Soil is one of the principal ingredients of the universe, which supports all
forms of life directly or indirectly. Soil consists of a mixture of various organic and
inorganic matter, fluids, gases, and micro and macro-living systems and acts as a major
living medium for a wide group of living organisms. One of the important soil
inhabitants are microorganisms. Soil microorganisms can be categorized as bacteria,
fungi, actinomycetes, protozoa, algae, and viruses. These microbes have varied features
and functions. Most importantly, these microorganisms do not exist in isolation but
interact with each other and contribute significantly to overall soil fertility. Many of
these organisms have the capacity to produce antimicrobial substances as a defense
mechanism to compete with other organisms for their survival and existence. Most of
these antimicrobial substances, which are released as metabolites produced during
trophophase as well as in idiophase, are medically significant in the treatment of many
life-threatening infections in plants and animals. This chapter describes various soil
microflora and their roles in the production of different kinds of antimicrobials. The
primary goal is to familiarise readers with the various microflora found in soil and their
ability to produce anti-microbial components.
Keywords: Actinomycetes, Antibiotics, Bacteria, Fungi, Isolation, Soil micro-flora.
