Publications by authors named "Hannu Fritze"

40 Publications

Site fertility and soil water-table level affect fungal biomass production and community composition in boreal peatland forests.

Environ Microbiol 2021 10 9;23(10):5733-5749. Epub 2021 Jan 9.

Natural Resources Institute Finland (LUKE), Natural Resources, Latokartanonkaari 9, Helsinki, FI-00790, Finland.

A substantial amount of below-ground carbon (C) is suggested to be associated with fungi, which may significantly affect the soil C balance in forested ecosystems. Ergosterol from in-growth mesh bags and litterbags was used to estimate fungal biomass production and community composition in drained peatland forests with differing fertility. Extramatrical mycelia (EMM) biomass production was generally higher in the nutrient-poor site, increased with deeper water table level and decreased along the length of the recovery time. EMM biomass production was of the same magnitude as in mineral-soil forests. Saprotrophic fungal biomass production was higher in the nutrient-rich site. Both ectomycorrhizal (ECM) and saprotrophic fungal community composition changed according to site fertility and water table level. ECM fungal community composition with different exploration types may explain the differences in fungal biomass production between peatland forests. Melanin-rich Hyaloscypha may indicate decreased turnover of biomass in nutrient-rich young peatland forest. Genera Lactarius and Laccaria may be important in nutrient rich and Piloderma in the nutrient-poor conditions, respectively. Furthermore, Paxillus involutus and Cortinarius sp. may be important generalists in all sites and responsible for EMM biomass production during the first summer months. Saprotrophs showed a functionally more diverse fungal community in the nutrient-rich site.
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http://dx.doi.org/10.1111/1462-2920.15368DOI Listing
October 2021

Pulp and paper mill sludges decrease soil erodibility.

J Environ Qual 2021 Jan 8;50(1):172-184. Epub 2020 Dec 8.

Natural Resources Institute Finland, Tietotie 4, Jokioinen, FI-31600, Finland.

Declining carbon (C) content in agricultural soils threatens soil fertility and makes soil prone to erosion, which could be rectified with organic soil amendments. In a 4-yr field trial, we made a single application of three different organic sludges from the pulp and paper industry and studied their effects on cereal yield, soil C content, and fungal and bacterial composition. In laboratory rainfall simulations, we also studied the effects of the soil amendments on susceptibility to erosion and nutrient mobilization of a clay-textured soil by measuring the quality of percolation water passing through 40-cm intact soil monoliths during 2-d rainfall simulations over four consecutive years after application. A nutrient-poor fiber sludge reduced wheat yield in the first growing season, but there were no other significant effects on cereal yield or grain quality. An input of ∼8 Mg ha C with the soil amendments had only minor effects on soil C content after 4 yr, likely because of fast microbe-mediated turnover. The amendments clearly changed the fungal and bacterial community composition. All amendments significantly reduced suspended solids (SS) and total phosphorus (TP) concentrations in percolation water. The effect declined with time, but the reduction in SS and TP was still >25% 4 yr after application. We attributed the lower tendency for particle detachment in rain simulations to direct interactions of soil minerals with the added particulate organic matter and microbe-derived compounds that stabilize soil aggregates. In soils with low organic matter content, pulp and paper industry by-products can be a viable measure for erosion mitigation.
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http://dx.doi.org/10.1002/jeq2.20170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898543PMC
January 2021

Are there environmental or agricultural benefits in using forest residue biochar in boreal agricultural clay soil?

Sci Total Environ 2020 Aug 28;731:138955. Epub 2020 Apr 28.

Natural Resources Institute Finland, Tietotie 4, FI-31600 Jokioinen, Finland.

Short-term agronomic and environmental benefits are fundamental factors in encouraging farmers to use biochar on a broad scale. The short-term impacts of forest residue biochar (BC) on the productivity and carbon (C) storage of arable boreal clay soil were studied in a field experiment. In addition, rain simulations and aggregate stability tests were carried out to investigate the potential of BC to reduce nutrient export to surface waters. A BC addition of 30 t ha increased soil test phosphorus and decreased bulk density in the surface soil but did not significantly change pH or water retention properties, and most importantly, did not increase the yield. There were no changes in the bacterial or fungal communities, or biomasses. Soil basal respiration was higher in BC-amended plots in the spring, but no differences in respiration rates were detected in the fall two years after the application. Rain simulation experiments did not support the use of BC in reducing erosion or the export of nutrients from the field. Of the C added, on average 80% was discovered in the 0-45 cm soil layer one year after the application. Amendment of boreal clay soil with a high rate of BC characterized by a moderately alkaline pH, low surface functionalities, and a recalcitrant nature, did not induce such positive impacts that would unambiguously motivate farmers to invest in BC. BC use seems unviable from the farmer's perspective but could play a role in climate change mitigation, as it will likely serve as long-term C storage.
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http://dx.doi.org/10.1016/j.scitotenv.2020.138955DOI Listing
August 2020

Editorial: special issue on the ecology of soil microorganisms.

FEMS Microbiol Ecol 2019 12;95(12)

The Czech Academy of Sciences, Prague.

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http://dx.doi.org/10.1093/femsec/fiz154DOI Listing
December 2019

Plant roots increase both decomposition and stable organic matter formation in boreal forest soil.

Nat Commun 2019 09 4;10(1):3982. Epub 2019 Sep 4.

Department of Agricultural Sciences, University of Helsinki, PO Box 66, Helsinki, Finland.

