Screening of Antibiotic Gene Clusters in Microorganisms Isolated from Wood

The biosphere of Earth is made up of a variety of ecosystems governed by complex biological interactions, some of them mediated by microbial bioactive secondary metabolites. These metabolites such as antibiotics (e.g., polyketides and nonribosomal peptides) have been receiving increasing attention, due to their multiple pharmaceutical uses. Besides, antibiotic resistance is on the rise, and it is currently regarded as one of the greatest threats to global human health. The screening of novel antimicrobial polyketides and nonribosomal peptides in poorly studied ecosystems is an interesting alternative to address the problem of antibiotic resistance. This chapter updates a molecular method to identify antibiotics gene clusters and their subsequent production and activity validation. On the one hand, a PCR method based on degenerated primers for nonribosomal peptide synthases (NRPS) and the polyketide synthases (PKS) genes is used as an initial fast screening. On the other hand, a bioassay-based method is the protocol selected for the production confirmation and antibacterial effect estimation. These methods are applied to screen Actinobacteria and Penicillium species as main antibiotic producers isolated from wood.