Question

3. Discuss the phases of growth of bacteria by batch culture

Answer 1

The growth of bacteria in batch culture can be modeled with four & frent phases las phase (A).logphase or exponential phase B) stationary phase and death phase (D) 1. During lagphase, bacteria adapt to see toon contos It is the period bere the individual bacteria are stared at able to hide Danie the phase of the bacterial growth cycle, synthesis of RNA s and other molecules occurs During the ar phase celische very beau cols do norimedzev reproduce in a new medium. This pedodofde to no callaves is called the lag phase and can last for 1 hour to several days. During this phase cells are not do The log phase (sometimes called telesarithmic phase or the exponen passa period characterized by cel double The number of bacteria a p rin perunt time is proportional to depreet populian If not limited doubling will contineat a constatrate so both number of cells and the rate ofpation in doubles with each consecutive time period for this type of exponential growth plotting the natural logarithm of cell member a t produces a straight line Theslope of this line is the specific growth rate ofthe organism, which is a measure of the member of divisions per celpe mit time. The actual ree of this growth ie the slopeof the line in the figure) depends upon the growth conditions, which affect the frequency of all division events and the probability of both daughter cells surviving Under controlled conditions, cyanobacteria can double their population four times a day and then they aan triple their population Exponential growth cannot contime indefmitely, however, because temediumissoon depleted of mutients and enriched with wastes 3. The stationary phase is oftan due to a growth-limiting factor such as the depletion of an essential nutrient and or the fomation of an inhibitory product such as an organic acid Stationary phaseresults from a situation in which growth rate and death sate are equal The number of new cells created is limited by the growth factor and as a result these of cell growth matches the rate of cell death The reult is a smooth "horizontal linex pat of the curve during the stationary phase. Mitations can occur during stationary phase 4. At death phase decline phase). bacteria die This could be caused by lack ofruits, environmental temperature above or below the toleranceband for the species, or other injurious conditions 4 phases lag, exponential ationary and death Phases of Microbial Growth (Batch Culture)