Boreal forests are ecosystems with low nitrogen (N) availability that store globally significant amounts of carbon (C), mainly in plant biomass and soil organic matter (SOM). Although crucial for future climate change predictions, the mechanisms controlling boreal C and N pools are not well understood. Here, using a three-year field experiment, we compare SOM decomposition and stabilization in the presence of roots, with exclusion of roots but presence of fungal hyphae and with exclusion of both roots and fungal hyphae. Roots accelerate SOM decomposition compared to the root exclusion treatments, but also promote a different soil N economy with higher concentrations of organic soil N compared to inorganic soil N accompanied with the build-up of stable SOM-N. In contrast, root exclusion leads to an inorganic soil N economy (i.e., high level of inorganic N) with reduced stable SOM-N build-up. Based on our findings, we provide a framework on how plant roots affect SOM decomposition and stabilization.
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http://dx.doi.org/10.1038/s41467-019-11993-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6726645PMC
September 2019

Warming impacts on boreal fen CO exchange under wet and dry conditions.

Glob Chang Biol 2019 06 2;25(6):1995-2008. Epub 2019 Apr 2.

School of Forest Sciences, University of Eastern Finland, Joensuu, Finland.

Northern peatlands form a major soil carbon (C) stock. With climate change, peatland C mineralization is expected to increase, which in turn would accelerate climate change. A particularity of peatlands is the importance of soil aeration, which regulates peatland functioning and likely modulates the responses to warming climate. Our aim is to assess the impacts of warming on a southern boreal and a sub-arctic sedge fen carbon dioxide (CO ) exchange under two plausible water table regimes: wet and moderately dry. We focused this study on minerotrophic treeless sedge fens, as they are common peatland types at boreal and (sub)arctic areas, which are expected to face the highest rates of climate warming. In addition, fens are expected to respond to environmental changes faster than the nutrient poor bogs. Our study confirmed that CO exchange is more strongly affected by drying than warming. Experimental water level draw-down (WLD) significantly increased gross photosynthesis and ecosystem respiration. Warming alone had insignificant impacts on the CO exchange components, but when combined with WLD it further increased ecosystem respiration. In the southern fen, CO uptake decreased due to WLD, which was amplified by warming, while at northern fen it remained stable. As a conclusion, our results suggest that a very small difference in the WLD may be decisive, whether the C sink of a fen decreases, or whether the system is able to adapt within its regime and maintain its functions. Moreover, the water table has a role in determining how much the increased temperature impacts the CO exchange.
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http://dx.doi.org/10.1111/gcb.14617DOI Listing
June 2019

Carbon flux from decomposing wood and its dependency on temperature, wood N fixation rate, moisture and fungal composition in a Norway spruce forest.

Glob Chang Biol 2019 05 20;25(5):1852-1867. Epub 2019 Mar 20.

Natural Resources Institute Finland (Luke), Helsinki, Finland.

Globally 40-70 Pg of carbon (C) are stored in coarse woody debris on the forest floor. Climate change may reduce the function of this stock as a C sink in the future due to increasing temperature. However, current knowledge on the drivers of wood decomposition is inadequate for detailed predictions. To define the factors that control wood respiration rate of Norway spruce and to produce a model that adequately describes the decomposition process of this species as a function of time, we used an unprecedentedly diverse analytical approach, which included measurements of respiration, fungal community sequencing, N fixation rate, nifH copy number, C-dating as well as N%, δ C and C% values of wood. Our results suggest that climate change will accelerate C flux from deadwood in boreal conditions, due to the observed strong temperature dependency of deadwood respiration. At the research site, the annual C flux from deadwood would increase by 27% from the current 117 g C/kg wood with the projected climate warming (RCP4.5). The second most important control on respiration rate was the stage of wood decomposition; at early stages of decomposition low nitrogen content and low wood moisture limited fungal activity while reduced wood resource quality decreased the respiration rate at the final stages of decomposition. Wood decomposition process was best described by a Sigmoidal model, where after 116 years of wood decomposition mass loss of 95% was reached. Our results on deadwood decomposition are important for C budget calculations in ecosystem and climate change models. We observed for the first time that the temperature dependency of N fixation, which has a major role at providing N for wood-inhabiting fungi, was not constant but varied between wood density classes due to source supply and wood quality. This has significant consequences on projecting N fixation rates for deadwood in changing climate.
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http://dx.doi.org/10.1111/gcb.14594DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6849867PMC
May 2019

Impact of hexamine addition to a nitrite-based additive on fermentation quality, Clostridia and Saccharomyces cerevisiae in a white lupin-wheat silage.

J Sci Food Agric 2019 Mar 19;99(4):1492-1500. Epub 2018 Oct 19.

Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland.

Background: Nitrite and hexamine are used as silage additives because of their adverse effects on Clostridia and Clostridia spores. The effect of sodium nitrite and sodium nitrite/hexamine mixtures on silage quality was investigated. A white lupin-wheat mixture was treated with sodium nitrite (NaHe0) (900 g t forage), or mixtures of sodium nitrite (900 g t ) and hexamine. The application rate of hexamine was 300 g t (NaHe300) or 600 g t (NaHe600). Additional treatments were the untreated control (Con), and formic acid (FA) applied at a rate of 4 L t (1000 g kg ).

Results: Additives improved silage quality noticeably only by reducing silage ammonia content compared with the control. The addition of hexamine to a sodium nitrite solution did not improve silage quality compared with the solution containing sodium nitrite alone. The increasing addition of hexamine resulted in linearly rising pH values (P < 0.001) and decreasing amounts of lactic acid (P < 0.01). Sodium nitrite based additives were more effective than formic acid in preventing butyric acid formation. Additives did not restrict the growth of Saccharomyces cerevisiae compared to the control.

Conclusion: The addition of hexamine did not improve silage quality compared with a solution of sodium nitrite. © 2018 Society of Chemical Industry.
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http://dx.doi.org/10.1002/jsfa.9322DOI Listing
March 2019

Ericoid plant species and Pinus sylvestris shape fungal communities in their roots and surrounding soil.

New Phytol 2018 04 1;218(2):738-751. Epub 2018 Mar 1.

Department of Microbiology, University of Helsinki, PO Box 56, FIN-00014, Helsinki, Finland.

