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 morphology refers 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
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 of Acinetobacter on MacConkey agar plate