Diauxic Growth

Diauxic Growth :

Preferential growth on one carbon source before growth on a second carbon source is called as "Diauxic Growth".

E.coli grow preferentially on glucose when presented with mixtures of glucose and other carbon sources.The bacteria first grow exponentially on glucose, then enter lag period and finally grow exponentially on the second carbon source.

Glucose represses the synthesis of enzymes required to grow on certain alternative carbon sources such as Lactose.Glucose also inhibits the uptake of other sugar source into the cells the result is that growth on the Second Carbon Source does not proceed until the glucose is exhausted from the medium.

Repression of the genes by glucose is called Catabolite repression or 'Glucose Repression'.The inhibition of uptake of a alternative sugars is called as 'Inducer exclusion'.

             Diauxoc Growth Diagram