Its a presentation describing how thermophillic bacteria grow in continuous culture.
It consists basic information about continous culture and two research papers.
2. Bacterial Growth
o most lab organisms are grown in a batch
culture
closed system
new materials are not added
waste products are not removed
under these conditions bacteria
populations follow distinct patterns of
growth.
Algae batch cultures
3. Continuous Culture
continuous culture is maintained by-
nutrients must be continually supplied
end products must be removed
exponential growth phase maintained
Continuous culture in lab
4. Growth in Batch Culture
“Growth” is generally used to refer
to the acquisition of biomass leading
to cell division, or reproduction.
5. Bacterial Growth Curve:
laboratory conditions
bacterial growth
generally follows a
characteristic pattern
4 phases
normal growth
curve, with optimum
environmental and
nutritional conditions
6. Bacterial Growth Curve:
laboratory conditions
lag phase
no increase in cell
numbers
cells are adapting to
the environment
cells are preparing
for reproduction
synthesizing new
DNA, etc.
7. Bacterial Growth Curve:
laboratory conditions
log phase
exponential phase
maximal rate for
reproduction
this happens with a
specific set of growth
conditions
those resources for
growth are
abundantly
available
8. Bacterial Growth Curve:
laboratory conditions
stationary growth phase
maximum population
for the resources
available
required nutrients
become depleted
inhibitory end
products from cell
metabolism
accumulate
cell growth = cell
death
11. Continuous culture studies were carried out at three
temperatures (65, 70, and 75°C) with a culture volume of
350 ml, provided with agitation (200 rpm). Temperature
was accurately regulated with rheostat-controlled heat
tapes and a thermostatically controlled heating element.
Aeration was provided by controlling the flow rate (350
cm3/min) of air enriched with 5% (vol/vol) C02, using a
Manostat flow meter .The culture pH remained constant
(6.7 ± 0.2) during steady states. Wall growth was
minimized by coating the culture vessel with 5% (vol/vol)
dichlorosilane.
12. Determination of μ-max by
washout kinetics
The maximum specific growth rate (μ-max) was
determined by washout kinetics .
During washout, cells were counted at 0.5-h intervals
over 4 h, using a Petroff- Hauser bacterial counter.
Cell numbers were also determined by absorbance
at 460 nm, using a cell number-absorbance
calibration curve.
13. The equations of Marr et al. and Pirt were used to
account for substrate used for growth and
maintenance, where maintenance is the
consumption of potential biomass-
μX/Y=μX/YG +aX/YG -(1)
Where, μ = specific growth rate, X = biomass, Y =
actual or observed yield, YG = theoretical growth
yield (yield corrected for maintenance), a = specific
maintenance rate, and m = maintenance
coefficient = a/YG.
Determination of growth efficiency (Eg)
14. When μ = μmax, the equation becomes:
μ –maxX/Y = μ–maxX/YG + aX/Y; -(2)
Thus, the total rate of substrate utilization at μ max (μ maxX/YT)
equals the rate used for growth (μ-maxX/YG) plus that used for
maintenance (aX/YG). The fraction
(F) of substrate used for growth at μ -max is:
F = (μ –max X/YG)(μ-maxX/Y) -(3)
Substituting for μ-maxX/Y from equation (2) results in the
following ratio:
F = (μ –max X/YG)/[μ–maxX/YG + aX/Y] -(4)
By cancelling terms and defining F as the growth
efficiency, the following equation is obtained:
Eg = μ-max/(μ-max + a).
Growth efficiency (Eg) can then be determined from
μ -max and the specific maintenance rate (a).
15. RESULTS AND DISCUSSION
The Eg for T. thiopara at 70°C indicates that
84% of the theoretical growth yield was attained
(Table 1). Literature values were used to obtain
a, Ymax, YG, and Eg for other organisms grown
under a variety of conditions (Table 2). The
growth efficiency of T. thiopara at μ -max (0.84
h-1) was lower than those of Thiobacillus ferroxidans
(0.94 h-1) and Thiobacillus dentrificans
(0.94 h-1) but greater than that of Thiobacillus
neapolitanus (0.60 h-1 ). The lower growth
efficiency of T. thiopara was due to its higher
specific maintenance rate (a).