Question

You inoculate a bacterium into three tubes of nutrient broth medium containing added salt: 0.5 percent NaCl, 5 percent NaCl, and 15 percent NaCl. After incubation, you notice significant turbidity in the 15 percent NaCl medium and modest turbidity in the 5 percent NaCl medium. There is no growth in the third tube. This organism would be termed ______.

a. halophilic
b. osmophobic
c. haloduric
d. barophilic

Answer 1

Answer:

a. halophilic

Explanation:

Halophilic microorganisms have an absolute requirement for high salt concentration (NaCl concentration). These microbes grow well under the conditions of higher salt concentration but do not survive the lower salt concentrations. For example, the halobacteria are the archaeans that depend on high NaCl concentrations for growth and do not survive at a concentration below about 1.5 M NaCl.

According to the observations, the bacterium could not grow in the tube having a NaCl concentration of 0.5% but exhibits maximum growth under higher NaCl concentrations (15%). This means that the observed bacterium is a halophile or halophilic microbe.