Question

what is the importance of identifying unknown bacteria in general? paragraph 1
describe the general strategy involved in identifying unknown strains? paragraph 2

Answer 1

Bacteria are present all over the environment as well as inside the body of various organisms. They constitute a large domain of prokaryotic organisms. There are approximately 5*10³⁰ bacteria on earth. There are a lot of bacterial cells residing within the human body. Bacterial cells can either be useful or be pathogenic. Since we encounter bacteria everywhere, it is important to identify them, as they can be the cause for any disease, or just to test if certain food is safe to eat, or simply to know the different organisms in the ecosystem. Hence it is important to identify an unknown bacterial strain.

General methods to identify an unknown strain of bacteria:

1. Culture morphology: A pure culture contains only one type of an organism. The form, elevation, margin, surface, optical characterisation and pigmentation of your colony can describe it. Some strains of bacteria have unique characteristics for their colony while some strains share common features. Hence this alone can not help us in identifying the strain. But it can always be used as the first step.
2. Cell morphology: Put the unknown sample under a microscope and check the morphology of the cell. Look if it can be placed under round coccus, rod shaped bacillus, comma shaped vibrio or spiral shaped spirochete. If it falls under none of these, then make a not of the shape of the cells.
3. Staining: Gram stain can be used to identify if the strain is gram positive( with a thicker peptidoglycan layer that retains the primary stain) or is a gram negative one (which takes the secondary stain of iodine).

With these general initial steps, we can identify the shape, characteristics of culture and if they are gram positive or negative in nature. Further by growing them along with other known bacterial strains, we can check if they have growth promoting or inhibiting properties against that known strain. One can also test the sample for different known bacterial byproducts. Also as a final step DNA sequencing and comparing it with the sequence of a known sample, we can get further information of the unknown strain.