Abstract
The secondary metabolites isolated from microbes and exhibits either antimicrobial (antibacterial, antifungal and antiprotozoans), antitumor and/or antiviral activities, used to be called as antibiotics. Secondary metabolites are also known as bioactive metabolites which work against microbes. There are more than 70% of the antibiotics can be obtained from members of the Actinomycetes family and it has been suggested that a large number of Actinomycetes may still be unknown with a potential to produce antibiotics. The presence of Multidrug resistant bacteria (MDR) is also responsible for the research of novel antibiotics and novel microbes. Exhibiting various bioactivities, they provide valuable approved drugs in clinical use. Actinobacteria, which share the characteristics of both bacteria and fungi, are widely distributed in both terrestrial and aquatic ecosystems, mainly in soil. They are considered as the biotechnologically valuable bacteria that are exploited for its secondary metabolite production. Approximately, 10,000 bioactive metabolites are produced by Actinobacteria, which is 45% of all bioactive microbial metabolites discovered. Especially Streptomyces species produce industrially important microorganisms as they are a rich source of several useful bioactive natural products like biosurfactant, enzyme, bioherbicides, vitamins, pigments, bioremediation, phytohormone production, odor and flavor compounds production etc. with potential applications. Though it has various applications, some Actinobacteria have its own negative effect against plants, animals, and humans. In this survey, a large number of the actinomycetes inhabit natural substrates which have the capacity to inhibit the growth of bacteria and other microorganisms. The ability of these actinomycetes to exert an inhibiting effect upon microorganisms is highly specific. Antagonistic actinornycetes produce a variety of antibiotics that vary in chemical nature, in antimicrobial action, in toxicity to animals, and in their chemotherapeutic potentialities. The antibiotics that have, so far, been isolated from actinomycetes vary in the degree of purification include: actinomycctin, actinomyces lysozyme, actinomycin, micromonosporin, streptothricin, streptomycin, and mycetin. Some actinomycetes produce more than one antibiotic substance. Some antibiotics are produced by several different organisms.