text: Understanding the mechanisms and purposes of lactonase activity could lead to potential applied roles for these lactonases to control bacterial infections by inhibiting quorum-sensing activity and bring about profound effects on human health and the environment. However, in both the chemical and enzymatic lactonolysis, the reaction is reversible, complicating direct therapeutic application of lactonases.
  Pseudomonas aeruginosa, is an AHL-producing bacteria an opportunistic pathogen that infects immuno-compromised patients, and is found in lung infections of cystic fibrosis patients. P. aeruginosa relies on quorum sensing via production of lactones N-butanoyl--homoserine (C4-HSL) and N-(3-oxododecanoyl)-l-HSL (3-oxo-C12-HSL) to regulate swarming, toxin and protease production, and proper biofilm formation. The absence of one or more components of the quorum-sensing system results in a significant reduction in virulence of the pathogen.
  Erwinia carotovora is a plant pathogen that causes soft rot in a number of crops such as potatoes and carrots  by using  N-hexanoyl-l-HSL (C6-HSL) quorum sensing  to evade the plant's defense systems and coordinate its production of pectate lyase during the infection process.
  Plants expressing AHL-Lactonase were shown to demonstrate enhanced resistance to infection from the pathogen Erwinia carotovora. Expression of virulence genes in E. Carotovora is regulated by N-(3-oxohexanoyl)--homoserine lactone (OHHL). Presumably, OHHL-hydrolysis via lactonase reduced OHHL levels, inhibiting the quorum-sensing systems driving virulence gene expression.