Root-colonizing fungi can form mycorrhizal or endophytic associations with plant roots, the type of association depending on the host. We investigated the differences and similarities of the fungal communities of three boreal ericoid plants and one coniferous tree, and identified the community structure of fungi utilizing photosynthates from the plants studied. The fungal communities of roots and soils of Vaccinium myrtillus, Vaccinium vitis-idaea, Calluna vulgaris and Pinus sylvestris were studied in an 18-month-long experiment where the plants were grown individually in natural substrate. Photosynthates utilizing fungi were detected with DNA stable-isotope probing using CO ( C-DNA-SIP). The results indicated that the plants studied provide different ecological niches preferred by different fungal species. Those fungi which dominated the community in washed roots had also the highest C-uptake. In addition, a common root endophyte without confirmed mycorrhizal status also obtained C from all the plants, indicating close plant-association of this fungal species. We detect several fungal species inhabiting the roots of both ericoid mycorrhizal and ectomycorrhizal plants. Our results highlight that the ecological role of co-occurrence of fungi with different life styles (e.g. mycorrhizal or endophytic) in plant root systems should be further investigated.
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http://dx.doi.org/10.1111/nph.15040DOI Listing
April 2018

Impact of Peat Mining and Restoration on Methane Turnover Potential and Methane-Cycling Microorganisms in a Northern Bog.

Appl Environ Microbiol 2018 02 17;84(3). Epub 2018 Jan 17.

Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, the Netherlands

Ombrotrophic peatlands are a recognized global carbon reservoir. Without restoration and peat regrowth, harvested peatlands are dramatically altered, impairing their carbon sink function, with consequences for methane turnover. Previous studies determined the impact of commercial mining on the physicochemical properties of peat and the effects on methane turnover. However, the response of the underlying microbial communities catalyzing methane production and oxidation have so far received little attention. We hypothesize that with the return of spp. postharvest, methane turnover potential and the corresponding microbial communities will converge in a natural and restored peatland. To address our hypothesis, we determined the potential methane production and oxidation rates in natural (as a reference), actively mined, abandoned, and restored peatlands over two consecutive years. In all sites, the methanogenic and methanotrophic population sizes were enumerated using quantitative PCR (qPCR) assays targeting the and genes, respectively. Shifts in the community composition were determined using Illumina MiSeq sequencing of the gene and a -based terminal restriction fragment length polymorphism (t-RFLP) analysis, complemented by cloning and sequence analysis of the gene. Peat mining adversely affected methane turnover potential, but the rates recovered in the restored site. The recovery in potential activity was reflected in the methanogenic and methanotrophic abundances. However, the microbial community composition was altered, being more pronounced for the methanotrophs. Overall, we observed a lag between the recovery of the methanogenic/methanotrophic activity and the return of the corresponding microbial communities, suggesting that a longer duration (>15 years) is needed to reverse mining-induced effects on the methane-cycling microbial communities. Ombrotrophic peatlands are a crucial carbon sink, but this environment is also a source of methane, an important greenhouse gas. Methane emission in peatlands is regulated by methane production and oxidation catalyzed by methanogens and methanotrophs, respectively. Methane-cycling microbial communities have been documented in natural peatlands. However, less is known of their response to peat mining and of the recovery of the community after restoration. Mining exerts an adverse impact on potential methane production and oxidation rates and on methanogenic and methanotrophic population abundances. Peat mining also induced a shift in the methane-cycling microbial community composition. Nevertheless, with the return of spp. in the restored site after 15 years, methanogenic and methanotrophic activity and population abundance recovered well. The recovery, however, was not fully reflected in the community composition, suggesting that >15 years are needed to reverse mining-induced effects.
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http://dx.doi.org/10.1128/AEM.02218-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5772240PMC
February 2018

Responses of phenology and biomass production of boreal fens to climate warming under different water-table level regimes.

Glob Chang Biol 2018 03 13;24(3):944-956. Epub 2017 Nov 13.

School of Forest Sciences, University of Eastern Finland, Joensuu, Finland.

Climate change affects peatlands directly through increased air temperatures and indirectly through changes in water-table level (WL). The interactions of these two still remain poorly known. We determined experimentally the separate and interactive effects of temperature and WL regime on factors of relevance for the inputs to the carbon cycle: plant community composition, phenology, biomass production, and shoot:root allocation in two wet boreal sedge-dominated fens, "southern" at 62°N and "northern" at 68°Ν. Warming (1.5°C higher average daily air temperature) was induced with open-top chambers and WL drawdown (WLD; 3-7 cm on average) by shallow ditches. Total biomass production varied from 250 to 520 g/m , with belowground production comprising 25%-63%. Warming was associated with minor effects on phenology and negligible effects on community composition, biomass production, and allocation. WLD clearly affected the contribution of different plant functional types (PFTs) in the community and the biomass they produced: shrubs benefited while forbs and mosses suffered. These responses did not depend on the warming treatment. Following WLD, aboveground biomass production decreased mainly due to reduced growth of mosses in the southern fen. Aboveground vascular plant biomass production remained unchanged but the contribution of different PFTs changed. The observed changes were also reflected in plant phenology, with different PFTs showing different responses. Belowground production increased following WLD in the northern fen only, but an increase in the contributions of shrubs and forbs was observed in both sites, while sedge contribution decreased. Moderate warming alone seems not able to drive significant changes in plant productivity or community composition in these wet ecosystems. However, if warming is accompanied by even modest WL drawdown, changes should be expected in the relative contribution of PFTs, which could lead to profound changes in the function of fens. Consequently, hydrological scenarios are of utmost importance when estimating their future function.
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http://dx.doi.org/10.1111/gcb.13934DOI Listing
March 2018

Distinct Anaerobic Bacterial Consumers of Cellobiose-Derived Carbon in Boreal Fens with Different CO2/CH4 Production Ratios.

