Ecoenzymatic Stoichiometry and Ecological Theory
Tóm tắt
The net primary production of the biosphere is consumed largely by microorganisms, whose metabolism creates the trophic base for detrital foodwebs, drives element cycles, and mediates atmospheric composition. Biogeochemical constraints on microbial catabolism, relative to primary production, create reserves of detrital organic carbon in soils and sediments that exceed the carbon content of the atmosphere and biomass. The production of organic matter is an intracellular process that generates thousands of compounds from a small number of precursors drawn from intermediary metabolism. Osmotrophs generate growth substrates from the products of biosynthesis and diagenesis by enzyme-catalyzed reactions that occur largely outside cells. These enzymes, which we define as ecoenzymes, enter the environment by secretion and lysis. Enzyme expression is regulated by environmental signals, but once released from the cell, ecoenzymatic activity is determined by environmental interactions, represented as a kinetic cascade, that lead to multiphasic kinetics and large spatiotemporal variation. At the ecosystem level, these interactions can be viewed as an energy landscape that directs the availability and flow of resources. Ecoenzymatic activity and microbial metabolism are integrated on the basis of resource demand relative to environmental availability. Macroecological studies show that the most widely measured ecoenzymatic activities have a similar stoichiometry for all microbial communities. Ecoenzymatic stoichiometry connects the elemental stoichiometry of microbial biomass and detrital organic matter to microbial nutrient assimilation and growth. We present a model that combines the kinetics of enzyme activity and community growth under conditions of multiple resource limitation with elements of metabolic and ecological stoichiometry theory. This biogeochemical equilibrium model provides a framework for comparative studies of microbial community metabolism, the principal driver of biogeochemical cycles.
Từ khóa
Tài liệu tham khảo
Allison SD, 2004, Biotropica, 36, 285
Berg G, 2010, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration
Bremner JM, Mulvaney RL. 1978. Urease activity in soils. See Burns 1978, pp. 149–96
Burns RG, 1978, Soil Enzymes
Characklis WG, 1990, Biofilms: A Basis for an Interdisciplinary Approach
Decho AW, 1990, Oceanogr. Mar. Biol. Annu. Rev., 28, 73
Dick R, 2012, Methods of Soil Enzymology.
Hoppe HG. 1991. Microbial extracellular enzyme activity: a new key parameter in aquatic ecology. See Chróst 1991, pp. 60–83
Kahkonen MA, 2001, Boreal Environ. Res., 6, 19
Karner M, 1995, Microb. Ecol., 30, 143
Kaziev FKH, 1975, Biol. Nauki, 10, 121
Marzluf GA, 1997, Microbol. Mol. Biol. Rev., 61, 17
McLaren AD. 1978. Kinetics and consecutive reactions of soil enzymes. See Burns 1978, pp. 97–116
Michaelis L, 1913, Biochemische Z., 49, 333
Münster U. 1991. Extracellular enzyme activity in eutrophic and polyhumic lakes. See Chróst 1991, pp. 96–122
Overbeck J, 1975, Verh. Int. Vereinigung Theor. Angew. Limnol., 19, 2600
Overbeck J. 1991. Early studies on ecto- and extracellular enzymes in aquatic environments. See Chróst 1991, pp. 1–5
Pamer E, 2011, Int. J. Environ. Res., 5, 891
Ramirez-Martinez JR, 1966, Enzymologia, 31, 23
Sinsabaugh RL, Carreiro MM, Alvarez S. 2002. Enzyme and microbial dynamics during litter decomposition. See Burns 2002, pp. 249–66
Skujiņš J. 1978. History of abiontic soil enzyme research. See Burns 1978, pp. 1–49
Speir TW, Ross DJ. 1978. Soil phosphatases and sulphatase. See Burns 1978, pp. 197–250
Sterner RW, 2002, Ecological Stoichiometry: The Biology of Elements from Molecules to the Biosphere
Trasar-Cepeda C, 2011, Soil Enzymology in the Recycling of Organic Wastes and Environmental Restoration
Wang G, Post WM, Mayes MA. 2012a. Development of microbial-enzyme-mediated decomposition model parameters through steady-state and dynamic analyses. Ecol. Appl. In press. (DOI:10.1890/12-0681.1)
Wetzel RG, 1981, Verhandlungen Int. Vereinigung Theor. Angwandte Limnol., 21, 337
Wetzel RG. 1991. Extracellular enzymatic interactions: storage, redistribution and interspecific communication. See Chróst 1991, pp. 6–28
Zeglin LH, 2007, Oecologia, 296, 65