Saprophytes

Saprophytes - organisms that use as power sources substrates from inanimate objects, in contrast to bacteria, parasites, capable of living at the expense of the products of metabolism in the tissues of living organisms. Saprophytes widely distributed in nature, found in soil, water, air, humans and animals.
As a rule, saprophytes are not pathogenic microorganisms, however there are microbes, leading saprophyte way of life, but has nevertheless pathogenicity for humans (the causative agent of botulism). Saprophytes in large numbers are found in the human body, especially in cavities, communicating with the external environment. In violation of the mechanisms of natural immunity (see) some saprophytes (Escherichia coli, Proteus) can cause disease (sepsis, meningitis, and others).