root decomposition
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Forest management practices often severely affect forest ecosystem functioning. Tree removal by clearcutting is one such practice, producing severe impacts due to the total reduction of primary productivity. Here, we assessed changes to fungal community structure and decomposition activity in the soil, roots and rhizosphere of a Picea abies stand for a 2-year period following clearcutting compared to data from before tree harvest. We found that the termination of photosynthate flow through tree roots into soil is associated with profound changes in soil, both in decomposition processes and fungal community composition. The rhizosphere, representing an active compartment of high enzyme activity and high fungal biomass in the living stand, ceases to exist and starts to resemble bulk soil. Decomposing roots appear to separate from bulk soil and develop into hotspots of decomposition and important fungal biomass pools. We found no support for the involvement of ectomycorrhizal fungi in the decomposition of roots, but we found some evidence that root endophytic fungi may have an important role in the early stages of this process. In soil, activity of extracellular enzymes also decreased in the long term following the end of rhizodeposition by tree roots.
- MeSH
- biomasa MeSH
- borovice mikrobiologie MeSH
- ekosystém MeSH
- houby klasifikace genetika růst a vývoj izolace a purifikace MeSH
- kořeny rostlin mikrobiologie MeSH
- mykobiom MeSH
- mykorhiza klasifikace genetika růst a vývoj izolace a purifikace MeSH
- půda chemie MeSH
- půdní mikrobiologie * MeSH
- rhizosféra MeSH
- stromy mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Miscanthus x giganteus is suggested as a good candidate for phytostabilization of metal-polluted soils. Its late harvest in winter generates large amounts of leaf litter on the soil surface. However, little is known about the mobility and the bioavailability of metals following leaf decomposition and the consequences on the succeeding culture. Ex situ artificial aging for 1, 3, and 6 months was conducted with miscanthus leaf fragments incorporated into three agricultural soils displaying a gradient concentration in Cd (0.6, 3.1 and 7.9 mg kg-1), Pb (32.0, 194.6 and 468.6 mg kg-1), and Zn (48.4, 276.3 and 490.2 mg kg-1) to simulate the leaf litter input over 20 years of miscanthus culture. We investigated the impacts on physicochemical and biological soil parameters, CaCl2-extractable metal, and their subsequent ryegrass shoot concentrations, and hence on ryegrass health. The results showed that the amended soils possessed higher pH along with greater available phosphorous and soil organic carbon values. The respiratory activity and microbial biomass carbon in the amended soils increased mainly after 1 month of aging, and decreased afterwards. Despite the higher Pb- and Zn-CaCl2 extractability in the amended soils, the phytoavailability slightly increased only in the most contaminated soils. Moreover, leaf incorporation did not affect the ryegrass biomass, photosynthetic pigment contents, nor the antioxidative enzyme activities. Conclusively, leaf incorporation induced slight variations in soil physicochemical and biological parameters, as well as metal extractability, but not to an extent that might cause a considerable threat to the subsequent culture. Nevertheless, these results are preliminary data that require confirmation by long-term in-situ experimentations as they reflect the modelization of long-term impact of leaf decomposition on soil-plant system.
- MeSH
- biodegradace MeSH
- biologická dostupnost MeSH
- biomasa MeSH
- jílek růst a vývoj metabolismus MeSH
- kořeny rostlin metabolismus MeSH
- látky znečišťující půdu analýza metabolismus MeSH
- lipnicovité * růst a vývoj metabolismus MeSH
- listy rostlin metabolismus MeSH
- půda chemie MeSH
- teoretické modely * MeSH
- těžké kovy analýza metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
The possibility of Miscanthus×giganteus cultivation as an energy crop on the different types of mining rocks was studied. It was revealed that a loess-like loam and red-brown clay with the added black soil were the most suitable for plant growing. The yield of dry above-ground biomass ranged from 4.3 to 6.8 t DM ha-1 after the first year of cultivation and from 8.9 to 9.7 t DM ha-1 after the second year while using these substrates. The application of amendments stimulated the growth and development of plants and increased productivity from 50 to 140%. M.×giganteus showed sufficient tolerance and good enough growth on the geochemically active dark-gray schist clay with yield from 2 to 3 t DM ha-1 after the first year of cultivation already. For plants grown on the different strata of dark-gray schist clay, the thermal decomposition of the biomass took place in four stages in the temperature range from 30 to 640 °C. The samples grown on stratum 0-20 cm showed the highest reactivity with a peak 30.6%/min at 290 °C. There were differences in the concentrations of determined heavy metals: iron, zinc, copper, and lead in the plant tissues depending on the layer depth of dark-gray schist clay from 0 to 20 cm to 40-60 cm. The relatively limited content of heavy metals in the above-ground biomass was due to the preferential accumulation in the roots.