Appl Environ Microbiol 2017 02 1;83(4). Epub 2017 Feb 1.

Natural Resources Institute Finland, Helsinki, Finland.

Northern peatlands in general have high methane (CH) emissions, but individual peatlands show considerable variation as CH sources. Particularly in nutrient-poor peatlands, CH production can be low and exceeded by carbon dioxide (CO) production from unresolved anaerobic processes. To clarify the role anaerobic bacterial degraders play in this variation, we compared consumers of cellobiose-derived carbon in two fens differing in nutrient status and the ratio of CO to CH produced. After [C]cellobiose amendment, the mesotrophic fen produced equal amounts of CH and CO The oligotrophic fen had lower CH production but produced 3 to 59 times more CO than CH RNA stable-isotope probing revealed that in the mesotrophic fen with higher CH production, cellobiose-derived carbon was mainly assimilated by various recognized fermenters of Firmicutes and by Proteobacteria The oligotrophic peat with excess CO production revealed a wider variety of cellobiose-C consumers, including Firmicutes and Proteobacteria, but also more unconventional degraders, such as Telmatobacter-related Acidobacteria and subphylum 3 of Verrucomicrobia Prominent and potentially fermentative Planctomycetes and Chloroflexi did not appear to process cellobiose-C. Our results show that anaerobic degradation resulting in different levels of CH production can involve distinct sets of bacterial degraders. By distinguishing cellobiose degraders from the total community, this study contributes to defining anaerobic bacteria that process cellulose-derived carbon in peat. Several of the identified degraders, particularly fermenters and potential Fe(III) or humic substance reducers in the oligotrophic peat, represent promising candidates for resolving the origin of excess CO production in peatlands.

Importance: Peatlands are major sources of the greenhouse gas methane (CH), yet in many peatlands, CO production from unresolved anaerobic processes exceeds CH production. Anaerobic degradation produces the precursors of CH production but also represents competing processes. We show that anaerobic degradation leading to high or low CH production involved distinct sets of bacteria. Well-known fermenters dominated in a peatland with high CH production, while novel and unconventional degraders could be identified in a site where CO production greatly exceeds CH production. Our results help identify and assign functions to uncharacterized bacteria that promote or inhibit CH production and reveal bacteria potentially producing the excess CO in acidic peat. This study contributes to understanding the microbiological basis for different levels of CH emission from peatlands.
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http://dx.doi.org/10.1128/AEM.02533-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5288814PMC
February 2017

Study of the effect of the bacterial and fungal communities present in real wastewater effluents on the performance of fungal treatments.

Sci Total Environ 2017 Feb 23;579:366-377. Epub 2016 Nov 23.

Departament d'Enginyeria Química, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain.

The use of the ligninolytic fungi Trametes versicolor for the degradation of micropollutants has been widely studied. However, few studies have addressed the treatment of real wastewater containing pharmaceutically active compounds (PhAC) under non-sterile conditions. The main drawback of performing such treatments is the difficulty for the inoculated fungus to successfully compete with the other microorganisms growing in the bioreactor. In the present study, several fungal treatments were performed under non-sterile conditions in continuous operational mode with two types of real wastewater effluent, namely, a reverse osmosis concentrate (ROC) from a wastewater treatment plant and a veterinary hospital wastewater (VHW). In all cases, the setup consisted of two parallel reactors: one inoculated with T. versicolor and one non-inoculated, which was used as the control. The main objective of this work was to correlate the operational conditions and traditional monitoring parameters, such as laccase activity, with PhAC removal and the composition of the microbial communities developed inside the bioreactors. For that purpose a variety of biochemical and molecular biology analyses were performed: phospholipid fatty acids analysis (PLFA), quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) followed by sequencing. The results show that many indigenous fungi (and not only bacteria, which were the focus of the majority of previously published research) can successfully compete with the inoculated fungi (i.e., Trichoderma asperellum overtook T. versicolor in the ROC treatment). We also showed that the wastewater origin and the operational conditions had a stronger impact on the diversity of microbial communities developed in the bioreactors than the inoculation or not with T. versicolor.
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http://dx.doi.org/10.1016/j.scitotenv.2016.11.088DOI Listing
February 2017

Impacts of forest harvesting on mobilization of Hg and MeHg in drained peatland forests on black schist or felsic bedrock.

Environ Monit Assess 2016 Apr 15;188(4):228. Epub 2016 Mar 15.

Natural Resources Institute Finland, P.O. Box 18, Vantaa, FI-01301, Finland.

Forest harvesting, especially when intensified harvesting method as whole-tree harvesting with stump lifting (WTHs) are used, may increase mercury (Hg) and methylmercury (MeHg) leaching to recipient water courses. The effect can be enhanced if the underlying bedrock and overburden soil contain Hg. The impact of stem-only harvesting (SOH) and WTHs on the concentrations of Hg and MeHg as well as several other variables in the ditch water was studied using a paired catchment approach in eight drained peatland-dominated catchments in Finland (2008-2012). Four of the catchments were on felsic bedrock and four on black schist bedrock containing heavy metals. Although both Hg and MeHg concentrations increased after harvesting in all treated sites according to the randomized intervention analyses (RIAs), there was only a weak indication of a harvest-induced mobilization of Hg and MeHg into the ditches. Furthermore, no clear differences between WTHs and SOH were found, although MeHg showed a nearly significant difference (p = 0.06) between the harvesting regimes. However, there was a clear bedrock effect, since the MeHg concentrations in the ditch water were higher at catchments on black schist than at those on felsic bedrock. The pH, suspended solid matter (SSM), dissolved organic carbon (DOC), and iron (Fe) concentrations increased after harvest while the sulfate (SO4-S) concentration decreased. The highest abundances of sulfate-reducing bacteria (SRB) were found on the sites with high MeHg concentrations. The biggest changes in ditch water concentrations occurred first 2 years after harvesting.
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http://dx.doi.org/10.1007/s10661-016-5210-xDOI Listing
April 2016

Continuous fungal treatment of non-sterile veterinary hospital effluent: pharmaceuticals removal and microbial community assessment.

