Exponential or Logarithmic (log) phase
*During this phase, the microorganisms are in a rapidly growing and dividing state.
**Their metabolic activity increases and the organism begin the DNA replication by binary fission at a constant rate.
**The growth medium is exploited at the maximal rate, the culture reaches the maximum growth rate and the number of bacteria increases logarithmically (exponentially) and finally the single cell divide into two, which replicate into four, eight, sixteen, thirty two and so on (That is 20, 21, 22, 23.........2n, n is the number of generations)
**This will result in a balanced growth.
****The time taken by the bacteria to double in number during a specified time period is known as the generation time. The generation time tends to vary with different organisms. E.coli divides in every 20 minutes, hence its generation time is 20 minutes, and for Staphylococcus aureus it is 30 minutes.