Microbiology- Environmental Influences

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Title: Environmental Influences Objectives -Determine optimal growth temperature for a bacterium -Learn about the effect of salt concentration on the growth of bacteria. -To determine how the different pH values affect the population growth of bacteria. -To determine how the different temperatures affect the growth of bacteria. -To differentiate between oxygen requirements using anaerobic culture media Introduction Microbes are exposed to a wide variety of environmental factors in addition to nutrients. For most microbes, environmental factors fundamentally affect the function of metabolic enzymes. Thus, survival in a changing environment is largely a matter of whether the enzyme systems of microorganisms can adapt to alterations in their habitat. This experiment was designed to test the rate of growth of microorganism in four different conditions. Microbes do not have the ability, as we do, to regulate temperature. Their temperature matches that of their environment. All organisms have a range of temperatures within which they can survive. Every organism also has an optimum temperature at which it grows best. The temperature limits on growth are dictated by the proteins in the cell and the structure of the cell membrane. Microorganisms are classified by their optimum growth temperature. Microorganisms can be classified as psychrophiles, mesophiles, thermophiles, and hyperthermophiles, and each classification has its own set of special characteristics. If a microbes cell is in a solution in which the concentration of solutes is higher than that found in the cell, cellular water passes through the cytoplasmic membrane in the direction of the high solute concentration. During the loss of water, the cytoplasmic membrane collapses away from the cell wall, which is called plasmolysis. Extreme halophiles (sometimes called obligate halophiles) are organisms

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