Appl Microbiol Biotechnol 2016 Mar 6;100(5):2401-15. Epub 2015 Nov 6.

Institut de Química Avançada de Catalunya (IQAC) CSIC, Jordi Girona 18-26, 08034, Barcelona, Spain.

Source point treatment of effluents with a high load of pharmaceutical active compounds (PhACs), such as hospital wastewater, is a matter of discussion among the scientific community. Fungal treatments have been reported to be successful in degrading this type of pollutants and, therefore, the white-rot fungus Trametes versicolor was applied for the removal of PhACs from veterinary hospital wastewater. Sixty-six percent removal was achieved in a non-sterile batch bioreactor inoculated with T. versicolor pellets. On the other hand, the study of microbial communities by means of DGGE and phylogenetic analyses led us to identify some microbial interactions and helped us moving to a continuous process. PhAC removal efficiency achieved in the fungal treatment operated in non-sterile continuous mode was 44 % after adjusting the C/N ratio with respect to the previously calculated one for sterile treatments. Fungal and bacterial communities in the continuous bioreactors were monitored as well.
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http://dx.doi.org/10.1007/s00253-015-7105-0DOI Listing
March 2016

Microform-related community patterns of methane-cycling microbes in boreal Sphagnum bogs are site specific.

FEMS Microbiol Ecol 2015 Sep 27;91(9):fiv094. Epub 2015 Jul 27.

Peatland Ecology Group, Department of Forest Sciences, University of Helsinki, FI-00014, Finland.

Vegetation and water table are important regulators of methane emission in peatlands. Microform variation encompasses these factors in small-scale topographic gradients of dry hummocks, intermediate lawns and wet hollows. We examined methane production and oxidization among microforms in four boreal bogs that showed more variation of vegetation within a bog with microform than between the bogs. Potential methane production was low and differed among bogs but not consistently with microform. Methane oxidation followed water table position with microform, showing higher rates closer to surface in lawns and hollows than in hummocks. Methanogen community, analysed by mcrA terminal restriction fragment length polymorphism and dominated by Methanoregulaceae or 'Methanoflorentaceae', varied strongly with bog. The extent of microform-related variation of methanogens depended on the bog. Methanotrophs identified as Methylocystis spp. in pmoA denaturing gradient gel electrophoresis similarly showed effect of bog, and microform patterns were stronger within individual bogs. Our results suggest that methane-cycling microbes in boreal Sphagnum bogs with seemingly uniform environmental conditions may show strong site-dependent variation. The bog-intrinsic factor may be related to carbon availability but contrary to expectations appears to be unrelated to current surface vegetation, calling attention to the origin of carbon substrates for microbes in bogs.
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http://dx.doi.org/10.1093/femsec/fiv094DOI Listing
September 2015

Microbial ecology in a future climate: effects of temperature and moisture on microbial communities of two boreal fens.

FEMS Microbiol Ecol 2015 Jul 10;91(7). Epub 2015 Jun 10.

Natural Resources Institute Finland (Luke), FI-01370 Vantaa, Finland.

Impacts of warming with open-top chambers on microbial communities in wet conditions and in conditions resulting from moderate water-level drawdown (WLD) were studied across 0-50 cm depth in northern and southern boreal sedge fens. Warming alone decreased microbial biomass especially in the northern fen. Impact of warming on microbial PLFA and fungal ITS composition was more obvious in the northern fen and linked to moisture regime and sample depth. Fungal-specific PLFA increased in the surface peat in the drier regime and decreased in layers below 10 cm in the wet regime after warming. OTUs representing Tomentella and Lactarius were observed in drier regime and Mortierella in wet regime after warming in the northern fen. The ectomycorrhizal fungi responded only to WLD. Interestingly, warming together with WLD decreased archaeal 16S rRNA copy numbers in general, and fungal ITS copy numbers in the northern fen. Expectedly, many results indicated that microbial response on warming may be linked to the moisture regime. Results indicated that microbial community in the northern fen representing Arctic soils would be more sensitive to environmental changes. The response to future climate change clearly may vary even within a habitat type, exemplified here by boreal sedge fen.
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http://dx.doi.org/10.1093/femsec/fiv062DOI Listing
July 2015

Nitric oxide for anammox recovery in a nitrite-inhibited deammonification system.

Environ Technol 2015 27;36(19):2477-87. Epub 2015 Apr 27.

a Institute of Chemistry, University of Tartu , 14a Ravila St., 50411 Tartu , Estonia.

The anaerobic ammonium oxidation (anammox) process is widely used for N-rich wastewater treatment. In the current research the deammonification reactor in a reverse order (first anammox, then the nitrifying biofilm cultivation) was started up with a high maximum N removal rate (1.4 g N m(-2) d(-1)) in a moving bed biofilm reactor. Cultivated biofilm total nitrogen removal rates were accelerated the most by anammox intermediate - nitric oxide (optimum 58 mg NO-N L(-1)) addition. Furthermore, NO was added in order to eliminate inhibition caused by nitrite concentrations (>50 mg [Formula: see text]) increasing [Formula: see text] (2/1, respectively) along with a higher ratio of [Formula: see text] (0.6/1, respectively) than stoichiometrical for this optimal NO amount added during batch tests. Planctomycetales clone P4 sequences, which was the closest (98% and 99% similarity, respectively) relative to Candidatus Brocadia fulgida sequences quantities increase to 1 × 10(6) anammox gene copies g(-1) total suspended solids to till day 650 were determined by quantitative polymerase chain reaction.
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http://dx.doi.org/10.1080/09593330.2015.1034791DOI Listing
September 2016

Start-up of low-temperature anammox in UASB from mesophilic yeast factory anaerobic tank inoculum.

