Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure because it requires simultaneous plating on two plates - Biology - Biotechnology Principles and Processes

Question

Selection of recombinants due to inactivation of antibiotics is a
cumbersome procedure because it requires simultaneous plating on
two plates having different antibiotics Therefore, alternative
selectable markers have been developed which differentiate
recombinants from non-recombinants on the basis of their ability to
produce colour in the presence of a chromogenic substrate WHAT DOES
IT MEAN ?

Asandra Andrews · Accepted Answer

After the insertion of alien DNA, the recombinant plasmids lose
the antibiotic resistance, that is they get inactivated Whereas the
non recombinants still have both the antibiotic resistance
genes
So now we know the di​fference between the recombinants
and the non-recombinants, but to check this we need to plate these
at the same time in different plates with the different antibiotic
resistance genes
We need to observe what is growing where and what is not
growing so this is quite a tiring or time-consuming procedure
Hence, other selectable markers have been developed which are
much easier to use
Since, they easily differentiate recombinants from the
non-recombinants as the recombinants do not have the ability to
produce colour in presence of a chromogenic substrate
Non-recombinants can produce colour

That is explained in the same paragraph on page 200 of the NCERT
Textbook for Biology Hope this helps :)