Question

What would be the phenotype of a null mutation in the V. Fischeri operon LuxI gene (encoding an enzyme that produces the autoinducer) for the quorum sensing.

V. Fischeri would luminesce only if we add autoinducer to the bacteria growth media

V. Fischeri would luminesce all the time, regardless of the number of bacteria

There would be no phenotype

V. Fischeri would luminesce only when the concentration of bacteria is high

Answer 1

Fischeri would luminesce only if we add autoinducer to the bacteria growth media

The population of A.fisheri needs to reach an optimal level to activate the lux operon and stimulate light production. For this the bacteria produces autoinducer from lux1 gene to communicate amongst each other and coordinate behaviors like luminescence, which require large amounts of cells to produce an effect.

If a null mutation is brought about in lux1 gene no autoinducer will be produced and so bacteria will not be able to communicate each other and no luminesence will be produced unless an autoinducer is added .