Environ Technol 2015 Jan-Feb;36(1-4):214-25. Epub 2014 Aug 20.

a Institute of Chemistry, University of Tartu , 14a Ravila Rd., Tartu 50411 , Estonia.

Robust start-up of the anaerobic ammonium oxidation (anammox) process from non-anammox-specific seeding material was achieved by using an inoculation with sludge-treating industrial [Formula: see text]-, organics- and N-rich yeast factory wastewater. N-rich reject water was treated at 20°C, which is significantly lower than optimum treatment temperature. Increasing the frequency of biomass fluidization (from 1-2 times per day to 4-5 times per day) through feeding the reactor with higher flow rate resulted in an improved total nitrogen removal rate (from 100 to 500 g m(-3)d(-1)) and increased anammox bacteria activity. As a result of polymerase chain reaction (PCR) tests, uncultured planctomycetes clone 07260064(4)-2-M13-_A01 (GenBank: JX852965) was identified from the biomass taken from the reactor. The presence of anammox bacteria after cultivation in the reactor was confirmed by quantitative PCR (qPCR); an increase in quantity up to ∼2×10(6) copies g VSS(-1) during operation could be seen in qPCR. Statistical modelling of chemical parameters revealed the roles of several optimized parameters needed for a stable process.
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http://dx.doi.org/10.1080/09593330.2014.941946DOI Listing
September 2015

Short-term impacts of energy wood harvesting on ectomycorrhizal fungal communities of Norway spruce saplings.

ISME J 2015 Mar 29;9(3):581-91. Epub 2014 Aug 29.

Department of Biology, University of Oulu, Oulu, Finland.

The increased demand for harvesting energy wood raises questions about its effects on the functioning of the forest ecosystems, soil processes and biodiversity. Impacts of tree stump removal on ectomycorrhizal fungal (EMF) communities of Norway spruce saplings were studied with 454-pyrosequencing in a 3-year field experiment replicated in 3 geographical areas. This is possibly the most thorough investigation of EMF communities associated with saplings grown on sites subjected to energy wood harvesting. To separate impacts of tree stump and logging residue removal on EMF and plant variables, we used three harvesting treatments with increasing complexity from patch mounding alone (P) to patch mounding combined with logging residue removal (RP), and patch mounding combined with both logging residue and stump removal (SRP). Saplings grown in uncut forests (F) served as references for harvesting treatments. A majority of sequences (>92%) and operational taxonomic units (OTUs, 55%) were assigned as EMF. EMF OTU richness, fungal community composition or sapling growth did not differ between harvesting treatments (P, RP and SRP), while EMF OTU richness, diversity and evenness were highest and sapling growth lowest in the undisturbed reference forests (F). The short study period may partially explain the similarities in fungal and sapling variables in different harvesting treatments. In conclusion, our results indicate that neither stump removal nor logging residue removal have significant additional negative impacts on EMF communities or growth of Norway spruce saplings in the short-term compared with the impacts of more conventional harvesting methods, including clear cutting and patch mounding.
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http://dx.doi.org/10.1038/ismej.2014.154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4331576PMC
March 2015

Peatland succession induces a shift in the community composition of Sphagnum-associated active methanotrophs.

FEMS Microbiol Ecol 2014 Jun 11;88(3):596-611. Epub 2014 Apr 11.

Southern Finland Regional Unit, Finnish Forest Research Institute, Vantaa, Finland.

Sphagnum-associated methanotrophs (SAM) are an important sink for the methane (CH4) formed in boreal peatlands. We aimed to reveal how peatland succession, which entails a directional change in several environmental variables, affects SAM and their activity. Based on the pmoA microarray results, SAM community structure changes when a peatland develops from a minerotrophic fen to an ombrotrophic bog. Methanotroph subtypes Ia, Ib, and II showed slightly contrasting patterns during succession, suggesting differences in their ecological niche adaptation. Although the direct DNA-based analysis revealed a high diversity of type Ib and II methanotrophs throughout the studied peatland chronosequence, stable isotope probing (SIP) of the pmoA gene indicated they were active mainly during the later stages of succession. In contrast, type Ia methanotrophs showed active CH4 consumption in all analyzed samples. SIP-derived (13)C-labeled 16S rRNA gene clone libraries revealed a high diversity of SAM in every succession stage including some putative Methylocella/Methyloferula methanotrophs that are not detectable with the pmoA-based approach. In addition, a high diversity of 16S rRNA gene sequences likely representing cross-labeled nonmethanotrophs was discovered, including a significant proportion of Verrucomicrobia-related sequences. These results help to predict the effects of changing environmental conditions on SAM communities and activity.
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http://dx.doi.org/10.1111/1574-6941.12327DOI Listing
June 2014

Methanotrophy induces nitrogen fixation during peatland development.

Proc Natl Acad Sci U S A 2014 Jan 30;111(2):734-9. Epub 2013 Dec 30.

Forest Sciences, University of Helsinki, FI-00014, Helsinki, Finland.

Nitrogen (N) accumulation rates in peatland ecosystems indicate significant biological atmospheric N2 fixation associated with Sphagnum mosses. Here, we show that the linkage between methanotrophic carbon cycling and N2 fixation may constitute an important mechanism in the rapid accumulation of N during the primary succession of peatlands. In our experimental stable isotope enrichment study, previously overlooked methane-induced N2 fixation explained more than one-third of the new N input in the younger peatland stages, where the highest N2 fixation rates and highest methane oxidation activities co-occurred in the water-submerged moss vegetation.
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http://dx.doi.org/10.1073/pnas.1314284111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3896166PMC
January 2014

Methane-cycling microbial communities and methane emission in natural and restored peatlands.

