behind our study was to increase understanding and potentially facilitate reconsidering factors that lead to health disorders in areas characterized by PAH contamination. Large containers filled with either spruce forest soil, pine forest soil, peat, or glacial sand were left to incubate or contaminated with creosote. Biological degradation of PAHs was monitored using GC-MS, and the bacterial community composition was analyzed using 454 pyrosequencing. Proteobacteria had higher and Actinobacteria and Bacteroidetes had lower relative abundance in creosote contaminated soils than in non-contaminated soils. Earlier studies have demonstrated that an increase in the abundance of Proteobacteria and decreased abundance of the phyla Actinobacteria and Bacteroidetes are particularly associated with adverse health outcomes and immunological disorders. Therefore, we propose that pollution-induced shifts in natural soil bacterial community, like in PAH-polluted areas, can contribute to the prevalence of chronic diseases. We encourage studies that simultaneously address the classic "adverse toxin effect" paradigm and our novel "altered environmental microbiome" hypothesis.Peer reviewe

Cadmium release from afforested peatlands and accumulation in an aquatic ecosystem after experimental wood ash treatment

v2012o

Twenty years of research on fungus-microbe-plant interactions on Lyman Glacier forefront – lessons learned and questions yet unanswered

Retreating glaciers and the periglacial areas they vacate for organismal colonization produce a harsh environment of extreme radiation, nutrient limitations, and temperature oscillations. They provide a model system for studying mechanisms that drive establishment and early assembly of communities. Here, we synthesize more than twenty years of research at the Lyman Glacier forefront in the North Cascades Mountains, comparing the results and conclusions for plant and microbial communities. Compared to plant communities, the trajectories and processes of microbial community development are difficult to deduce. However, the combination of high throughput sequencing, more revealing experimental designs, and analyses of phylogenetic community provide insights into mechanisms that shape early microbial communities. While the inoculum is likely randomly drawn from regional pools and accumulates over time, our data provide no support for increases in richness over time since deglaciation as is commonly observed for plant communities. Re‐analyses of existing datasets suggest that microbial, particularly fungal, communities are insensitive to time since substrate exposure from underneath the retreating glacier but responsive to plant establishment both in biomass and community composition. Further research on functional aspects, organismal activity, or ecosystem services in early successional environments will provide deeper appreciation for the dynamics of these communities