Natural products obtained from the microbes have been reported as substitutes to contemporary drugs obtained from plants. With the increasing need for new therapies, new natural products are being explored using the traditional methods. As only a small fraction of microbes can be cultured in the laboratory, many microbes continue to remain unexplored for their ability to synthesize secondary metabolites. In the past few decades, the reduced cost of DNA sequencing and developments in computational tools have made the Metagenomic Approach effective and popular. Uncultured microbes can be studied through bioprospecting of the unexplored geographical niches. Moreover, Bioinformatics tools have enabled us to find the gene clusters that, in metagenomics, imply the real potential of finding novel open reading frames (ORFs). Screening of genomes for secondary metabolite-genes like nonribosomal peptide synthases (NRPS) and polyketide synthases (PKS), has resulted in the discovery of new or previously known metabolites. Technological advancement and innovations in the culture-independent approach have allowed us to explore novel chemistries from environmental samples to identify the molecules of therapeutic value. This chapter will discuss the methods for identifying secondary metabolite genes from the genome, and the new approaches for functional metagenomic screening toward the discovery of antimicrobials. Moreover, insights into this approach will be provided to generate opportunities to explore natural products for combating the global demand for novel antibiotics.
Keywords: Antimicrobial, Bioinformatics, Bioprospecting, Metagenomics, Mining, Multi-Drug Resistance, Non-Ribosomal Peptide Synthases, Polyketide Synthases, Secondary Metabolite-Regulated Expression, Substrate-Induced Gene Expression.