Appl Environ Microbiol 2012 Sep 29;78(17):6386-9. Epub 2012 Jun 29.

General Microbiology, Department of Biosciences, University of Helsinki, Helsinki, Finland.

We addressed how restoration of forestry-drained peatlands affects CH(4)-cycling microbes. Despite similar community compositions, the abundance of methanogens and methanotrophs was lower in restored than in natural sites and correlated with CH(4) emission. Poor establishment of methanogens may thus explain low CH(4) emissions on restored peatlands even 10 to 12 years after restoration.
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http://dx.doi.org/10.1128/AEM.00261-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3416597PMC
September 2012

Water dispersal of methanotrophic bacteria maintains functional methane oxidation in sphagnum mosses.

Front Microbiol 2012 23;3:15. Epub 2012 Jan 23.

Finnish Forest Research Institute, Southern Finland Regional Unit Vantaa, Finland.

It is known that Sphagnum associated methanotrophy (SAM) changes in relation to the peatland water table (WT) level. After drought, rising WT is able to reactivate SAM. We aimed to reveal whether this reactivation is due to activation of indigenous methane (CH(4)) oxidizing bacteria (MOB) already present in the mosses or to MOB present in water. This was tested through two approaches: in a transplantation experiment, Sphagna lacking SAM activity were transplanted into flark water next to Sphagna oxidizing CH(4). Already after 3 days, most of the transplants showed CH(4) oxidation activity. Microarray showed that the MOB community compositions of the transplants and the original active mosses had become more similar within 28 days thus indicating MOB movement through water between mosses. Methylocystis-related type II MOB dominated the community. In a following experiment, SAM inactive mosses were bathed overnight in non-sterile and sterile-filtered SAM active site flark water. Only mosses bathed with non-sterile flark water became SAM active, which was also shown by the pmoA copy number increase of over 60 times. Thus, it was evident that MOB present in the water can colonize Sphagnum mosses. This colonization could act as a resilience mechanism for peatland CH(4) dynamics by allowing the re-emergence of CH(4) oxidation activity in Sphagnum.
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http://dx.doi.org/10.3389/fmicb.2012.00015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263434PMC
October 2012

The ectomycorrhizal fungus Tricholoma matsutake is a facultative saprotroph in vitro.

Mycorrhiza 2012 Aug 18;22(6):409-18. Epub 2011 Oct 18.

Finnish Forest Research Institute, PL 18, FI-01301, Vantaa, Finland.

Tricholoma matsutake is an economically important ectomycorrhizal fungus of coniferous woodlands. Mycologists suspect that this fungus is also capable of saprotrophic feeding. In order to evaluate this hypothesis, enzyme and chemical assays were performed in the field and laboratory. From a natural population of T. matsutake in southern Finland, samples of soil-mycelium aggregate (shiro) were taken from sites of sporocarp formation and nearby control (PCR-negative) spots. Soil organic carbon and activity rates of hemicellulolytic enzymes were measured. The productivity of T. matsutake was related to the amount of utilizable organic carbon in the shiro, where the activity of xylosidase was significantly higher than in the control sample. In the laboratory, sterile pieces of bark from the roots of Scots pine were inoculated with T. matsutake and the activity rates of two hemicellulolytic enzymes (xylosidase and glucuronidase) were assayed. Furthermore, a liquid culture system showed how T. matsutake can utilize hemicellulose as its sole carbon source. Results linked and quantified the general relationship between enzymes secreted by T. matsutake and the degradation of hemicellulose. Our findings suggest that T. matsutake lives mainly as an ectomycorrhizal symbiont but can also feed as a saprotroph. A flexible trophic ecology confers T. matsutake with a clear advantage in a heterogeneous environment and during sporocarp formation.
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http://dx.doi.org/10.1007/s00572-011-0416-9DOI Listing
August 2012

Tricholoma matsutake dominates diverse microbial communities in different forest soils.

Appl Environ Microbiol 2011 Dec 7;77(24):8523-31. Epub 2011 Oct 7.

Finnish Forest Research Institute, Vantaa Research Unit, PL 18, FI-01301 Vantaa, Finland.

Fungal and actinobacterial communities were analyzed together with soil chemistry and enzyme activities in order to profile the microbial diversity associated with the economically important mushroom Tricholoma matsutake. Samples of mycelium-soil aggregation (shiro) were collected from three experimental sites where sporocarps naturally formed. PCR was used to confirm the presence and absence of matsutake in soil samples. PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting and direct sequencing were used to identify fungi and actinobacteria in the mineral and organic soil layers separately. Soil enzyme activities and hemicellulotic carbohydrates were analyzed in a productive experimental site. Soil chemistry was investigated in both organic and mineral soil layers at all three experimental sites. Matsutake dominated in the shiro but also coexisted with a high diversity of fungi and actinobacteria. Tomentollopsis sp. in the organic layer above the shiro and Piloderma sp. in the shiro correlated positively with the presence of T. matsutake in all experimental sites. A Thermomonosporaceae bacterium and Nocardia sp. correlated positively with the presence of T. matsutake, and Streptomyces sp. was a common cohabitant in the shiro, although these operational taxonomic units (OTUs) did not occur at all sites. Significantly higher enzyme activity levels were detected in shiro soil. These enzymes are involved in the mobilization of carbon from organic matter decomposition. Matsutake was not associated with a particular soil chemistry compared to that of nearby sites where the fungus does not occur. The presence of a significant hemicellulose pool and the enzymes to degrade it indicates the potential for obtaining carbon from the soil rather than tree roots.
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http://dx.doi.org/10.1128/AEM.05839-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3233081PMC
December 2011

The role of Sphagnum mosses in the methane cycling of a boreal mire.

Ecology 2010 Aug;91(8):2356-65

Department of Forest Ecology, FI-00014 University of Helsinki, Finland.

