escherichia coli colonies as test on macconkey agar plate. focus

agar air aureus background bacteria bacterial bacterium biology biotechnology black blood cell colony color culture danger diagnostic disc fecal ferment food gram growth health healthcare hygiene isolate isolated isolation lab laboratory lactose media medical medicine medium micro microbe microbiology midia negative nonmotile pathogen pathogens petri plate plates red research risk safety saprotrophic science scientific streak test toxic treat urine variable virus yellow