9 June 2008 Issue 10
Conventional Scanning Electron Microscopy of Bacteria
Scanning electron microscopy (SEM) is one of the best suited out of a variety of procedures to visualise the external appearance of bacteria. Bacteria live in various environments and their preparation for SEM thus takes their nature into consideration. The basic principles of isolation, fixation, dehydration, drying, mounting, and photographing have many variations, some of which are discussed in this article.
Bacteria are present everywhere: in the soil, deep in the rocks, in all bodies of water, in the atmosphere, including the clouds, and also on and inside other living organisms. Their effects on higher life forms are known for only a limited number of bacterial species. Some are harmful - pathogenic - causing diseases in plants or in animals including humans, and some are useful to humans either as “probiotic” bacteria protecting health (Karpa, 2006), or industrially by participating in the production of various commodities. The effects of most bacteria are not known. A new trend is in progress (Sachs, 2008) not to exterminate harmful bacteria in human and animal environments but to replace them with beneficial ones. Bacteria which are genetically programmed to die after their mission has been accomplished in humans or animals are part of the new trend. These minute microorganisms have farreaching macroscopic consequences. They are of interest to agriculture because they may harm or
improve the production of foods, either animal or plant, and thus affect human civilisation.
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