1) Product yield in anaerobic digestion
Anaerobic digestion of volatile acids by methane bacteria is represented by the equation:
CH3COOH + NH 3 --9 biomass + CO 2 + H20 + CH 4.
(acetic acid) (methane)
The composition of methane bacteria is approximated by the empirical formula CH1.4Oo.40N0.20. For each kg acetic acid consumed, 0.67 kg CO 2 is evolved. How does the yield of methane under these conditions compare with the maximum possible yield?


2) Detecting unknown products
Yeast growing in continuous culture produce 0.37 g biomass per g glucose consumed; about 0.88 g 0 2 is consumed per g cells formed. The nitrogen source is ammonia, and the biomass composition is CH1.7900.56N0.17. Are other products also synthesised?

3) Oxygen demand for production of recombinant protein
Production of recombinant protein by a geneticallyengineered strain of Escherichia coli is proportional to cell growth. Ammonia is used as nitrogen source for aerobic respiration of glucose. The recombinant protein has an overall formula CHI.5500.31N0.25. The yield ofbiomass from glucose is measured at 0.48 g g-1; the yield of recombinant protein from glucose is about 20% that for cells.
(a) How much ammonia is required?
(b) What is the oxygen demand?
(c) If the biomass yield remains at 0.48 g g- l, how much different are the ammonia and oxygen requirements for wild-type E. coliunable to synthesise recombinant protein?