Diauxic growth or diauxie is any cell growth characterized by cellular growth in two phases, and can be illustrated with a diauxic growth curve. Diauxic growth, meaning double growth, is caused by the presence of two sugars on a culture growth media, one of which is easier for the target bacterium to metabolize. The preferred sugar is consumed first, which leads to rapid growth, followed by a lag phase. During the lag phase the cellular machinery used to metabolize the second sugar is activated and subsequently the second sugar is metabolized.
This can also occur when the bacterium in a closed batch culture consumes most of its nutrients and is entering the stationary phase when new nutrients are suddenly added to the growth media. The bacterium enters a lag phase where it tries to ingest the food. Once the food starts being utilized, it enters a new log phase showing a second peak on the growth curve.
A refers to the growth curve generated by an organism which has two growth peaks. The theory behind the diauxic growth curve stems from Jacques Monod's Ph.D. research in 1940.
A simple example involves the bacterium (E. coli), the best understood bacterium. The bacterium is grown on agrowth media containing two types of sugars, one of which is easier to metabolize than the other (for example glucose and lactose). First, the bacterium will metabolize all the glucose, and grow at a higher speed. Eventually, wh