PER ISTALTIC PUMP
(A)
(I N LINE)
(B) ELEC TROLYSIS
' PUMP'
VOLTAGE
SOURCE
Experimental Manipulation of Model Ecosystems
303
FILTERED AIR
LIGHT RING
r------t1--------...4===~ OVERFLOW TUBE
RESERVOIR
CHEMOSTAT
CULTURE
CHAMBER
OVERFLOW
RESERVOIR
Figure 23.1. Chemostat continuous culture apparatus. in which the nutrient media of the reservoirs are
supplied by a peristaltic pump (A) or by pressure of gas generated by electrolysis (S).
chamber constant. The initial culture should be 81 of natural water from a local pond or
stream containing a full complement of the organisms present.
Operate the chemos tat for this exercise for three weeks at a flow rate of 160 ml/h. The
dilution rate. D (i.e., number of volumes of medium passed through the culture chamber
in 1 h), can be calculated by D = R/V, where R = flow rate in ml/h and V = volume (ml)
of culture. Its reciprocal, l/D, is the mean residence time (i.e., average time a water
molecule or suspended particle spends in the culture chamber).
When the chemostat is in operation, it is possible to calculate the theoretical
concentration of the medium created in the culture chamber after any given number of
hours:
C t = Co + [C~R -Co J [1- e-(t-to)R/V J
(1)
where C( = outflow concentration at time t, Co = concentration at time zero (to).
Cj = concentration of inflow, R = flow rate (ml/h), V = volume of culture chamber (ml),
and to = time 0; initiation of experiment.
Sample calculation: Given Co = 0, t = 115 h, R = 160 ml/h, V = 8000 ml, and
Cj = 155,ug P/I:
C = 0 + [(15?)(160) - oJ [1 _ e-(115)(160/8000)]
(
160
C t = (155)(1 - e-2.3), where e-2.3 = 0.100259
C t = 139.5,ug P/I created in chamber after 115 h
(A)
(I N LINE)
(B) ELEC TROLYSIS
' PUMP'
VOLTAGE
SOURCE
Experimental Manipulation of Model Ecosystems
303
FILTERED AIR
LIGHT RING
r------t1--------...4===~ OVERFLOW TUBE
RESERVOIR
CHEMOSTAT
CULTURE
CHAMBER
OVERFLOW
RESERVOIR
Figure 23.1. Chemostat continuous culture apparatus. in which the nutrient media of the reservoirs are
supplied by a peristaltic pump (A) or by pressure of gas generated by electrolysis (S).
chamber constant. The initial culture should be 81 of natural water from a local pond or
stream containing a full complement of the organisms present.
Operate the chemos tat for this exercise for three weeks at a flow rate of 160 ml/h. The
dilution rate. D (i.e., number of volumes of medium passed through the culture chamber
in 1 h), can be calculated by D = R/V, where R = flow rate in ml/h and V = volume (ml)
of culture. Its reciprocal, l/D, is the mean residence time (i.e., average time a water
molecule or suspended particle spends in the culture chamber).
When the chemostat is in operation, it is possible to calculate the theoretical
concentration of the medium created in the culture chamber after any given number of
hours:
C t = Co + [C~R -Co J [1- e-(t-to)R/V J
(1)
where C( = outflow concentration at time t, Co = concentration at time zero (to).
Cj = concentration of inflow, R = flow rate (ml/h), V = volume of culture chamber (ml),
and to = time 0; initiation of experiment.
Sample calculation: Given Co = 0, t = 115 h, R = 160 ml/h, V = 8000 ml, and
Cj = 155,ug P/I:
C = 0 + [(15?)(160) - oJ [1 _ e-(115)(160/8000)]
(
160
C t = (155)(1 - e-2.3), where e-2.3 = 0.100259
C t = 139.5,ug P/I created in chamber after 115 h