Problem 3 (35 points) (a) The parent culture for a bacterial fermentation was grown at 30C in a medium containing 60 g 1 glucose, 20 g protein hydrolysate and 20g yeast extract Samples were inoculated into four subcultures as follows: Subculture B as for parent as for parent culture cuhurs 10 104 D see below as for parent culture 10 10 Medium Inoculum size (cells ml) Inoculumage (h) 6 24 24 24 The medium for subculture contained: 60pl glucose, 10g (NH..SO 1.091 MgSO4, 10 g1 Cat: and assorted trace elements The figure shows the growth of the four subcultures In (cells'ml) Time Give a detailed explanation of the differences in the behaviour of a 6) subcultures A and B subcultures B and D () subcultures B and C In your answer make reference to the biochemical and microbiological mechanisms operating in the various growth phases (9 points. 3 points each) (b) The following data were obtained during batch growth of the bacterium at its optimal temperature on a fully defined synthetic medium with glucose as the growth limiting nutrient Time (from end of lag phase) Biomass concentratio Concentration of glucose 20.0 19.3 186 17.0 0 1 1.5 2 2.5 3 3.3 4 5 6 8 10 15 20 0.1 0:37 0.70 1.32 2.52 4.89 8.99 X 59 7.85 7.35 6.20 5.15 3.45 2.20 92 0 0 0 0 0 0 0 0 (ii) (1) During the exponential phase a small but constant proportion of dead organisms was always observed. How can this observation be explained? (3 points) Use the data to obtain estimates of the maximum specific growth rate on generation time, net yield factor, Yand decay coefficient ko. The organism dies exponentially (13 points (H) If the saturation constant is 20 mg/l and the organism displays Monod kinetics calculate the effluent biomass concentration from a chemostat culture of the organism in the same modium at dilution rates of 0.02 0.6' and Use the constants calculated in part (ii). Interpret your answers. (If you did not complete part (in) carry out the calculation with what you consider to be reasonable estimates of the values of the constants). (10 points +3 bonus points for perfect interpretation)