Esterase whose enzymatic activity is required for rhamnolipid production, all kinds of cell motility (swimming, swarming, and twitching), and biofilm formation; the exact role of EstA in these processes is unclear. In vitro, has pronounced esterase activities towards p-nitrophenyl esters of short acyl chain length (C4-C6) and Tween detergents. Also shows relatively high activity towards beta-naphthyl butyrate, whereas its activities towards triacylglycerols and acyls-CoA are negligible. a carboxylic ester + H2O = a carboxylate + an alcohol + H(+) Contains a C-terminal autotransporter domain that integrates into the outer membrane and enables the translocation of the catalytic N-terminal domain to the bacterial cell surface. Strains lacking this gene produce only marginal amounts of extracellular rhamnolipids. They also show no swarming motility, and both other forms of surface motility, swimming and twitching, are completely absent in these mutant cells. Biofilm formation is also affected. Overexpression of EstA results in an increased production of rhamnolipids (PubMed:17631636). Rhamnolipid production is strongly influenced by the C/N ratio of the environment. At a C/N ratio of 83.2, a modified P.aeruginosa strain capable of overexpressing the estA gene can produce up to 3.9 times more rhamnolipids than the wild-type strain (PubMed:28837648). Belongs to the 'GDSL' lipolytic enzyme family.