Environmental Engineering Reference
In-Depth Information
Table 7.1 Reported random motility and chemotactic sensitivity coefficients for bacteria
under various experimental conditions
Bacterial
strain
Chemoattractant Random
motility
coefficient
(
10
-6
cm
2
/s)
Chemotactic
sensitivity
coefficient
(
10
-4
cm
2
/s)
Experimental
condition
Reference
P. putida
F1
TCE
0.15
0.08
Glass-coated
polystyrene
(250 mm
diameter)
[21]
P. putida
G7
Naphthalene
0.32
0.72 - 0.14
1.3
Bulk liquid
Saturated beads
(50 mm)
[44]
[31]
P. putida
PR2000
3-Chloro
benzene
35 - 2
1.9 - 0.7
Bulk liquid
quartz sand of
diameter:
81 mm
194 mm
326 mm
[48]
0.7
1.6
3.1
Generally, the chemotactic sensitivity parameter is less directly quantified
compared with other model parameters in bacterial transport models, and is
therefore often determined as a fitted parameter. A higher value of
0
represents
greater chemotactic response and thus results in more cell accumulation for
similar concentrations of chemoattractants. Chemotactic sensitivity has units of
distance
2
/time (e.g., cm
2
/s). A comparative list of bacterial random motility and
chemotactic sensitivity coefficients for different bacterial species-chemoattractant
combinations under various experimental condition is given in Table 7.1.
7.4.2 Chemotaxis Receptor Constant (K
d
)
Chemoreceptor half-saturation constant and chemoreceptor binding constant
are terms that are used interchangeably in the literature for the chemotaxis
receptor constant, K
d
. This parameter represents the propensity of bacteria to
bind the attractant and characterizes the binding between attractant molecule
and cell surface receptors, which are responsible for sensing concentration
gradients in the surroundings. The value of this parameter corresponds to an
optimal chemoattractant concentration, where bacteria elicit the strongest
chemotactic response, and hence has units of concentrations (e.g. mM). This
parameter is generally determined from dose-response curves, but can also be
determined as a best fitted model parameter [21].
