152 research outputs found
Labelling plants in the Chernobyl way: A new 137Cs and 14C foliar application approach to investigate rhizodeposition and biopore reuse
No full textImproved water and rice residue managements reduce greenhouse gas emissions from paddy soil and increase rice yields
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Development of micro-zymography: Visualization of enzymatic activity at the microscopic scale for aggregates collected from the rhizosphere
No full textAbstract
Aims
Visualization of enzymatic activity links microbial functioning to localization in heterogeneous soil habitats. To assess enzymatic reactions in soil thin layer at the microscopic level, we developed a micro-zymography approach and tested it by visualization of the potential activity of phosphomonoesterase for aggregates collected from the rhizosphere of
Zea mays
L.
Methods
We evaluated micro-zymography by applying fluorogenically-labeled substrate i) on individual soil aggregates freshly sampled from the rhizosphere, ii) on thin layers of aggregates (≈ 500 µm) saturated with substrate to assess the dynamics of phosphomonoesterase activity, and iii) on maize roots under laser scanning microscope upon the identified hotspots by membrane-based zymography.
Results
We found super transparent silicon as the most appropriate fixative to prevent sample drying. We optimized microscope settings to eliminate the soil auto-fluorescence. The fluorescent signal shifted from the free liquid phase towards the aggregate boundaries within 30 min after substrate addition and was finally detectable at the surface of a few aggregates. This was probably due to higher microbial abundance and enzymatic activity on the soil aggregates compared to the liquid phase. The enzymatic activity appeared patchy at the aggregate and root surfaces indicating heterogeneous distribution of hotspots.
Conclusions
The methodology including calibration, sample preparation, fixation, and monitoring was developed. The novel membrane-free micro-zymography approach is a promising tool to identify functional specificity and niche differentiation on roots and soil aggregates. This approach revealed unexplained complexity of competing processes (biochemical, hydrolytic, and physical) due to differently charged reaction products and enzyme-clay complexes.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Helmholtz-Zentrum für Umweltforschung GmbH - UF
Compound‐specific 13 C stable isotope probing confirms synthesis of polyhydroxybutyrate by soil bacteria
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Biopore history determines the microbial community composition in subsoil hotspots
No full textBiopores are hotspots of nutrient mobilisation and shortcuts for carbon (C) into subsoils. C processing relies on microbial community composition, which remains unexplored in subsoil biopores. Phospholipid fatty acids (PLFAs; markers for living microbial groups) and amino sugars (microbial necromass markers) were extracted from two subsoil depths (45-75 cm ; 75-105 cm) and three biopore types: (I) drilosphere of Lumbricus terrestris L., (II) 2-year-old root biopores and (III) 1.5-year-old root biopores plus six 6 months of L. terrestris activities. Biopore C contents were at least 2.5 times higher than in bulk soil, causing 26-35 times higher I pound PLFAs g(-1) soil. The highest I pound PLFAs were found in both earthworm biopore types; thus, the highest soil organic matter and nutrient turnover were assumed. I pound PLFAs was 33% lower in root pores than in earthworm pores. The treatment affected the microbial community composition more strongly than soil depth, hinting to similar C quality in biopores: Gram-positives including actinobacteria were more abundant in root pores than in earthworm pores, probably due to lower C bioavailability in the former. Both earthworm pore types featured fresh litter input, promoting growth of Gram-negatives and fungi. Earthworms in root pores shifted the composition of the microbial community heavily and turned root pores into earthworm pores within 6 months. Only recent communities were affected and they reflect a strong heterogeneity of microbial activity and functions in subsoil hotspots, whereas biopore-specific necromass accumulation from different microbial groups was absent.German Research Foundation [DFG KU 1184/29-1, INST 186/1006-1
Erosion proxies in an exotic tree plantation question the appropriate land use in Central Chile
No full textVegetation transition from meadow to forest reduces priming effect on SOM decomposition
No full texthttp://dx.doi.org/10.13039/501100001655 Deutscher Akademischer Austauschdiensthttp://dx.doi.org/10.13039/501100004543 China Scholarship Counci
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