EBIO 3400 1st Edition Lecture 9Outline of Last Lecture I. Microbial growthOutline of Current Lecture II. Stages of growth in a batch cultureIII. Normal growth conditionsIV. Other factors affecting microbial growth V. Microbes are commonly classified by their environmental nicheVI. What determines the environmental habitat that a species inhabitsVII. Adaptation to temperatureVIII.Current LectureI. Stages of growth in a batch cultureA. Batch culture: the simplest way to see the effects of a changing environment is toculture bacteria in this - Bacteria in a liquid medium within a closed system (inoculating) - Exponential growth never lasts indefinitely B. Phases of bacterial growth in a typical batch culture1) Lag phase: takes some time for the organism to adjust to their environment and start growing. Can also occur if the organism is being moved to a new medium, coming out of dormancy2) Log phase: grows exponentially3) Stationary phase: where the organism goes through different physiology stages to help them survive i.e forming endospores 4) Death phase: varies on cell to cell depending on how resistant they are II. Normal growth conditions1) Sea level2) Low salt content (0.9% salt)3) Neutral pH4) Temperature: 20-40 deg Celsius- Any ecological niche outside of this criteria are considered extremophiles These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.III. Other factors affecting microbial growth 1) Temperature2) pH3) Oxygen concentration4) Pressure * anything that is going to be off will make it grow smaller What limits exponential growth of microbes?- Predation and parasitism - Competition for nutrients and spaceIV. Microbes are commonly classified by their environmental niche growth temperature Temperature (Degrees Celsius) MicroorganismGrowth above 80 (65-121) HyperthermophileGrowth between 40-80 ThermophileGrowth between 15-45 MesophileGrowth below 15 (0-20) PsychrophileGrowth in high salt Halophile* All of these organisms have membranes and proteins best suited for their temperaturesV. What determines the environmental habitat that a species inhabits like high salt or low pH- One main thing: the tolerance of that organism’s proteins and other macromolecular structures to the physical conditions within that niche - Growth is over quite a large range for temp and enzyme activity- Each species has an optimum temperature of pH that it can live at, if extend more than optimal level then will die off above that maximum - Enzyme response to temperature determines growth response VI. Adaptation to temperature - A bacterial cell’s temperature matches that of its immediate environment- Each organism has an optimum temperature, as well as maxium and minimum temperatures that define its growth limits- Microbes that grow at higher temperatures can typically achieve higher rates of growth (E. Coli)VII. Growth rate and temperature- The typical temperature growth rate range usually spans the organism’s optimal growth temperature by 30-40 degrees - Because of thermodynamic principles End of lecture – Final review session for exam
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