Protein Domain Fold Similarity and Natural Product Structure as Guiding Principles for Compound Library Design -- Sources of Polyketides and Non-Ribosomal Peptides -- Polyketide Synthases: Mechanisms and Models -- Functional and Structural Basis for Targeted Modification of Non-Ribosomal Peptlde Synthetases -- Prerequisites for Combinatorial Biosynthesis: Evolution of Hybrid NRPS/PKS Gene Clusters -- Engineering Glycosylation in Bioactive Compounds by Combinatorial Biosynthesis -- Glycosyltransferases and Other Tailoring Enzymes as Tools for the Generation of Novel Compounds -- Enzymatic Incorporation of Halogen Atoms into Natural Compounds -- From Glucose to Antibiotics: What Controls the Fluxes? -- Precursor-Directed Biosynthesis for the Generation of Novel Glycopetides -- Tool-Box: Tailoring Enzymes for Bio-Combinatorial Lead Development and as Markers for Genome-Based Natural Product Lead Discovery -- Natural Product Biosynthetic Assembly Lines: Prospects and Challenges for Reprogramming.