- MeSH
- biologická adaptace * MeSH
- biomasa MeSH
- hornictví * MeSH
- kořeny rostlin chemie růst a vývoj MeSH
- látky znečišťující půdu analýza MeSH
- lipnicovité chemie růst a vývoj MeSH
- půda chemie MeSH
- těžké kovy analýza MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Ukrajina MeSH
Secondary plant metabolites (SPMEs) play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the "secondary compound hypothesis" and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.
- MeSH
- Bacteria klasifikace izolace a purifikace metabolismus MeSH
- biodegradace * MeSH
- látky znečišťující půdu chemie toxicita MeSH
- polychlorované bifenyly toxicita MeSH
- půdní mikrobiologie * MeSH
- rostliny metabolismus mikrobiologie MeSH
- sekundární metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Microbial activity in forest soils is driven by the dynamics of ecosystem processes, largely dependent on trees as the major primary producers. Diurnal variation of root activity, seasonality of photosynthate production or recalcitrance of decomposing plant biomass all affect microbial abundance, composition of their communities and activity. Due to low N content, fungi appear to be the major decomposers of complex plant biomass: litter and deadwood and to largely shape associated bacterial communities and their activity. On the other hand, bacteria are important in decomposition of fungal mycelia and N-cycle processes including N-fixation. Microbial activity is also affected in the short term by climatic events and in the long-term by ecosystem development after disturbances.
Due to the ability of soil bacteria to solubilize minerals, fix N2 and mobilize nutrients entrapped in the organic matter, their role in nutrient turnover and plant fitness is of high relevance in forest ecosystems. Although several authors have already studied the organic matter decomposing enzymes produced by soil and plant root-interacting bacteria, most of the works did not account for the activity of cell wall-attached enzymes. Therefore, the enzyme deployment strategy of three bacterial collections (genera Luteibacter, Pseudomonas and Arthrobacter) associated with Quercus spp. roots was investigated by exploring both cell-bound and freely-released hydrolytic enzymes. We also studied the potential of these bacterial collections to produce enzymes involved in the transformation of plant and fungal biomass. Remarkably, the cell-associated enzymes accounted for the vast majority of the total activity detected among Luteibacter strains, suggesting that they could have developed a strategy to maintain the decomposition products in their vicinity, and therefore to reduce the diffusional losses of the products. The spectrum of the enzymes synthesized and the titres of activity were diverse among the three bacterial genera. While cellulolytic and hemicellulolytic enzymes were rather common among Luteibacter and Pseudomonas strains and less detected in Arthrobacter collection, the activity of lipase was widespread among all the tested strains. Our results indicate that a large fraction of the extracellular enzymatic activity is due to cell wall-attached enzymes for some bacteria, and that Quercus spp. root bacteria could contribute at different levels to carbon (C), phosphorus (P) and nitrogen (N) cycles.
