text: Lactonases are able to interfere with AHL-mediated quorum sensing. Some examples of these lactonases are AiiA produced by Bacillus species, AttM and AiiB produced by Agrobacterium tumefaciens, and QIcA produced by Hyphomicrobiales species.
  Lactonases have been reported for Bacillus, Agrobacterium,  Rhodococcus, Streptomyces, Arthrobacter, Pseudomonas, and Klebsiella. The Bacillus cereus group (consisting of B. cereus, B. thuringiensis, B. mycoides, and B. anthracis) was found to contain nine genes homologous to the AiiA gene that encode AHL-inactivating enzymes, with the catalytic zinc-binding motif conserved in all cases.
  In the phytopathogen A. tumefaciens, AiiB lactonase acts as a fine modulator that essentially delays the release of lactone OC8-HSL and the resultant number of tumors produced by the pathogen. AttM lactonase mediates the degradation of the lactone OC8-HSL in wounded plant tissues.
  The primary activity of the anti-atherosclerotic paraoxonase (PON) enzymes is as lactonase.  Oxidized polyunsaturated fatty acids (notably in oxidized low-density lipoprotein) form lactone-like structures that are PON substrates.