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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 cell wall of both gram-positive and gram-negative bacteria is a tight covalently bound and cross-linked peptidoglycan network and essential for bacterial growth, cell division and cellular structure. Therefore, bacteria need enzymes that can cleave the cell wall during bacterial growth and cell division. The cell wall of bacteria is built ...
μ is the growth rate of a considered microorganism, μ max is the maximum growth rate of this microorganism, [S] is the concentration of the limiting substrate S for growth, K s is the "half-velocity constant"—the value of [S] when μ/μ max = 0.5. μ max and K s are empirical (experimental) coefficients to the Monod equation. They will ...
In the absence of antibiotics or other stressors, filamentation occurs at a low frequency in bacterial populations (4–8% short filaments and 0–5% long filaments in 1- to 8-hour cultures). [3] The increased cell length can protect bacteria from protozoan predation and neutrophil phagocytosis by making ingestion of cells more difficult.
β-Lactam antibiotics are indicated for the prevention and treatment of bacterial infections caused by susceptible organisms. At first, β-lactam antibiotics were mainly active only against gram-positive bacteria, yet the recent development of broad-spectrum β-lactam antibiotics active against various gram-negative organisms has increased their usefulness.
Examples of such elements include plasmids, transposable genetic elements, and genomic islands, which can be transferred between bacteria through horizontal gene transfer. [41] A defining characteristic of MRSA is its ability to thrive in the presence of penicillin -like antibiotics, which normally prevent bacterial growth by inhibiting ...
While the MIC is the lowest concentration of an antibacterial or antifungal agent necessary to inhibit visible growth, the minimum bactericidal concentration (MBC) is the minimum concentration of an antibacterial agent that results in bacterial death. It is defined by the inability to re-culture bacteria, and the closer the MIC is to the MBC ...