Final answer:
To determine bacterial growth rate, both direct methods like counting colony-forming units and indirect methods like measuring turbidity or metabolic activity are used, especially during the log growth phase where growth is exponential.
Step-by-step explanation:
Measurement of Bacterial Growth Rate
To determine bacterial growth rate, both direct methods like counting colony-forming units and indirect methods like measuring turbidity or metabolic activity are used, especially during the log growth phase where growth is exponential.
The common approach for determining the bacterial growth rate involves observing the cells during the logarithmic (log) growth phase, where bacteria divide by binary fission and their numbers increase exponentially. This exponential growth can be represented on a semilogarithmic graph making the growth rate appear linear. To measure the growth, both direct and indirect methods are used. Direct methods include techniques such as viable cell counts using pour plate or spread plate methods and membrane filtration. Indirect methods estimate cell density by measuring turbidity with a spectrophotometer or by assessing metabolic activity which reflects live cell density.