This is the day to day problem of a medical microbiology laboratory: the "tube containing a liquid nutrient medium" in the real world could, for example, represent blood culture bottles (aerobic or anaerobic). The basic process is as follows: a loop is first flamed to ensure sterility and then used to transfer a small portion of bacterial-laden liquid media to the agar medium by streaking it across the surface of a sterile petri dish. The dish is then covered, inverted, and placed in an appropriate incubator. When colonies begin to form on the surface of the agar plate, individual colonies can be taken up using the sterile loop for analysis or further propagation. The assumption is that a single colony represents growth from a single bacterium.
