The search for new antibiotics or new antibiotic producing microbial strains continues to be of utmost importance in research programs around the world because of the increase of resistant pathogens and toxicity of some used chemical antibiotics. Among actinomycetes a large number of antibiotics were obtained from the genus Streptomyces (Alan and James, 2007; Lyudmila et al., 2008; Junker et al., 2009; Koch and Loffler, 2009). Streptomyces are widely recognizedas industrially important microorganisms because of their ability to produce many kinds of novel secondary metabolites including antibiotics (Williams et al., 1983). Indeed, different Streptomyces species produce about 75% of commercially and medically useful antibiotics (Miyadoh, 1993).
Streptomyces species are distributed widely in marine and terrestrial habitats (Pathomareeet al., 2006) and are of commercial interest due to their unique capacity to produce novel metabolites. In fact, the genus Streptomyces alone accounts for a remarkable 80% of the actinomycete natural products reported to date, a biosynthetic capacity that remains without rival in the microbial world (Watveet al., 2001). It was also expected that Streptomyces species will have a cosmopolitan distribution, as they produce abundant spores that are readily dispersed (Antony-Babuet al., 2008). These filamentous bacteria are well adapted to the marine environment and are able to break down complex biological polymers. Marine Streptomyces are widely distributed in biological sources such as fishes, molluscs, sponges, seaweeds, mangroves, besides seawater and sediments. The genus Streptomyces was classified under the family Streptomycetaceae, which includes Gram-positive aerobic members of the order Actinomycetales and suborder Streptomycineae within the new class Actinomycetes (Stackebrandtet al., 1997; Anderson and Wellington, 2001). They have DNA G ± C content of 69–78 mol%. These organisms are gaining importance not only for their taxonomic and ecological perspectives, but also for their production of novel bioactive compounds like antibiotics, enzymes, enzyme inhibitors, pigments and for their biotechnological application such as probiotics and single cell protein.
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