2.2 Rare Actinomycetes: Future Gold Mine of Bioactive Compounds......................

Abstract Microbes continue to play a highly considerable role in the drug dis-covery and development process. Nevertheless, the number of new chemical entities (NCEs) of microbial origin that has been approved by the Food and Drug Administration (FDA) has been reduced in the past decade. This scarcity can be partly attributed to the redundancy in the discovered molecules from microbial isolates, which are isolated from common terrestrial ecological units. However, this situation can be partly overcome by exploring rarely exploited ecological niches as the source of microbes, which reduces the chances of isolating com-pounds similar to existing ones. The use of modern and advanced isolation tech-niques, modification of the existing fermentation methods, genetic modifications to induce expression of silent genes, analytical tools for the detection and identifi-cation of new chemical entities, use of polymers in fermentation to enhance yield of fermented compounds, and so on, have all aided in enhancing the frequency of acquiring novel compounds. These compounds are representative of numerous classes of diverse compounds. Thus, compounds of microbial origin and thei