Recombinant protein production is carried out in a batch production system using Escherichia coli bacteria. The volume of the reactor is 200 liters. 20 g cells are inoculated into nutrient medium containing 6% (w/v) glucose. The maximum specific growth rate is 0.95 h-1, and the biomass production efficiency from glucose is 0.75 g/g. a)Calculate the time required to switch to the stationary phase. b)Calculate the final cell concentration if 80% of glucose is spent.