GROWTH CURVES -
S-shaped or sigmoid -
Described by Verhuhst in 1839.
It shows 5 phases -
(i) Lag phase
(ii) Positive acceleration phase
(iii) Exponential phase
(iv) Negetive accesleration phase
1. Lag phase -
2. Positive acceleration phase -
3. Exponential phase -
4. Negetive accesleration phase -
5. Stationary -
If semi log curve is drawn for bacteria curve is in the form of straight line.