Selected recent examples of NP discovery employing the metagenomic approach. (A) The hys and red gene clusters containing Trp dimerization enzyme sequence tag (depicted in green), which were expressed in S. albus and E. coli, respectively, afforded two new rare tryptophan dimers, hydroxysporine and reductasporine. (B) The malacidin BGC containing the Asp4 (the domain responsible for incorporating the first aspartic acid) gene sequence that was expressed in S. albus led to the production of malacidins A and B containing a rare 3-hydroxyl aspartic acid moiety (HyAsp, highlighted in purple). (C) The metagenome sequencing of the DNA sample of whole-tunicate D. molle E11-036 revealed the BGC of divamide A (the core peptide divamide A is shown in black).