Briefly describe how you would screen E. coli mutants that cannot utilize lactose as an energy source. (You are given a test tube containing E.

5.    Briefly describe how you would screen E. colimutants that cannot utilize lactose as an energy source. (You are given a test tube containing E. coligrown under full nutrition, a spreader, filter paper, Petri plates with agar gel containing various nutrients, and an incubator. There are three kinds of Petri plates provided: agar gel was made with either inorganic salt + glucose [plate A], or inorganic salt + lactose [plate B], or inorganic salt only [plate C]).