Non-ribosomal peptide biosynthesis is an enzyme-directed pathway by which microorganisms, particularly bacteria and fungi, assemble peptide natural products independently of ribosomal translation, messenger RNA templates, and transfer RNA-mediated decoding. It is principally mediated by non-ribosomal peptide synthetases (NRPSs): large, modular, multidomain enzymes in which successive modules determine the ordered incorporation of amino acid or other carboxylate-derived building blocks into a growing product ^[1][2]. A canonical elongation module contains an adenylation domain that selects and activates a substrate, a thiolation/peptidyl-carrier-protein domain that covalently tethers the activated intermediate through a 4′-phosphopantetheinyl arm, and a condensation domain that forms the peptide bond with the upstream intermediate ^[1][3]. Optional catalytic domains can alter tethered residues, including by epimerization or heterocyclization, while terminal release domains commonly liberate the product through hydrolysis, cyclization, or related reactions ^[2][3]. The pathway is distinguished from ribosomal peptide biosynthesis by its assembly-line enzymology and its capacity to incorporate diverse non-proteinogenic substrates rather than being limited by the genetically encoded translation system ^[1][2].