ABSTRACT
Secondary metabolites from microorganisms and plants are typically low-molecular-weight natural products that are generally not essential for survival and growth of the producing organisms but are involved in the interactions of microorganisms and plants with their environment as a result of secondary metabolism regulation. The major microbial system used for secondary metabolites production and strain improvement is the bacterium Escherichia coli, which was the first species to be used to produce a commercial therapeutic protein. The type of fermentation used, as well as its size, duration, and nutrient profile, will depend critically on the nature of the microbial product. Medium-value products, such as antibiotics, are produced by microbes, which, when first isolated from the soil, usually make detectable, but vanishingly small, quantities of the bioactive substance. Specific enzymes digest the vegetative mycelium, in part, and the cellular building blocks that are released are used to construct the aerial mycelium.
