Biochemical Reactions - A First Look
($„), 0.728; biomass (x), 2.36; ethanol
8.85; glycerol (pg), 2.39. The
production is measured by a
photoacustic method. The CO: concentration in the effluent gas (in the head space) is found to be 2.88
vol %. On a flow-meter the total gas flow (30°C, latm) is determined to 0.25 L min'1. vgf is assumed to be
equal to vg.
Use the data to set up a carbon balance. Show that the data are not consistent, and calculate the
yield coefficient of a missing metabolite.
Calculate the degree of reduction of the missing metabolite. In your opinion what is the source of
Problem 3.5 Production of poly P-hydroxy butyrate (PHB)
. (1997) studied the formation of PHB by the bacterium
continuous stirred tank reactor operated at steady state. When growing under N-limitation but with an
excess of the carbon source the organism can build up a large carbon storage that can be used to support
active growth when, or if the N-limitation is lifted. This is part of the clean-up cycle in waste water
treatment plants, but PHB has an independent and increasing interest as a biodegradeable polymer - in
competition with particularly poly-lactide. Although PHB is a part of the biomass it can just as well be
regarded as a metabolic product. Its formula is
CH^jOoj per carbon atom. The remainder of the
biomass (the “active” biomass) has the formula
per carbon atom. The organism uses
acetic acid, CH
COOH as carbon and energy source. It grows aerobically, and some C 0
The result of two experiments, one with N-limitation and one with C-limitation are given below.
Dilution rate and
m g L 1)
Production rates in mg L'lh'‘
■^hac = 70
D = 0A
$Nm ~ 10.5_______________
For each of the two experiments determine the yield coefficients in the black box model
0(H A c) -
YsxX + YipP + YK
H20 = 0
For each of the two experiments calculate thye exit concentrations of
when there is no
in the feed. Also calculate the inlet concentrations of acetic acid and ammonia.
Could any single kinetic expression describe the results of both experiments?