chapt06 - Part II MICROBIAL NUTRITION, GROWTH, AND CONTROL...

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Part II MICROBIAL NUTRITION, GROWTH, AND CONTROL 6 Microbial Nutrition CHAPTER OVERVIEW This chapter describes the basic nutritional requirements of microorganisms. Cells must have a supply of raw materials and energy in order to construct new cellular components. This chapter also describes the processes by which microorganisms acquire nutrients and provides information about the cultivation of microorganisms. CHAPTER OBJECTIVES After reading this chapter you should be able to: list the ten elements that microorganisms require in large amounts (macronutrients/macroelements) and the six elements that they require in smaller amounts (micronutrients/trace elements) list the major nutritional categories and give the source of carbon, energy, and electrons for each compare and contrast the various processes (passive diffusion, facilitated diffusion, active transport, group translocation) by which cells can obtain nutrients from the environment describe the various types of culture media for microorganisms (defined/synthetic, complex, selective, differential) and tell how each is normally used in the study of microorganisms describe the techniques used to obtain pure cultures (spread plate, streak plate, pour plate) CHAPTER OUTLINE I.Elements of Life A. Macroelements, also known as macronutrients (C, O, H, N, S, P, K, Ca, Mg, Fe), are required by microorganisms in relatively large amounts B. Trace elements or micronutrients (Mn, Zn, Co, Mo, Ni, Cu) are required in trace amounts by most cells and are often adequately supplied in the water used to prepare media or in the regular media components C. Other elements may be needed by particular types of microorganisms II.Carbon, Hydrogen, Oxygen, and Electrons A. The requirements for carbon, hydrogen, and oxygen are often satisfied together by the same molecule B. Heterotrophs use reduced, preformed organic molecules (usually from other organisms) as carbon sources C. Autotrophs use carbon dioxide as their sole or principal carbon source III.Nutritional Types of Microorganisms A. All organisms need a source of energy and electrons 1. Energy a. Phototrophs use light as their energy source b. Chemotrophs obtain energy from the oxidation of organic or inorganic compounds 57
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2. Electrons a. Lithotrophs use reduced inorganic compounds as their electron source b. Organotrophs use reduced organic compounds as their electron source B. Most microorganisms can be categorized as belonging to one of four major nutritional types depending on their sources of carbon, energy, and electrons: 1. Photolithoautotrophs (photoautotrophs) 2. Chemoorganoheterotrophs (chemoheterotrophs) 3. Photoorganoheterotrophs 4. Chemolithoautotrophs C. Some organisms show great metabolic flexibility and alter their metabolic patterns in response to environmental changes; mixotrophic organisms combine lithotrophic and heterotrophic metabolic processes, relying on inorganic energy sources and organic carbon sources IV.Nitrogen, Phosphorus, and Sulfur
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chapt06 - Part II MICROBIAL NUTRITION, GROWTH, AND CONTROL...

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