Lecture 6 microbial ecology 2011 - Microbial ecology abundance distribution and interactions Microbes are everywhere Microbes are diverse Microbes act

Lecture 6 microbial ecology 2011 - Microbial ecology...

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Microbial ecology abundance, distribution and interactions Microbes are everywhere Microbes are diverse Microbes act cooperatively
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Microbes are everywhere Different habitats provide varied physical attributes and nutrients. -selection The microbial community varies depending on the habitat. Community vs individual species
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Microbial Communities There is often interaction among species Investigative techniques Confocal scanning laser microscopy Flourescent probes allow you to identify groups and individual species DNA arrays Genes vs expression
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4 Microbes in Ecosystems Microbes absorb energy Microbes assimilate minerals CO 2 , N 2 Producers: Algae, Phytoplankton, Bacteria Microbes at all levels of food web Consumers: Bacteria, Archaea, Eukaryotes Decomposers: Fungi, Viruses Importance varies in different habitats
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Think microscopically
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Environmental example Soil
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Soil Particle Silt, sand, rock Organic matter Microbes Aerobic and anaerobic zones
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What’s contributing to microbial diversity? Large amount of complex organics Dead plants and animals, waste Moderate temperature (4- 45°C) Moderate pH Heterogeneous environment Gradients of chemicals (oxygen) Two general layers Surface Subsurface
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Microbial Diversity of Soil Dizzying numbers 1-10 billion cells per gram of soil 3,000 to 10 6 species Most are uncharacterized!
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Symbiosis The living together of two different kinds of organisms Mutualistic- both partners benefit Parasitic – one partner benefits at the expense of the other Term commonly used to denote mutualistic associations
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Simple Interactions Microbes live in communities and metabolize complex compounds in a cooperative manner, i.e., rumen Microbial communities make environments more hospitable for others, i.e. Some microbes metabolize end products that reach inhibitory concentrations.
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Syntrophy Syntrophy is an interaction between organisms that combine their metabolic capabilities to catabolize substances that individuals cannot catabolize alone. The cell-cell interactions follow favorable thermodynamics even though individual reactions may be unfavorable. Some microbes that form syntrophic interactions are able to metabolize various pollutants in the environment (PCBs and aromatic compounds).
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Example: Saccharomyces cerevisiae deacidifies the environment allowing P seudomonas putida to thrive. Grapes contain a high concentration of glucose. P. putida can initially grow but because it ferments carbohydrates and acidifies the environment, it cannot survive for extended periods of time.
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  • Spring '09
  • kaspar/escalnte/downs
  • Bacteria, partner, Rhizobium, Syntrophy

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