Colony Morphology Lab Report

This lab experiment was conducted in order to identify and confirm the presence of three types of organism within an unknown broth culture. The organism that were being tested fall under the categories of gram-positive, gram-negative paracolons, and gram-negative coliform. Gram positive organism are known to have thick cell wall made up of peptidoglycan, which are cross-link sugar chains with peptide bonds (Carson 13). Gram-positive bacteria are found within the phylum Firmicuites (Slonczewski & Foster 94). While gram-negative, have thin layers of one or two peptidoglycan cell wall, this type of bacteria are found within the phylum Proteobacteria (Slonczewaki & Foster). The gram positive and negative characteristic derived from a staining technique that was developed by Hans

Individual colonies are better to work with because the organism can be aseptically transferred to another media, to create a pure culture. This helps narrow down specifically the type of organism of interest (Carson 19). During the culturing process, there are a lot of information that can help deduce the type of organism that are cultured. Some of the characteristic that are used in the identification of cultured organism are known as colony morphology (Carson 20). Colony morphology take in consideration the following characteristic of the culture: Size (small, medium, large), pigment (coloration), optical properties (opaque, translucent, transparent), surface (shiny, smooth, and mucoid) form (circular, irregular, and rhizoid), margin (lobate, undulate, filamentous or serrate), and elevation (flat, raised, umbonate, or convex) (Carson 20). In a more microscopic level, cellular characteristic may apply to the individual cell within a colony, otherwise known as cellular morphology. The agar plate were used during this experiment have selective and differential properties that help to differentiate between organism. A selective media will actively select for or against a particular