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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). [3]
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 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.
[1] [2] They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. [3] [4] Antibiotics are not effective against viruses such as the ones which cause the common cold or influenza. [5] Drugs which inhibit growth of viruses are termed antiviral drugs or antivirals.
The Miles and Misra Method (or surface viable count) is a technique used in Microbiology to determine the number of colony forming units in a bacterial suspension or homogenate. The technique was first described in 1938 by Miles, Misra and Irwin who at the time were working at the LSHTM . [ 1 ]
The sample with the initial unknown bacterial concentration (C 0) is placed at a temperature favoring bacterial growth (in the range 37 to 42 °C if mesophilic microbial population is the target) and the electrical parameters R s and C s are measured at regular time intervals of few minutes by means of a couple of electrodes in direct contact ...
Bacteria are marked as sensitive, resistant, or having intermediate resistance to an antibiotic based on the minimum inhibitory concentration (MIC), which is the lowest concentration of the antibiotic that stops the growth of bacteria. The MIC is compared to standard threshold values (called "breakpoints") for a given bacterium and antibiotic. [28]
Antibiotics to which a bacterial isolate is partially susceptible will produce an intermediate size zone of inhibition (disk B). [1] [2] In drug discovery laboratories, the disk diffusion test is used to screen natural product extracts for antibacterial activity. Extracts with antibacterial activity, for example the petroleum ether, chloroform ...