Each microorganism has a range of temperatures in which it can grow. Within that range, growth rates are generally highest at the organism’s optimum growth temperature.
These limits are approximate. Other environmental conditions, such as nutrient availability and salt concentration, can affect growth. A useful way to picture the relationship is a growth curve: growth rises as conditions approach the optimum, then falls as temperatures move beyond it.
All flashcards
What are the minimum, optimum, and maximum growth temperatures?
The minimum is the lowest temperature permitting survival and replication; the optimum supports the fastest growth; the maximum is the highest temperature permitting growth.
How do unsaturated membrane lipids help psychrophiles?
They help maintain membrane fluidity at low temperatures.
Why can Listeria monocytogenes persist in some refrigerated foods?
It can multiply at refrigeration temperatures and tolerate high salt concentrations.
How can antifreeze proteins and protective solutes help cold-adapted microbes?
They can help protect cells from freezing damage.
Why is Taq polymerase useful in PCR?
It is heat-stable, so it can function through PCR’s high-temperature steps.
Quiz questions
Which growth pattern is typical of thermophiles?Answer: An optimum near 50°C, with growth possible up to about 80°C.
What can high temperatures do to microbial proteins and nucleic acids?Answer: Denature them, disrupting their structures and functions.
How many hydrogen bonds join a guanine–cytosine base pair?Answer: Three hydrogen bonds.
Why can listeriosis be especially serious during pregnancy?Answer: The infection can cross the placenta and harm the fetus.
What is the role of Taq polymerase in PCR?Answer: It copies DNA while remaining functional during high-temperature steps.
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.