Molecular beacons to identify gifted microbes for genome mining

Microbial genome mining is a promising technology that is revitalizing natural product discovery. It is now well documented that many bacteria with large genomes, particularly actinomycetes, encode many more secondary metabolites (SMs) than was previously known from their expressed secondary metabolomes. There are effective bioinformatics tools for counting the numbers and nature of SMs, and determining the total coding capacity from finished microbial genomes. However, these methods do not translate well to draft genomes, particularly for large SM gene clusters that contain nonribosomal peptide synthetase (NRPS) or type I polyketide synthase (PKS-I) mega-genes which are prone to fragmentation and misassembly. Small molecular beacons are required to assess the numbers and variety of NRPS, PKS-I and mixed NRPS/PKS-I pathways. In this report, I show that concatenated peptidyl carrier protein-thioesterase di-domains and acyl carrier protein-thioesterase di-domains can be used as multi-probes to survey finished or draft genomes to estimate the numbers of NRPS, PKS-I and mixed NRPS/PKS-I gene clusters to identify gifted actinomycetes.