Hi there,

I guess you are observing a diauxic growth because of the presence of at least two carbon sources in your culture media. After the exhaust of the preferential carbon source during the first part of the growth, cells have to adapt in order to use the second carbon source (lag phase) and then grow again. For more info: https://en.wikipedia.org/wiki/Diauxic_growth

Dear Dominique

Great Thanks for this information, in fact, I am using LB broth for doing the growth curve experiment. Thanks again