Biodiversity of Streptomyces from soil collected from various parts of Nepal and screening for potent bioactive compounds.
Funding Agency: University Grant Commission, Nepal
Project Introduction: Streptomyces is a genus of Gram-positive bacteria that grows in various environments, with a filamentous form similar to fungi (Procópio et al., 2012). Phylogenetically, Streptomyces are a part of Actinobacteria, a group of Gram-positives whose genetic material (DNA) is GC-rich (70%) when compared with other bacteria such as Escherichia coli (50%). They are ubiquitous soil-dwelling saprophytes known to produce secondary metabolites, many of which are antibiotics. The morphological differentiation of Streptomyces involves the formation of a layer of hyphae that can differentiate into a chain of spores. The most interesting property of Streptomyces is the ability to produce bioactive secondary metabolites such as antifungals, antivirals, antitumoral, anti-hypertensives, and mainly antibiotics and immunosuppressives (Omura et al., 2001; Khan, 2001; Patzer and Volkmar, 2010). Secondary metabolism is usually a late growth phase event, brought on by different signals, e.g., nutrient starvation, environmental signals.
Streptomyces is the largest antibiotic-producing genus in the microbial world discovered so far (Watve et al., 2001). They evolved about 450 million years ago as branched filamentous organisms adapted to the utilization of plant remains (Chater, 2006). The history of antibiotics derived from Streptomyces began with the discovery of streptothricin in 1942, and with the discovery of streptomycin two years later, scientists intensified the search for antibiotics within the genus. Today, 80% of the antibiotics are sourced from the genus Streptomyces, actinomycetes being the most important (Procópio et al., 2012).