Streak plate – the original culture is directly diluted across an agar surface using an inoculating loop ... If this procedure is performed correctly, a number of isolated colonies will grow that will ...

Thus organisms capable of lactose fermentation such as Escherichia coli, form bright pinky-red colonies (plate pictured on the left here). MacConkey agar is commonly used to differentiate between the ...

However, when grown on agar in a Petri dish, each individual cell divides multiple times to form a visible colony. If we count the number of individual colonies of bacteria on the plates ...