Microbio Lab 14

Explain the effects of temperatures above the maximum and below the minimum growth temperatures on cellular enzymes.

Enzymes will be denatured above the maximum growth temperature. Below the minimum growth temperature, enzymes are inactivated but not destroyed.

If an organisms grew 20 degrees C, explain how you would determine experimentally whether the organism was a psychrophile or a mesophile.

Incubate culture at 15 and 37 degrees C. If it grows at 37 but not at 15 it is a mesophile. If it grows at 15 but not 37 it is a psychrophile.

Is it possible for thermophilic organisms to induce infections in warm-blooded animals? Explain.

It is not possible for obligate thermophiles to induce infections in warm-blooded animals. The require temperatures that exceed body temperature for growth. Facultative thermophiles can grow at 37 degrees C but their optimum temperature is 45 degrees C which is above body temperature and is unlikely that they would cause infection.

Based on your observations of the S. marcescens and S. cerevisiae cultures, is the optimum growth temperature the ideal temperature for all cell activities? Explain.

The optimum temperature is the temperature at which the rate of reproduction is most rapid. Some cellular activities may not be optimized at the optimum growth temperature. Pigment production in S. marcescens and gas production in S. cerevisiae are not best at the optimum growth temperatures of these organisms.