Exam 4: Dynamics of Microbial Growth

A pure culture in exponential growth phase has a bacterial concentration of 6.4 × 108 cells/ml. If the bacterium has a generation time of 1 h, how long ago was the cell concentration 8.0 × 107 cells/ml?

Bacteria may be stored for several months

Trace elements

Diagnosis of legionellosis depends partly on culture of the causative agent from medical samples. Typically, the organism is grown on buffered charcoal yeast extract (BCYE) agar. What essential component must this medium have to ensure growth of L. pneumophila?

The lag phase of the bacterial growth curve is marked by

Mycobacterium leprae is typically found infecting the ears, toes, and fingers of its host due to its

On HE medium, Shigella species produce blue-green colonies, while Salmonella produces blue-green colonies with a black center. There are two noticeable types of colonies growing on the hektoen enteric (HE) medium in Mrs. Thomas' test. One type of colony is greenish in color. This leads you to conclude that the bacteria in these colonies

Thayer-Martin agar typically contains a combination of antibiotics: vancomycin, colistin, nystatin, and trimethoprim. Please select the TRUE statement.

The optimum pH for growth of most species of bacteria is ________.

Bacteria on fish caught in the Arctic Ocean would

A microbe is discovered growing near a deep sea thermal vent. When researchers bring a sample up to the surface and try to grow it in a lab at room temperature in a normal incubator, they are unsuccessful. Why?

A physician sends a stool sample to your lab, and wants to know if there are lactose fermenting microbes in the sample. How might you determine if these microbes are present or not from this mixed-microbe specimen?

Small organic molecules that must be provided to bacteria in order for them to grow are called

When doing experiments with bacteria,

Agar

Which of the statements about biofilms is true?

You are working in a clinical laboratory in a hospital setting. You're handed a throat swab from a patient. You are told specifically that the physician is only interested in the presence and type of Gram positive cells. Identification isn't the main goal here-just a first step to work towards determining what Gram positive cells might be there. What might you do first to go about working towards this goal?

Which of the following is (are) obligate aerobes?

You are in charge of water quality for your city's water treatment plant. Of the methods at your disposal, which will be the most efficient and cheapest method of determining the number of viable bacteria in the water coming out of your plant?

Organisms that are indifferent to the presence of oxygen and do not use it are