Publications by authors named "Peter Spetz"

5 Publications

  • Page 1 of 1

Surgery was successful--but how did it go for the patient? Experiences from and hopes for the Swedish Perioperative Register.

Eur J Anaesthesiol 2015 Jul;32(7):453-4

From the Swedish Perioperative Register, Uppsala Clinical Research Centre, Uppsala, Sweden.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/EJA.0000000000000283DOI Listing
July 2015

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AEM.05839-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3233081PMC
December 2011

Transformation of Quercus petraea litter: successive changes in litter chemistry are reflected in differential enzyme activity and changes in the microbial community composition.

FEMS Microbiol Ecol 2011 Feb 26;75(2):291-303. Epub 2010 Nov 26.

Laboratory of Environmental Microbiology, Institute of Microbiology of the ASCR, v.v.i., Prague, Czech Republic.

The links among the changes in litter chemistry, the activity of extracellular enzymes and the microbial community composition were observed in Quercus petraea litter. Three phases of decomposition could be distinguished. In the early 4-month stage, with high activities of β-glucosidase, β-xylosidase and cellobiohydrolase, 16.4% of litter was decomposed. Hemicelluloses were rapidly removed while cellulose and lignin degradation was slow. In months 4-12, with high endocellulase and endoxylanase activities, decomposition of cellulose prevailed and 31.8% of litter mass was lost. After the third phase of decomposition until month 24 with high activity of ligninolytic enzymes, the litter mass loss reached 67.9%. After 2 years of decay, cellulose decomposition was almost complete and most of the remaining polysaccharides were in the form of hemicelluloses. Fungi largely dominated over bacteria as leaf endophytes and also in the litter immediately before contact with soil, and this fungal dominance lasted until month 4. Bacterial biomass (measured as phospholipid fatty acid content) in litter increased with time but also changed qualitatively, showing an increasing number of Actinobacteria. This paper shows that the dynamics of decomposition of individual litter components changes with time in accordance with the changes in the microbial community composition and its production of extracellular enzymes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1574-6941.2010.00999.xDOI Listing
February 2011

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1890/09-0478.1DOI Listing
February 2010