Answer :
A bacterial strain with a mutant lac repressor unable to bind allolactose would be non-inducible regarding the lac operon, not producing the necessary enzymes for lactose catabolism regardless of lactose presence.
If a bacterial strain has a mutant lac repressor that cannot bind to allolactose, this strain would likely be unable to induce the lac operon. Typically in the lac operon system, allolactose acts as an inducer by binding to the repressor, causing a conformational change that prevents the repressor from binding to the operator site on the operon.
When this interaction is inhibited, the lac repressor remains bound to the operator, preventing RNA polymerase from transcribing the genes necessary for lactose metabolism.
Consequently, the enzymes required for lactose catabolism (e.g., β-galactosidase, permease, and transacetylase) are not produced, making this bacterial strain 'non-inducible' with respect to the lac operon. Thus, the presence or absence of lactose will not affect the repression of the operon, and lactose metabolism will be impeded.
