Microbes are useful to humans in innumerable ways. Members of this group of organisms are involved in human pursuits that range from producing and testing medicine to growing, preparing and digesting food. The scientific study of microbes enriches humanity's understanding of genetics, disease and other aspects of life on planet Earth.
Microbes aid humans directly in many ways. Some microbes produce medicinal or bio-active compounds, such as the antibiotic penicillin, which is naturally derived from a type of mold. Other microbes are used to ferment vegetables, grains and milk products to make pickles, bread, alcohol, yogurt and cheese. Scientists use microbes as model organisms and living tools in the laboratory, and using microbes to study human genetics, biochemistry and disease has revolutionized human understanding of the biological world. Microbes are also used to perform essential steps in industrial processes such as the reclamation of waste water.
Natural microbial activity also confers indirect advantages to humanity. The decomposition of organic matter and the recycling of nutrients in agricultural and natural ecosystems is accomplished by microbes. Microbes are also responsible for the fixation of atmospheric nitrogen, which enhances soil fertility in these systems. Naturally occurring microbial communities also help control the spread of plant and animal pathogens and limit the population size of insect pest populations. Ultimately, microbes are responsible for regulating most of the global systems that make Earth hospitable to human habitation.