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Bacterial growth curve\Kinetic Curve. In autecological studies, the growth of bacteria (or other microorganisms, as protozoa, microalgae or yeasts) in batch culture can be modeled with four different phases: lag phase (A), log phase or exponential phase (B), stationary phase (C), and death phase (D).
Figure 1: A bi-phasic bacterial growth curve.. A growth curve is an empirical model of the evolution of a quantity over time. Growth curves are widely used in biology for quantities such as population size or biomass (in population ecology and demography, for population growth analysis), individual body height or biomass (in physiology, for growth analysis of individuals).
The first phase is the fast growth phase, since the bacterium is consuming (in the case of the above example) exclusively glucose, and is capable of rapid growth. The second phase is a lag phase while the genes used in lactose metabolism are expressed and observable cell growth stops. This is followed by another growth phase which is slower ...
The Monod equation is a mathematical model for the growth of microorganisms. It is named for Jacques Monod (1910–1976, a French biochemist, Nobel Prize in Physiology or Medicine in 1965), who proposed using an equation of this form to relate microbial growth rates in an aqueous environment to the concentration of a limiting nutrient.
This open system allows researchers to maintain the exponential growth phase of cells for use in physiological experiments. [ 1 ] A chemostat (from chem ical environment is stat ic) is a bioreactor to which fresh medium is continuously added, while culture liquid containing left over nutrients, metabolic end products and microorganisms is ...
Cells in different growth stages have different physical properties. Cells in a culture can thus be physically separated based on their density or size, for instance. This can be achieved using centrifugation (for density) or filtration (for size). In the Helmstetter-Cummings technique, a bacterial culture is filtered through a membrane.
Schematic diagram of cellular growth (elongation) and binary fission of bacilli. Blue and red lines indicate old and newly generated bacterial cell wall, respectively. (1) growth at the centre of the bacterial body. e.g. Bacillus subtilis, E. coli, and others. (2) apical growth. e.g. Corynebacterium diphtheriae. This is bacterial proliferation.
The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. [124] [125] The second phase of growth is the logarithmic phase, also known as the ...