, 1999; Li et al., 2005; Sujatha et al., 2005; Miller et al., 2007), and the vast majority of novel bioactive compounds are derived from the genus Streptomyces MK-8669 concentration (Bérdy, 2005; Dharmaraj, 2010). However, the discovery ratio of novel compounds from Streptomyces has decreased in recent years owing to the failure to dereplicate known compounds. Therefore, new and improved approaches for screening system are required to discover novel natural products. Actinomycete secondary metabolites

such as polyketides and nonribosomal peptides are often biosynthesized by large and multifunctional synthases that sequentially assemble small carboxylic acid and amino acid building blocks into their products in an assembly line, so genomics is particularly useful for microbial natural products studies (Fischbach & Walsh, 2006). Some unanticipated biosynthetic gene clusters have been revealed in the genome sequences of Streptomyces coelicolor and Streptomyces avermitilis, which suggested that the strains have the potential to yield new metabolites, and the genomic information has been used to predict the chemical structures of previously unobserved metabolites (Ōmura et al., 2001; Bentley et al., 2002; Udwary et al., 2011). Moreover, some significant and new natural products have been discovered based on genome scanning. (Zazopoulos et al., 2003;

McAlpine et al., 2005). Polyketides Buparlisib concentration are structurally diverse secondary metabolites with various biological activities (Monaghan & Tkacz, 1990; Komaki et al., 2009), which are biosynthesized

from acyl CoA precursors by polyketide synthases (PKSs) and three types of PKSs are known to date (Shen, 2003). Type II PKSs are multienzyme complexes that carry a core part (minimal PKS) consisting of two ketoacyl synthase (KSα and KSβ) subunits and one acyl carrier protein (ACP). KSα and KSβ catalyze the condensation of acyl-thioesters to form a carbon skeleton. KSβ also works as a chain length-determining factor, while ACP acts as an anchor for the growing polyketide chain during the condensation and subsequent modification steps (Shen et al., 2001; Staunton & Wilkinson, 2001). Until now, many molecular approaches Lck such as genome scanning have successfully revealed the presence of large numbers of cryptic or novel PKS genes that have the possibilities to produce novel polyketides (Metsä-Ketelä et al., 2002; Ikeda et al., 2003; Zazopoulos et al., 2003; Ayuso et al., 2005; McAlpine et al., 2005; Banskota et al., 2006; Ohnishi et al., 2008). For example, two novel angucyclines were discovered by way of the novel PKS genes analysis from a rubromycin producer (Metsä-Ketelä et al., 2004). With the development of sequencing technology, it is expediently to get the draft or complete genome sequences of streptomycetes that provide the abundant PKSs genes information to elucidate the probable metabolic pathways.