caa a22 4500 605516650 CHVBK 20210128100715.0 cr unu---uuuuu 210128e20150501xx s 000 0 eng 10.1007/s10533-015-0096-1 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0096-1 Particle-associated and cell-free extracellular enzyme activity in relation to nutrient status of large tributaries of the Lower Mississippi River [Elektronische Daten] [Justin Millar, Jason Payne, Clifford Ochs, Colin Jackson] Microbial extracellular enzyme activity is responsible for much of the carbon and nutrient cycling in freshwaters, and logically there should a relationship between the chemical properties of a system and its enzymatic profile. To evaluate this concept, we surveyed extracellular enzyme activity in five large rivers (the Upper Mississippi, Missouri, Ohio, Tennessee, and Arkansas) of the Mississippi River Basin, one of the world's largest river systems. The rivers drain areas of different climate, physiography, and land use, and differ in their physicochemical properties. Despite differences in nutrient concentrations, there were no consistent differences in enzyme activity between the five rivers, with as much variation in activity between sites on the same river as among different rivers. Enzymatic profiles were dominated by leucine aminopeptidase, phosphatase, and β-glucosidase, and appreciable enzymatic activity was still present following the removal of particles (3-micron filtration) or cells (0.22-micron filtration). The proportion of particle- or cell- associated enzymatic activity contributing to overall activity varied between enzymes, being higher for β-glucosidase, leucine aminopeptidase, and N-acetyl-β-D-glucosaminidase than for sulfatase or cellobiohydrolase. Dissolved elemental stoichiometry suggested that bacterioplankton in all rivers were limited by C overall, with P also being more limiting than N. While regional-scale patterns in enzyme activity in large rivers may indicate anthropogenic influences, this study demonstrates that finer-scale variation, such as between sites on the same river, or between particles and free-living bacterioplankton, may be equally as important. Springer International Publishing Switzerland, 2015 Bacterioplankton nationallicence Extracellular enzyme activity nationallicence Large rivers nationallicence Mississippi River nationallicence Nutrient status nationallicence Millar Justin Department of Biology, University of Mississippi, 38655, University, MS, USA aut Payne Jason Department of Biology, University of Mississippi, 38655, University, MS, USA aut Ochs Clifford Department of Biology, University of Mississippi, 38655, University, MS, USA aut Jackson Colin Department of Biology, University of Mississippi, 38655, University, MS, USA aut Biogeochemistry Springer International Publishing 124/1-3(2015-05-01), 255-271 0168-2563 124:1-3<255 2015 124 10533 https://doi.org/10.1007/s10533-015-0096-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0096-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Millar Justin Department of Biology, University of Mississippi, 38655, University, MS, USA aut NATIONALLICENCE 700 1- Payne Jason Department of Biology, University of Mississippi, 38655, University, MS, USA aut NATIONALLICENCE 700 1- Ochs Clifford Department of Biology, University of Mississippi, 38655, University, MS, USA aut NATIONALLICENCE 700 1- Jackson Colin Department of Biology, University of Mississippi, 38655, University, MS, USA aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 124/1-3(2015-05-01), 255-271 0168-2563 124:1-3<255 2015 124 10533