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Meyer UN, Tischer A, Freitag M, Klaus VH, Kleinebecker T, Oelmann Y, Kandeler E, Hölzel N, Hamer U. Enzyme kinetics inform about mechanistic changes in tea litter decomposition across gradients in land-use intensity in Central German grasslands. Sci Total Environ 2022; 836:155748. [PMID: 35526633 DOI: 10.1016/j.scitotenv.2022.155748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 06/14/2023]
Abstract
Grassland ecosystems provide important ecosystem services such as nutrient cycling and primary production that are affected by land-use intensity. To assess the effects of land-use intensity, operational and sensitive ecological indicators that integrate effects of grassland management on ecosystem processes such as organic matter turnover are needed. Here, we investigated the suitability of measuring the mass loss of standardized tea litter together with extracellular enzyme kinetics as a proxy of litter decomposition in the topsoil of grasslands along a well-defined land-use intensity gradient (fertilization, mowing, grazing) in Central Germany. Tea bags containing either green tea (high-quality litter) or rooibos tea (low-quality litter) were buried in 5 cm soil depth. Litter mass loss was measured after three (early-stage decomposition) and 12 months (mid-stage decomposition). Based on the fluorescence measurement of the reaction product 4-methylumbelliferone, Michaelis-Menten enzyme kinetics (Vmax: potential maximum rate of activity; Km: substrate affinity) of five hydrolases involved in the carbon (C)-, nitrogen (N)- and phosphorus (P)-cycle (β-glucosidase (BG), cellobiohydrolase (CBH), cellotriohydrolase (CTH), 1,4-β-N-acetylglucosaminidase (NAG), and phosphatase (PH)) were determined in tea litter bags and in the surrounding soil. The land-use intensity index (LUI), summarizing fertilization, mowing, grazing, and in particular the frequency of mowing were identified as important drivers of early-stage tea litter decomposition. Mid-stage decomposition was influenced by grazing intensity. The higher the potential activity of all measured C-, N- and P-targeting enzymes, the higher was the decomposition of both tea litters in the early-phase. During mid-stage decomposition, individual enzyme parameters (Vmax of CTH and PH, Km of CBH) became more important. The tea bag method proved to be a suitable indicator which allows an easy and cost-effective assessment of land-use intensity effects on decay processes in manged grasslands. In combination with enzyme kinetics it is an appealing approach to identify mechanisms driving litter break down.
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Affiliation(s)
- Ulf-Niklas Meyer
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany
| | - Alexander Tischer
- Department of Soil Science, Friedrich-Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Martin Freitag
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany
| | - Valentin H Klaus
- Insitute of Agricultural Sciences, Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 2, 8092 Zürich, Switzerland
| | - Till Kleinebecker
- Institute for Landscape Ecology and Resource Management, Giessen University, Heinrich-Buff-Ring 26-32, 35392 Gießen, Germany
| | - Yvonne Oelmann
- Geoecology, Department of Geosciences, University of Tübingen, Rümelinstr. 19-23, 72070 Tübingen, Germany
| | - Ellen Kandeler
- Institute of Soil Science and Land Evaluation, Department of Soil Biology, University of Hohenheim, Emil Wolff Str. 27, 70599 Stuttgart, Germany
| | - Norbert Hölzel
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany
| | - Ute Hamer
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany.
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Chen YC, Chen WT, Liu JC, Tsai LC, Cheng HL. A highly active beta-glucanase from a new strain of rumen fungus Orpinomyces sp.Y102 exhibits cellobiohydrolase and cellotriohydrolase activities. Bioresour Technol 2014; 170:513-521. [PMID: 25164344 DOI: 10.1016/j.biortech.2014.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/31/2014] [Accepted: 08/01/2014] [Indexed: 06/03/2023]
Abstract
A new strain of rumen fungus was isolated from Bos taurus, identified and designated Orpinomyces sp.Y102. A clone, celC7, isolated from the cDNA library of Orpinomyces sp.Y102, was predicted to encode a protein containing a signal peptide (Residues 1-17), an N-terminal dockerin-containing domain, and a C-terminal cellobiohydrolase catalytic domain of glycoside hydrolase family 6. CelC7 was insoluble when expressed in Escherichia coli. Deletion of 17 or 105 residues from the N-terminus significantly improved its solubility. The resulting enzymes, CelC7(-17) and CelC7(-105), were highly active to β-glucan substrates and were stable between pH 5.0 and 11.0. CelC7(-105) worked as an exocellulase releasing cellobiose and cellotriose from acid-swollen Avicel and cellooligosaccharides, and displayed a Vmax of 6321.64μmole/min/mg and a Km of 2.18mg/ml to barley β-glucan. Further, the crude extract of CelC7(-105) facilitated ethanol fermentation from cellulose. Thus, CelC7(-105) is a good candidate for industrial applications such as biofuel production.
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Affiliation(s)
- Yo-Chia Chen
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuehfu Rd., Neipu, Pingtung 91201, Taiwan, ROC
| | - Wan-Ting Chen
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuehfu Rd., Neipu, Pingtung 91201, Taiwan, ROC
| | - Jeng-Chen Liu
- Graduate Institute of Bioresources, National Pingtung University of Science and Technology, 1, Shuehfu Rd., Neipu, Pingtung 91201, Taiwan, ROC
| | - Li-Chu Tsai
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 10608, Taiwan, ROC
| | - Hsueh-Ling Cheng
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuehfu Rd., Neipu, Pingtung 91201, Taiwan, ROC.
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