The diauxic growth curve results from the metabolism of:
Historical diauxie experiment performed by Jacques Monod in 1940s used Escherichia coli growing in mixture of glucose and lactose where total sugar limited growth. Growth curve displayed first rapid exponential on glucose, plateau slight lag, second slower exponential on lactose. Reasoning glucose metabolized via Embden Meyerhof pathway directly to pyruvate yielding ATP quickly, while lactose requires uptake via LacY permease and hydrolysis by beta-galactosidase LacZ to glucose plus galactose then Leloir pathway. Regulation ensures lac operon silent during glucose phase due to low cAMP and abs
Ref: NCBI Bookshelf, Molecular Biology of the Cell, Section: The lac operon and diauxic glucose-lactose metabolism.