Peatlands are a major natural source of atmospheric methane (CH4). Emissions from Sphagnum-dominated mires are lower than those measured from other mire types. This observation may partly be due to methanotrophic (i.e., methane-consuming) bacteria associated with Sphagnum. Twenty-three of the 41 Sphagnum species in Finland can be found in the peatland at Lakkasuo. To better understand the Sphagnum-methanotroph system, we tested the following hypotheses: (1) all these Sphagnum species support methanotrophic bacteria; (2) water level is the key environmental determinant for differences in methanotrophy across habitats; (3) under dry conditions, Sphagnum species will not host methanotrophic bacteria; and (4) methanotrophs can move from one Sphagnum shoot to another in an aquatic environment. To address hypotheses 1 and 2, we measured the water table and CH4 oxidation for all Sphagnum species at Lakkasuo in 1-5 replicates for each species. Using this systematic approach, we included Sphagnum spp. with narrow and broad ecological tolerances. To estimate the potential contribution of CH4 to moss carbon, we measured the uptake of delta13C supplied as CH4 or as carbon dioxide dissolved in water. To test hypotheses 2-4, we transplanted inactive moss patches to active sites and measured their methanotroph communities before and after transplantation. All 23 Sphagnum species showed methanotrophic activity, confirming hypothesis 1. We found that water level was the key environmental factor regulating methanotrophy in Sphagnum (hypothesis 2). Mosses that previously exhibited no CH4 oxidation became active when transplanted to an environment in which the microbes in the control mosses were actively oxidizing CH4 (hypothesis 4). Newly active transplants possessed a Methylocystis signature also found in the control Sphagnum spp. Inactive transplants also supported a Methylocystis signature in common with active transplants and control mosses, which rejects hypothesis 3. Our results imply a loose symbiosis between Sphagnum spp. and methanotrophic bacteria that accounts for potentially 10-30% of Sphagnum carbon.
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http://dx.doi.org/10.1890/09-1343.1DOI Listing
August 2010

Temperature sensitivity of soil carbon fractions in boreal forest soil.

Ecology 2010 Feb;91(2):370-6

Finnish Environment Institute, Research Programme for Global Change, P.O. Box 140, FI-00251 Helsinki, Finland.

Feedback to climate warming from the carbon balance of terrestrial ecosystems depends critically on the temperature sensitivity of soil organic carbon (SOC) decomposition. Still, the temperature sensitivity is not known for the majority of the SOC, which is tens or hundreds of years old. This old fraction is paradoxically concluded to be more, less, or equally sensitive compared to the younger fraction. Here, we present results that explain these inconsistencies. We show that the temperature sensitivity of decomposition increases remarkably from the youngest annually cycling fraction (Q10 < 2) to a decadally cycling one (Q10 = 4.2-6.9) but decreases again to a centennially cycling fraction (Q10 = 2.4-2.8) in boreal forest soil. Compared to the method used for current global estimates (temperature sensitivity of all SOC equal to that of the total heterotrophic soil respiration), the soils studied will lose 30-45% more carbon in response to climate warming during the next few decades, if there is no change in carbon input. Carbon input, derivative of plant productivity, would have to increase by 100-120%, as compared to the earlier estimated 70-80%, in order to compensate for the accelerated decomposition.
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http://dx.doi.org/10.1890/09-0478.1DOI Listing
February 2010

Quantitative PCR of pmoA using a novel reverse primer correlates with potential methane oxidation in Finnish fen.

Res Microbiol 2009 Dec 23;160(10):751-6. Epub 2009 Sep 23.

Finnish Forest Research Institute, Vantaa Research Unit, Box 18, FI-01301 Vantaa, Finland.

We report a new reverse primer (A621r) for use with A189f in PCR amplification of pmoA alleles in type II methanotrophs. The new primer combination was used to successfully amplify pmoA in peat monolith samples of various depths taken from fen-type peatlands in Finland. In quantitative PCR, pmoA amplicons produced from two sets of three replicate monoliths showed a significant Pearson correlation coefficient (r=0.77 and 0.61) with methane oxidation potential. The maximum methane oxidation potential and number of pmoA amplicons ranged between 8.8-40.5 micromol g (dry weight)(-1) d(-1) and 5.5 x 10(7)-18.7 x 10(7) g (wet weight)(-1), respectively, occurring in depths between 10 and 30 cm beneath the surface in the seven individual monoliths used in this study.
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http://dx.doi.org/10.1016/j.resmic.2009.09.008DOI Listing
December 2009

Archaeal rRNA diversity and methane production in deep boreal peat.

FEMS Microbiol Ecol 2009 Oct 10;70(1):87-98. Epub 2009 Jul 10.

Department of Biological and Environmental Sciences, General Microbiology, University of Helsinki, Helsinki, Finland.

Northern peatlands play a major role in the global carbon cycle as sinks for CO(2) and as sources of CH(4). These diverse ecosystems develop through accumulation of partially decomposed plant material as peat. With increasing depth, peat becomes more and more recalcitrant due to its longer exposure to decomposing processes. Compared with surface peat, deeper peat sediments remain microbiologically poorly described. We detected active archaeal communities even in the deep bottom layers (-220/-280 cm) of two Finnish fen-type peatlands by 16S rRNA-based terminal restriction fragment length polymorphism analysis. In the sediments of the northern study site, all detected archaea were methanogens with Rice Cluster II (RC-II) and Methanosaetaceae as major groups. In southern peatland, Crenarchaeota of a rare unidentified cluster were present together with mainly RC-II methanogens. RNA profiles showed a larger archaeal diversity than DNA-based community profiles, suggesting that small but active populations were better visualized with rRNA. In addition, potential methane production measurements indicated methanogenic activity throughout the vertical peat profiles.
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http://dx.doi.org/10.1111/j.1574-6941.2009.00738.xDOI Listing
October 2009
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