In most cases, the microorganisms are not growing due to the temperature in the incubation environment being too low. All cultures used in the lesson will grow at ambient temperatures between 21 oC and 25 oC (70 oF and 78 oF) within approximately 1 to 3 days of inoculation. Incubation temperatures lower than 20 oC (68 oF) will significantly increase the amount of time required for culture growth.
For additional information, review the prerequisite “Microbiology Laboratory Preparation” or the Microbiology FAQs document in your course.