Question

Common aseptic transfers and inoculation methods

1. Considering the cultures used to inoculate each medium in this exercise, how many different microbial types should you expect to see on/in each medium? Explain your answer

Streak plate methods of isolation

1. Did you achieve isolation using the quadrant streak? If so in which streak (1,2,3,4) did it occur? If you did not achieve isolation , what might you do differently next time to improve your results?

Colony morphology

1. A description of colony morphology provides important information about an organism. What other colony features should you include ?

2. Three critical aspects of a description of bacterial growth are colony size, color and shape. At least three other important factors- not descriptions of the organism itself-typically are included when describing bacterial growth. What are they and why are they important..

Answer 1

The first three questions cannot be answered with the provided data. They require lab generated data. So I am answering the last question:

Three important factors to describe bacterial growth are:

1) Nutrient content of the culture medium. There are some nutrients, knowm as growth factors, that a cell must contain in order to grow but which it is unable to synthesize, so they need to be supplied as nutrients.

2)pH. Microbes have different pH tolerance ranges, so the pH of the medium will influence the kind of microbes that will grow and their growth speed. Most pathogenic bacteria grow best in pH 7.2-7.4.

3)Temperature. Most bacteria are mesophilic. Mesophilic bacteria grow best at 30-37°C. Optimum temperature for growth of common pathogenic bacteria is 37°C. Bacteria of a species will not grow but may remain alive at a maximum and a minimum temperature.