Figure 2. Metagenome-driven drug discovery with an alternative targeted sequence-based pipeline.

(a) Environmental DNA (eDNA) is extracted, cloned and ligated into a shuttle vector, and then transformed into a host cell to create a metagenomic library. Conventional function- and sequence-based methods involve screening metagenomic libraries for easily observable phenotypes or the presence of target DNA sequences, respectively. Target biosynthetic pathways are identified, assembled and functionally expressed through a variety of methods to obtain the encoded natural product for characterization. (b) Alternatively, PCR is used to profile the biosynthetic pathways present in crude eDNA samples. The PCR amplicons are phylogenetically organized to predict the chemical output of the biosynthetic pathways. Samples predicted to harbor novel or target biosynthetic gene clusters are prioritized for library construction, clone recovery, and heterologous production. Reproduced and adapted from [84] with permissions from Springer.