The drugs which are active against microbial growth are of two types: those produced by micro-organisms, classed as antibiotics,and those which are synthetic. The antibiotics form the largest group and these may be defined as substances which, produced by micro-organisms, inhibit the growth of or kill other microorganisms. Even this is not a completely satisfactory definition since some microorganisms produce enzymes which are secreted extracellularly which can kill other cells, and other organisms produce protein factors which also can kill cells, for example the colicins, the killer factors of yeast and the kappa particles of Paramecium. Most antibiotics are secondary metabolites. These are substances which are produced at the end of the growth phase of micro-organisms in situations when the cells have stopped dividing (see figure 2.1).
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2.7 References and Further Reading
- Hewitt, W. (1977). Microbiological Assay-An Introduction to Quantitative Principles and Evaluation. Academic Press, LondonGoogle Scholar
- Kavanagh, F. (1963/72). Analytical Microbiology. Academic Press, London, Vol.1 (1963), Vol.2 (1972)Google Scholar
- Meselson, M. and Russell, K. (1977). In Origins of Human Cancer. (H. H. Hiatt, J. D. Watson and J. A. Winston eds), Cold Spring Harbor Publications, New York, pp. 1473–82Google Scholar
© David Edwards 1980