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 ...

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 ...

and lactose broth and agar slants for the completed test. In this procedure, as practiced in our laboratory, we discarded as negative at each step all tubes and plates which we know by previous ...