Steady-State Growth & Continuous Growth :

Steady-State & Continuous Growth :

A culture is said to be in steady-state growth (Balance Growth) when all of its  components double at each division.

Chemostat : 

In chemostat continuous growth takes place.

A reservoir fresh medium continuous supply into growth chamber at a flow rate (f) set by the operator.In the chemostat the concentration of the limiting nutrient in the reservoir is very low so that growth is limited by availability of the nutrient.

When a drop of fresh medium enters the growth chamber the growth limiting nutrient is immediately used up and the cells cannot continue to grow until the next drop of media enters.This is because the growth rate is manipulated by adjusting the rate at which fresh medium enters the growth chamber.

          Concept Behind the Chemostat

D = F/V 

Where , 

F - Flow rate 

V - Volume of Medium in growth Chamber

D - Dilution rate 

Ex- Flow rate is 10 ml/h & Volume of medium is 1000 ml.

    D = F/V  

∴D = 10 ml/h⁻¹/1000

    D = 0.01 h⁻¹

Steady state growth : Realtionship of dilution rate (D) to growth rate constant (K) i.e. K=D When steady-state growth is reached in the growth chamber 

the rate of formation of new cells (Kx) = the rate of loss cells (Dx)

Kx = Dx (x will be cancelled from both sides)

Then ,

∴ K=D

Dependence of cell mass (x) on Concentration of nutrients in reservoir (Sr) -

The actual concentration of cells in the growth chamber is manipulated by changing the concentration of nutrients in the reservoir

Sr - Concentration of Nutrients in reservoir

S- Concentration of nutrients in growth chamber

The difference between Sr & S can be equal to the amount of nutrients used or uptake by the growing bacteria.

Y   = x/Sr-S

Yx = Sr-S

x   = Y (Sr-S) 

On rearranging equation , 

x =Y (Sr-S)