In this work, the binding mechanism of new Polyketide Synthase 13 (Pks13) inhibitors has been studied through molecular dynamics simulation and free energy calculations. The drug Tam1 and its analogs, belonging to the benzofuran class, were submitted to 100 ns simulations, and according to the results obtained for root mean square deviation, all the simulations converged from approximately 30 ns. For the analysis of backbone flotation, the root mean square fluctuations were plotted for the Cα atoms; analysis revealed that the greatest fluctuation occurred in the residues that are part of the protein lid domain. The binding free energy value (ΔGbind) obtained for the Tam16 lead molecule was of -51.43 kcal/mol. When comparing this result with the ΔGbind values for the remaining analogs, the drug Tam16 was found to be the highest ranked: this result is in agreement with the experimental results obtained by Aggarwal and collaborators, where it was verified that the IC50 for Tam16 is the smallest necessary to inhibit the Pks13 (IC50 = 0.19 μM). The energy decomposition analysis suggested that the residues which most interact with inhibitors are: Ser1636, Tyr1637, Asn1640, Ala1667, Phe1670, and Tyr1674, from which the greatest energy contribution to Phe1670 was particularly notable. For the lead molecule Tam16, a hydrogen bond with the hydroxyl of the phenol not observed in the other analogs induced a more stable molecular structure. Aggarwal and colleagues reported this hydrogen bonding as being responsible for the stability of the molecule, optimizing its physic-chemical, toxicological, and pharmacokinetic properties.
- MeSH
- aminokyseliny MeSH
- antituberkulotika chemie farmakologie MeSH
- bakteriální proteiny antagonisté a inhibitory chemie MeSH
- benzofurany chemie farmakologie MeSH
- konformace proteinů MeSH
- molekulární struktura MeSH
- objevování léků MeSH
- polyketidsynthasy antagonisté a inhibitory chemie MeSH
- simulace molekulární dynamiky * MeSH
- simulace molekulového dockingu * MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- vodíková vazba MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Publikační typ
- časopisecké články MeSH
... 2.1 Gauss-Jordan Elimination 41 -- 2.2 Gaussian Elimination with Backsubstitution 46 -- 2.3 L C/Decomposition ... ... Sparse Linear Systems 75 -- 2.8 Vandermonde Matrices and Toeplitz Matrices 93 -- 2.9 Cholesky Decomposition ... ... 100 -- 2.10 Decomposition 102 -- 2.11 Is Matrix Inversion an V3 Process? ... ... Ranking 428 -- 8.5 Selecting the Mth Largest 431 -- 8.6 Determination of Equivalence Classes 439 -- 9 Root ... ... 9.3 Van Wijngaarden-Dekker-Brent Method 454 -- 9.4 Newton-Raphson Method Using Derivative 456 -- 9.5 Roots ...
3rd ed. xxi, 1235 s. : il. ; 27 cm + 1 CD-ROM
- MeSH
- matematické výpočty počítačové MeSH
- matematika MeSH
- numerická analýza pomocí počítače * MeSH
- Publikační typ
- monografie MeSH
Coniferous forests cover extensive areas of the boreal and temperate zones. Owing to their primary production and C storage, they have an important role in the global carbon balance. Forest disturbances such as forest fires, windthrows or insect pest outbreaks have a substantial effect on the functioning of these ecosystems. Recent decades have seen an increase in the areas affected by disturbances in both North America and Europe, with indications that this increase is due to both local human activity and global climate change. Here we examine the structural and functional response of the litter and soil microbial community in a Picea abies forest to tree dieback following an invasion of the bark beetle Ips typographus, with a specific focus on the fungal community. The insect-induced disturbance rapidly and profoundly changed vegetation and nutrient availability by killing spruce trees so that the readily available root exudates were replaced by more recalcitrant, polymeric plant biomass components. Owing to the dramatic decrease in photosynthesis, the rate of decomposition processes in the ecosystem decreased as soon as the one-time litter input had been processed. The fungal community showed profound changes, including a decrease in biomass (2.5-fold in the litter and 12-fold in the soil) together with the disappearance of fungi symbiotic with tree roots and a relative increase in saprotrophic taxa. Within the latter group, successive changes reflected the changing availability of needle litter and woody debris. Bacterial biomass appeared to be either unaffected or increased after the disturbance, resulting in a substantial increase in the bacterial/fungal biomass ratio.
- MeSH
- biomasa MeSH
- brouci fyziologie MeSH
- houby klasifikace izolace a purifikace MeSH
- lesy * MeSH
- půdní mikrobiologie * MeSH
- smrk MeSH
- stromy MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
