MICROBIAL GROWTH 4
Microbialgrowthis the reproduction of bacteria through a process of binary fission.According to Koch(2001),bacteria growth involves the asexual reproduction of a bacteriumthrough cell division where one bacterium divides into two. Theprocess of microbial growth leads to the formation of anotheridentical bacterium in terms of genetic makeup. The whole concept ofmicrobial growth is described by a consistent growth of the bacteriathrough the repeated series of cell division (Jay, 2000). This ispossible through the repetition of the division process in what iscommonly called the “local doubling” process that creates a largepopulation of the bacteria in a certain period of time.
TheMicrobialgrowth series of local doubling occurs because the cells produced bythe initial cell division process also undergo the same process. Thedaughter cells divide to form other cells that also continue with theprocess (Koch,2001).As a result, bacterial growth involves an exponential growth, whichhappens in four main phases. The first phase of microbial growth isthe lag phase. According to Jay (2000), this is the phase where thebacteria adapt themselves to the surrounding environment. This way,they adapt to the growth conditions in the environment so that theircells can acclimatize to the environment. In addition, the enzymesand molecules needed for the cell division process are also preparedby the cell.
Thelog phase is the next stage of microbial growth when the celldoubling occurs. This period is characterized by a consistent seriesof cell division that produces a number of bacteria that isproportionate to the population (Koch,2001).The constant rate of division marks the rate of increase, but thepopulation grows exponentially because the new cells also divide toform new ones. However, the actual rate of the exponential growth ofthe bacteria depends on the conditions of growth that the bacteriaare exposed to (FDA, 2015). Favorable growth conditions lead to ahigh growth rate while unfavorable conditions reduce the rate.However, the exponential growth cannot go on for an indefinite time,it changes leading to the third phase.
Thethird phase is the stationary phase, marked by a slow growth ratethat equals the death rate. At this phase, the number of the newbacteria and the dying bacteria equals. The rate of multiplication ordoubling reduces because of biological and environmental reasons.According toKoch (2001), therate of growth slows down due to the depletion of the nutrients bythe increasing population of bacteria. Therefore, the number of newcells is consistently limited as more of them die. Therefore, thefinal phase of the exponential growth starts. The death phase or thedecline phase is marked by the death of the bacterial population.According to Jay (2000), the death phase is a as a result ofincreased temperatures, poor living conditions and depletion ofnutrients.
Bacteriagrowth is aided by several factors that favor the internal andexternal environment of the bacteria. One of the factors is themoisture content of the environment (FDA, 2015). This is becausemicrobial growth requires water as the microorganisms requiremoisture to grow. Other factors are the pH levels of the environmentand nutrient content. High acidity limits the growth of microbialgrowth while the nutrients feed the cell (FDA, 2015). Therefore,limiting the favorable factors will limit the rate of microbialgrowth and reduce the population of the microbes.
FDA,2015. Evaluationand Definition of Potentially Hazardous Foods – Chapter 3. Factorsthat Influence .Retrieved From,<http://www.fda.gov/Food/FoodScienceResearch/SafePracticesforFoodProcesses/ucm094145.htm>April 14, 2015
Jay,J.M. (2000). Modernfood microbiology. 6th ed.Gaithersburg: Aspen Publishing
Koch,A. (2001). BacterialGrowth and Form.Berlin: Springer Science & Business Media