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Unformatted text preview: Lecture 14 – BIMM120.SP11 LECTURE 14 – May 17, 2011 Microbial Ecology II: Microbial Biogeochemistry (BLACK = this lecture / BLUE = different lecture / RED = not covered in lecture ) Chapter 23 – Microbial Ecosystems (pp. 673-677) I. Principles of Microbial Ecology 23.1 Ecological Concepts • Ecosystems and Habitats o An ecosystem is the sum total of all the organisms and abiotic factors in a particular environment. o An ecosystem contains many different habitats , portions of the ecosystem best suited to one or a small number of microbial populations • Symbiosis: Parasitism o Symbiosis is a relationship between two or more organisms that share a particular ecosystem o Parasitism is a form of symbiosis in which one member in the relationship is harmed in the process • Symbioses: Mutualism and Commensalism o Mutualism is a symbiotic relationship in which both species benefit o Commensalism is a symbiotic relationship in which one species benefits and the other is neither harmed or helped • Species Diversity and Abundance in Microbial Habitats o The species that inhabit a given ecosystem are those best adapted to growth with the nutrients and conditions that prevail there o Species richness is the total number of different species present o Species abundance is the proportion of each species in the ecosystem o The microbial species richness and abundance of a habitat is a function of the kinds and amounts of nutrients available 23.2 Microbial Ecosystems and Biogeochemical Cycling • Microbial Ecosystems o Metabolically related microbial populations are called guilds , and sets of guilds are called communities • Biogeochemical Cycles o Microorganisms play an essential role in the cycling of elements, including carbon, sulfur, nitrogen, and iron elements. The study of these chemical transformations is called biogeochemistry II. The Microbial Habitat 23.3 Environments and Microenvironments • Environments 1 Lecture 14 – BIMM120.SP11 o Microorganisms are found in every habitat that will sustain life, and the habitats themselves can be exceedingly diverse • The Microorganism and the Microenvironment o Growth of microorganisms depends upon the resources (nutrients) and growth conditions available in their habitat o Differences in the type and quantity of resources and the physiochemical conditions of a habitat define the niche for each particular microorganism...
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