This lag phase needed for organism to switch over to new carbon source (lactose).
Utilization of glucose and lactose is tightly regulated at gene level. All the genes which are necessary for lactose utilization are arranged in sequence called Lac operon which is regulated by catabolic repression. The following events happen during overall process.
-High level of glucose leads to higher energy production and hence higher ATP and lower AMP. In this scenario there is no free cAMP which binds with CAP( activator protein which facilitates RNA polymerase binding to promoter of Lac operon)and hence there is no expression of the downstream genes.
-In case of lactose, there is high level of cAMP which binds with CAP and induces the expression of Lac operon. Similarly allolactose binds to repressor protein and inhibits its binding to operator site leads to expression of lac operon.
b) Here if we closely look at the data and compare the viable count of aerobic culture it indicates reduction of 1.3X105 cfu/ml when bottle heated at 80C for 10 min. Similarly, for untreated bottle anaerobic viable count is 1.22X105 cfu/ml and if heating have similar effect than there will be complete killing of anaerobic bacteria and we will not get any viable count.