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Chapter 13 : Extraordinary Ecology: an Amazing Diversity of Life Styles
Ecology is the branch of biology that deals with the relationships of organisms to one another and to their surroundings. In comparison with other kinds of living creatures, microbes are extraordinary with respect to the great diversity of ecological niches in which different species can grow. In other words, in the microbial world a particularly wide range of chemical and physical conditions can be tolerated and exploited. Some microbes, however, have the capacity to grow in solutions that contain very high concentrations of salts or other small molecules. These are known as osmophiles or halophiles (halos is Greek for “salt”). Certain microbial species called acidophiles are well adapted to life in acidic environments. Magnetotactic bacteria behave as bar magnets because each cell contains either one or two chains of magnetite particles. Further studies on magnetotactic bacteria may help to explain the purpose of magnetite throughout the animal kingdom. Looking for microbes in deep subsurface locales is usually approached by examining cores obtained by drilling from the surface. Recent reports indicate the presence of microbes in the pores of rocks that are deep below the Earth's surface (as far as 400 meters below ground). The symbiotic N2 fixation system of legumes is one example of microbes living in close association with higher organisms. Chemical "communication" between different species of microbes is an inherent feature of the carbon, nitrogen, and sulfur cycles. Life in a consortium is very economical and also greatly reduces dependence on environmental supplies of crucial nutrients.