Required for rhamnolipid surfactant production (PubMed:15126453). Supplies the acyl moieties for rhamnolipid biosynthesis by competing with the enzymes of the type II fatty acid synthase (FASII) cycle for the beta-hydroxyacyl-acyl carrier protein (ACP) pathway intermediates. Catalyzes the formation of one molecule of beta-hydroxydecanoyl-beta-hydroxydecanoate from two molecules of beta-hydroxydecanoyl-ACP. Is the only enzyme required to generate the lipid component of rhamnolipid. In vitro results establish that RhlA is highly selective for 10-carbon acyl-ACP intermediates and thus functions as the molecular ruler that controls the acyl chain composition of rhamnolipids. Cannot use beta-hydroxydecanoyl-CoA as substrate (PubMed:18326581). Rhamnolipid production plays an important role in swarming motility (PubMed:15126453). 2 (3R)-hydroxydecanoyl-[ACP] + H2O = (3R)-3-[(3R)-3-hydroxydecanoyloxy]decanoate + H(+) + 2 holo-[ACP] Lipid metabolism; rhamnolipid biosynthesis. Monomer. By nitrogen starvation (PubMed:8051059). Expression is about 20-fold higher in stationary phase (PubMed:8051059). Positively regulated by the translational regulator CsrA (RsmA) (PubMed:15126453). Loss of rhamnolipid production and of swarming mobility (PubMed:15126453). Belongs to the AB hydrolase superfamily.