DIAUXIC GROWTH

 DIAUXIC GROWTH

• Diauxic growth or Diauxie or Diphasic growth is the cell growth characterized by cellular growth in two phases, and can be illustrated with a Diauxic growth curve.
• This Diauxic growth was discovered and named Diauxie in the early 1940s by the French Biochemist Jacques Monod.
• 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. 

• A simple example involves the bacterium Escherichia coli. The Escherichia coli is grown on a growth 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, when all the Glucose has been consumed, the bacterium will begin the process of expressing the genes to metabolize the Lactose. This will only occur when all Glucose in the media has been consumed.