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7: Growth

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    Chapter 7 BSC 3271 Learning Outcomes


    • Define doubling (generation) time.
    • Calculate population size and doubling time (generation time) given the appropriate information.
    • Given a description of the ingredients required in a growth medium for an organism, determine whether the organism needs any growth factors and what in the medium is a growth factor; define growth factor.
    • Recognize the phases of the closed system growth curve and describe the physiological condition of cells and population dynamics at each phase
    • Given data on population size at various time points, generate a growth curve and determine doubling (generation) time from the resulting graph.
    • Describe under what kinds of conditions endospores form and germinate as well as the purpose of endospores.
    • Identify the two genera of bacteria which can form endospores.
    • Describe the mechanisms by which environmental factors affect the growth rate of microbes, particularly temperature, salinity, and oxygen.
    • Provide the terms that describe organisms that thrive under various environmental conditions presence/absence of oxygen, high/low temperature, high salt,      high/low pH.

    Control of Microbial Growth

    • Define the suffixes -cidal and -static.
    • Identify major targets of physical and chemical disinfection and sterilization and explain why disruption of each will cause cell death.
    • Distinguish between disinfection and sterilization.
    • Describe how exposure time, microbial load, presence of spores or other resistant forms, and type of antimicrobial process (microbistatic vs. microbicidal) influence the effectiveness of disinfection or sterilization techniques.
    • Describe the difference in effectiveness between moist heat and dry heat  in killing microbes.
    • Describe the effects of cold and dessication on cells.
    • Explain how the following kill cells: ionizing radiation, UV (non-ionizing) radiation, surfactants (specifically quaternary ammonium compounds), chlorine and iodine compounds (halogens), alcohol, hydrogen peroxide, and heavy metals.
    • Identify which physical and chemical methods can (practically) be used to sterilize.
    • Describe how filtration can be used for sterilization
    • Analyze a situation to identify the most suitable disinfection/sterilization techniques.

    Thumbnail: "Klebsiella pneumoniae on C.L.E.D. Agar - detail" by Nathan Reading is licensed under CC BY-NC-ND 2.0