Chapter 4: Microbial Growth and Its Control Flashcards
A microbial sample is unable to grow in a normal batch culture but does not grow in an anaerobic environment either. This organism is a ___________
microaerophile
What is true of the cardinal temperatures?
The optimal temperature is closer to the maximum temperature than the minimum temperature.
What happens if an obligate anaerobe such as Clostridium is exposed to air?
It cannot grow, although it may survive.
A microbe that lives in a hydrothermal vent at 109 degrees celsius is a _________
hyperthermophile
Most organisms that live in aerobic environments require catalase and __________
superoxide dismutase
A researcher carefully combines 10 grams of glucose, 8 grams of buffer components and 4 grams each of six specific nutrients before adding them to 900 ml of distilled water. This medium is best described as a ________
defined medium
A researcher realizes that the cytoplasm of a microbe has a pH of 6.0. Knowing that a microbe is an acidophile, she injects acid into the cytoplasm to lower the pH to 4.0. What do you predict will happen?
THe microbe will probably die because its internal pH is too low
What is one of the major elements that is required by cells, making up most of their dry weight?
Sulfur (S)
Why do facultative anaerobes grow better when oxygen is present?
They can use aerobic respiration, which produces more adenosine triphosphate (ATP) than fermentation or anaerobic respiration
Do disinfectants work the same when used in standard, real-world situations as they do in the laboratory?
No, because organic material may protect microbes from exposure.
A thioglycolate broth culture that contains a thin band without growth, a thin band with growth, and then a large region without growth that extends to the bottom of the tube contains an ___________
microaerophile
a test tube of bacteria is allowed to sit undisturbed in the lab for an extended time , and then the growth is estimated using turbidity measurements. Do you predict that this estimate will be accurate?
no, because it is likely that a biofilm has formed
Why do defined culture media often contain the components of a buffer, such as K2HPO4 and KH2PO4?
Microbes are sensitive to pH.
A researcher obtains a microbe from a very hot environment with an average temperature of about 101 degrees Celsius. What can he be most confident is true?
It is classified in domain Archaea
What is one way in which microbes in a biofilm may differ based on their location?
Access to nutrients may vary by location