Phylogeny of bacterial ketoacyl synthase domains and their distribution in cyanobacterial PKS PUFA gene clusters. A. Maximum likelihood phylogenetic tree of bacterial KS based on 235 conserved amino acids from 217 gene clusters encoding secondary lipids biosynthesis and enediynes. The clades of the phylogenetic tree supported by a bootstrap of ≥70% are indicated by a black dot. B. PKS gene clusters dedicated to PUFA and enediynes in Cyanobacteria. The background color of each KS refers to the corresponding clade of the adjacent phylogenetic tree. PKS genes are indicated in blue, whereas homologous genes are indicated by similar colors. KS, ketoacyl synthase; AT, acyltransferase; KR, ketoacyl reductase; ACP, acyl carrier protein; DH, dehydratase; ER, enoyl reductase; TER, thioester reductase.