Introductory Microbiology

Di-auxic growth

• : In a medium containing two carbon sources bacteria such as E. coli display a growth curve which is called diauxic. J. Monod, about 35 years ago observed this phenomenon when he grew E. coli in a medium containing glucose and lactose. Under these conditions, glucose is first utilized and after the exhaustion of glucose, lactose is utilized. In between a short lag period is seen. This led him to conclude that bacteria preferentially utilize certain carbon substrates.
• Di-auxic growth can be obtained by using any pair of carbon compounds as long as other nutrients are not limiting.