A Screening of a GadA- $\beta$ -Gal Fusion Protein in E $\beta$

Multiple Choice

A screening of a GadA- $\beta$ -gal fusion protein in E. coli is performed on medium containing X-Gal. White and blue colonies are observed after incubation. Which of the following statements is NOT true regarding blue/white selection?

A) Blue colonies result from X-Gal hydrolyzed by the fusion protein's $\beta$ -galactosidase moiety.
B) White colonies result from cells with a disrupted gene encoding a positive regulator of GadA.
C) Galactose released from X-Gal hydrolysis does not contribute to a colony's blue color.
D) White colonies indicate hydrolysis of X-Gal catalyzed by $\beta$ -galactosidase.
E) All of the above.