Question

Background Colony: A colony, in microbiology, is a visible cluster or mass of microorganisms (such as bacteria or fungi) that has grown and multiplied on a solid agar medium. Each colony represents a population of genetically identical microbial cells that originated from a single cell or a small group of cells. Colony formation is an essential step in the isolation and identification of microorganisms. Colony morphologyrefers to the visible characteristics of a bacterial or fungal colony when grown on a solid agar medium. It includes features such as size, shape, color, texture, and edge appearance. Each type of microorganism may exhibit distinct colony morphologies, aiding in their identification and classification. It should be noted that when a microbiologist examines an agar plate and determines that mixed bacterial

types are present, it is actually mixed bacterial colonial types (morphotypes) that are being observed. These visually distinctive colonies often represent different species (or even genera), but they may also represent phenotypic variants of a single genotypic organism. Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 7th.
Wolters Kluwer; 2017. Question In diagnostic microbiology and in order to save time, how do microbiologists decide whether two morphotypes on the same plate belong to the same strain? I'm not talking about great differences in morphologies as Lactose fermenters vs Non-Lactose fermenters on MacConkey agar, but ones like these: The center in Type A is purple while the center in Type B is pink. Pure culture ofAcinetobacteron MacConkey agar plate.

Answer 1

Colonial morphology, which includes texture, color, size, shape, and other characteristics, is used by microbiologists to identify and differentiate bacterial species, aiding in the isolation of pure cultures.

Step-by-step explanation:

In diagnostic microbiology, colonial morphology is crucial for identifying bacterial species due to differences in appearance of colonies originating from distinct bacterial strains. When examining colonies on an agar plate, microbiologists describe the morphology by noting several characteristic features of each colony. These include but are not limited to texture, color, size, shape, margin, and elevation. Notably, color variations such as a purple center in Type A or a pink center in Type B can provide significant insight into identifying whether colonies represent different strains or are phenotypic variants of the same organism. Utilizing a colony counter or dissecting microscope can assist in observing finer details. Describing these aspects, specifically looking for consistency across multiple isolated colonies, allows for a preliminary identification and helps decide if two morphotypes on the same plate might belong to the same strain, which is particularly valuable when isolating a pure culture.