Question

1. Did you find similarities among the different bacterial cultures colony morphology?

2. What are some other ways to differentiate bacteria, if the the colony morphology is similar?

Answer 1

1. Colony morphology is basically the colony structure or the colony characteristics that are visibly seen directly i.e colony size, shape, and the individual colony is a mass of microorganism that has been generated from a single mother cell. So, the colonies that belong to different bacterial strains, different species, or different genera are not similar in appearance, they look different i.e their characteristics are different from one another. However, there are different types of bacteria that have the same morphology. So, we cannot rely purely on the colony morphology to identify a particular strain of bacteria.

2. Cell morphology basically includes size which can be small, large, medium or pinpoint-sized colonies, shape (cocci shaped, bacilli shaped, spiral-shaped), then surface area i.e some appear smooth, some appear rough, some appear wavy or wrinkled, then colony's edges or margins like margins of the colonies can be smooth, filamentous (filament like), curled (concentric), lobate (lobe like structure), or undulate (wavy like).

Bacteria with similar morphology can also be distinguished by their colour (like P.aerugenusa produces green coloured colony while M.tuberculosis produces buff coloured colony) and pigmentation. They can also be differentiated based on their elevations like some have convex elevations, some have concave elevations, others have flat, while others have umbonate elevations, crateriform elevations, pulvinate elevations.

Other way to differentiate is depending on their opacity like colonies can be translucent i.e clear, they can be opaque i.e not very clear like and others can be iridescent i.e shiny ones.

Also, we can differentiate by the colonies texture I.e whether the colonies are dry, moist, or viscid or mucoid (mucus-like), how the cells are arranged (in diploid, or in clusters, or in tetrads or in long chains or as a single chain)

Apart from these, to differentiate gram staining can be performed, certain biochemical tests can be done, there are antibiotic specific susceptibility tests, molecular techniques can be performed like polymerase chain reaction (PCR), nucleic acid hybridization, DNA probe tests.

Thus, these are some of the ways to differentiate the bacteria, if the colony morphology is similar.