You are given a mixed culture of an aerobic mesophile an ana

You are given a mixed culture of an aerobic mesophile, an anaerobic mesophile, and a microareophilic mesophile. How could you separate the three bacteria into pure cultures?

Solution

The nature of microbes depends upon their ability to survive in aerobic environment. Based upon their requirements for oxygen, the microbes can be aerobic or anaerobic mesophile i.e. those which require normal oxygen concentration and do not require oxygen for respiration and survive in moderate temperatures, respectively. Also, the microbes can be microaerophilic mesophiles in nature i.e. they require only limited amount of oxygen for respiration and survival in moderate temperatures.

Thus, keeping this information in mind, the microbes can be experimentally separated from each other by following steps:

After the plates have grown in a streak culture for atleast 24 hours, the colonies surviving in these respective culture can be picked up, serially diluted and re-plated in fresh plates for atleast 2-3 times. After 3-4 generations, a pure culture of three types can be obtained following above given experimental conditions:

Thus, by providing optimum conditions to each of these types of microbes, a pure culture can be obtained after a few generations.