Ch6 - Microbial Nutrition Nutritional Requirements...

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Unformatted text preview: Microbial Nutrition Nutritional Requirements Microelements Also called trace elements Enzyme co-factors: Mn, Co, Zn, Mo, Ni, Cu Growth factors Organic compounds unable to be synthesizd by an organism Vitamins Amino acids Purines/pyrimidines Macroelements Structural: C, H, O, N, P, S Catalytic activity & structure stabilizers: K, Ca, Mg, Fe FEED ME! Carbon, Energy & Electron Sources Terms are combined to describe an organisms complete nutritional type: (not biosynthesized) (biosynthesized) Modified from: http://www.tutorvista.com/biology/photoautotrophic-bacteria Nutritional Types Heterotrophs: Energy and/or electrons may also be derived from the organisms carbon source Autotrophs: CO 2 cannot supply energy itself, so a light or inorganic chemical source is necessary; inorganic chemical may provide electrons in addition to energy Nutritional Types (cont.) Metabolic flexibility in purple nonsulfur bacteria: O 2 at normal levels: follow chemoorganoheterotrophy O 2 absent: follow photoorganoheterotrophy O 2 at low levels: follow a mix of both pathways Gain energy from both light and organic chemicals Carbon and e- still come from organic molecules Some can grow as photolithoautotrophs Hydrogen used as e-donor Nutrient Acquisition Requires passage from the environment through the cytoplasmic membrane Abundant vs. scarce Diffusion: Molecules in constant motion Approaches equilibrium distribution of molecules: homeostasis Membranes block diffusion of some molecules http://arditobook.pbworks.com/w/page/11348839/Diffusion Nutrient Transport Mechanisms 1. Passive diffusion 1. Facilitated diffusion 1. Active transport 1. Group translocation P D L ine P D L ine F D L ine F D L ine A T L ine A T L ine G T L ine G T L ine Passive Diffusion Movement from [higher] to [lower] Used for small molecules like O 2 and CO 2 Facilitated Diffusion Carrier proteins required for transport Movement from [higher] to [lower] Saturable: Rate of transport is dependent on [substance] vs. [carriers] Analogy: 50,000 fans enter through 12 gates Facilitated Diffusion...
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This note was uploaded on 09/06/2011 for the course MIBO 3500 taught by Professor Dustman during the Spring '09 term at University of Georgia Athens.

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Ch6 - Microbial Nutrition Nutritional Requirements...

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