Physical and chemical control of growth and viability

Physical and chemical control of growth and viability
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Physical and chemical control of growth and viability
Phases of the bacterial growth curve
Bacterial growth entails four different phases.
1 The lag phase: at this stage, the bacteria adapt to the conditions of growth. This is when the bacteria mature; however, they are not able to divide at this stage. In the lag phase, the synthesis of enzymes, RNA, and other molecules takes place (Kimura, 2008)
2 The log phase: this phase is also referred to as the exponential phase, logarithmic phase. It is characterized by doubling of cells. Doubling of cells continues at a constant rate when the growth is unlimited. Therefore, both the rate of the population increase and the number of cells doubles with every period of a consecutive time. A straight line is produced when natural cell number logarithms are plotted against time. The slope is the specific rate of growth, a measure of per cell division per unit time. Conditions of growth determine the actual growth rate, and affect the cell division frequency and the survival probability of the daughter cells. However, the exponential growth is unable to indefinitely continue because the medium is enriched with wastes and depleted of nutrients in a short while (Anderson, 2012).
3 The stationary phase: this phase results from the limiting factors of growth like the formation of the inhibitory product, organic acid and the depletion of an essential nutrient. Stationary phase is brought about by the equivocal rate of growth and rate of death. The growth factor limits the creation of new cells; hence the growth rate of cells matches the death rate of cells. This results in a smooth horizontal line curve.
4 The death phase: also referred to as the decline phase. At this phase, the bacteria die due to lack of nutrients.
Two methods used to measure microbial growth
There are various meth...