|Actinomycetes are a group of physiologically versatile, high GC, gram-positive, filamentous bacteria found in most environments including terrestrial and aquatic habitats. Streptomyces has been reported as the dominant genus in freshwater habitats whereas Micromonospora and related genera are predominant in freshwater and marine sediments.
There is increasing realization of the potential for wetlands as sources of actinomycetes that produce useful bioactive compounds. Cross reported freshwater habitats as promising sources of bioactive actinomycetes. Okami reported that actinomycetes of freshwater origin produce novel bioactive substances. There is an urgent need for screening of novel bioactive compounds from underexplored biotopes such as freshwater habitats. This is also dictated by the rise of emerging diseases and antibiotic-resistant human pathogenic bacteria such as multidrug resistant (MDR) strains of M. tuberculosis, vancomycin resistant enterococci (VRE), methicilin resistant Staphylococus aureus (MRSA), Pseudomonas aeruginosa and Candida albicans etc. The focus is increasing towards novel biotopes, niche ecosystems and extreme environments for isolating novel bioactive strains especially actinobacteria which produce nearly 80% of all known antibiotics. Additionally the microbial profiles also serve as an indicator of freshwater ecological health.
The microorganisms especially bacteria and actinomycetes are virtually unlimited sources of novel compounds with many therapeutic applications. Actinomycetes among them hold a prominent position due to diversity and proven ability to produce new structures. Actinomycetes are widely distributed in terrestrial and aquatic ecosystems. Especially in soil, actinomycetes play a crucial role in the recycling of refractory biomaterials by decomposing complex mixtures of polymers in dead plant, animal and fungal materials and capable of producing several secondary metabolites. But the rate of discovery of new compounds from terrestrial actinomycetes has decreased, whereas the rate of re-isolation of known compounds has increased. Thus, it is crucial that new groups of actinomycetes from pristine habitats need to be explored as sources of novel bioactive secondary metabolites.