The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of

Options

A. Inactivation of glycosidase enzyme in recombinant bacteria
B. Non-recombinant bacteria containing beta- galactosidase
C. Insertional inactivation of alpha-galactosidase in non- recombinant bacteria
D. Insertional inactivation of alpha-galactosidase in recombinant bacteria

Answer

B

Explanation

The vector is inserted into a competent host cell viable for transformation which are selected in the presence of X-gal. Cells transformed with vectors containing recombinant DNA will produce white colonies as they are not able to metabolized colourless X – gal. While cells transformed with non – recombinant plasmids metabolized form and insoluble product (5 – bromo 4 – chloroindole) which is bright blue and functions as an indicator to form blue colonies