Pathogenic Microbiology
Lab Sheet # 3 “THIO FLUID”
Objective: Thio fluid is a liquid medium that can be modified to promote growth of a wide variety of
fastidious to non-fastidious organisms. It can be used to illustrate microbial growth representing all
levels of oxygen tolerance. You will be inoculating thio fluid broth to determine the aerotolerance
categories of bacteria. You will also examine the growth of characteristics of four organisms at three
different temperatures and observe the influence of temperature on pigment production.
1. Draw the five categories of aerotolerance: strict aerobe, anaerobe, microaerophilic, facultative
anaerobe, and aerotolerant anaerobe.
2. Why is it important that the thio medium be fresh?
3. Which type of organism would be most likely affected negatively by the use of old media?
4. Why do different temperatures produce different growth rates?
5. In what way(s) could you adjust the incubation temperature to grow an organism at less than its
optimal growth rate?