What is the advantage of using starter cultures for growing bacteria?

Question

Many DNA isolation and protein expression protocols contain instructions to use a starter culture of E. coli that is then used to inoculate the main culture. What are the advantages of using starter cultures compared to just let the bacteria grow in the same medium for a longer time? When should one use starter cultures and when can one safely skip that first culture?

Answer 1

The most significant reason starter cultures are used is to increase the number of bacteria. If starter cultures are not used and you allow the medium to sit longer, the bacteria may stop multiplying. This will in turn cause fewer bacterial colonies for the experiment, which will negatively affect your experiment.

The only way this could be skipped is if you are following an approved method for your experiment and/or have ran this by your PI/mentor/instructor.