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CHAPTER 7 Elements of Microbial Nutrition, Ecology, and Growth Chapter Overview ?Microbes exist in every known natural habitat on earth. ?Microbes show enormous capacity to adapt to environmental factors. ?Factors that have the greatest impact on microbes are nutrients, temperature, pH, amount of available water, atmospheric gases, light, pressure, and other organisms. ?Nutrition involves absorbing required chemicals from the environment for use in metabolism. ?Autotrophs can exist solely on inorganic nutrients, while heterotrophs require both inorganic and organic nutrients. ?Energy sources for microbes may come from light or chemicals. ?Temperature adaptations may be at cold, moderate, and hot temperatures. ?Oxygen and carbon dioxide are primary gasses used in metabolism. ?Transport of materials by cells involves movement by passive or active mechanisms across the cell membrane. ?The water content of the cell versus its environment dictates the osmotic adaptations of cells. ?Microbes interact in a variety of ways with one another and with other organisms that share their habitats. ?The pattern of population growth in simple microbes is to double the number of cells in each generation. ?Growth rate is limited by lack of nutrients and buildup of waste products. Microbial Nutrition 1.1Chemical Analysis of Microbial Cytoplasm (P188 Table7.2) 1.2Sources of Essential Nutrients P189 Microorganisms require about ten elements in large quantities, because they are used to construct carbohydrates, lipids, proteins, and nucleic acids. Several other elements are needed in very small amounts and are parts of enzymes and cofactors. Carbon Sources (inorganic or organic) heterotroph or autotroph Hot and cold Salt, Acidity, Alkalinity Other Frontiers to Conquer Nitrogen Sources Oxygen Sources Hydrogen Sources Phosphorus Sources Sulfur Sources Other Nutrients Important in Microbial Metabolism Macronutrients大量营养元素 95% or more of cell dry weight is made up of a few major elements: