title: Synthesis of fruity ethyl esters by acyl coenzyme A: alcohol acyltransferase and reverse esterase activities in Oenococcus oeni and Lactobacillus plantarum.
abstract: OBJECTIVE
  To assess the abilities of commercial wine lactic acid bacteria (LAB) to synthesize potentially flavour active fatty acid ethyl esters and determine mechanisms involved in their production.
  
  
  RESULTS
  Oenococcus oeni AWRI B551 produced significant levels of ethyl hexanoate and ethyl octanoate following growth in an ethanolic test medium, and ester formation generally increased with increasing pH (4.5 > 3.5), anaerobiosis and precursor supplementation. Cell-free extracts of commercial O. oeni strains and Lactobacillus plantarum AWRI B740 were also tested for ester-synthesizing capabilities in a phosphate buffer via: (i) acyl coenzyme A: alcohol acyltransferase (AcoAAAT) activity and (ii) reverse esterase activity. For both ester-synthesizing activities, strain-dependent variation was observed, with AcoAAAT activity generally greater than reverse esterase. Reverse esterase in O. oeni AWRI B551 also esterified 1-propanol to produce propyl octanoate, and deuterated substrates ([(2)H(6)]ethanol and [(2)H(15)]octanoic acid) to produce the fully deuterated ester, [(2)H(5)]ethyl [(2)H(15)]octanoate.
  
  
  CONCLUSIONS
  Wine LAB exhibit ethyl ester-synthesizing capability and possess two different ester-synthesizing activities, one of which is associated with an acyl coenzyme A: alcohol acyltransferase.
  
  
  CONCLUSIONS
  This study demonstrates that wine LAB exhibit enzyme activities that can augment the ethyl ester content of wine. This knowledge will facilitate greater control over the impacts of malolactic fermentation on the fruity sensory properties and quality of wine.
authors.affiliation: The Australian Wine Research Institute, Glen Osmond, SA, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Costello
authors.forename: T E
authors.initials: TE
authors.lastname: Siebert
authors.forename: M R
authors.initials: MR
authors.lastname: Solomon
authors.forename: E J
authors.initials: EJ
authors.lastname: Bartowsky
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000217:Acyltransferases / Q000378:metabolism*; D002208:Caproates / Q000378:metabolism; D002210:Caprylates / Q000378:metabolism; D004950:Esterases / Q000378:metabolism*; D004952:Esters / Q000378:metabolism*; D000431:Ethanol; D005227:Fatty Acids / Q000378:metabolism; D005285:Fermentation; D005516:Food Microbiology; D005638:Fruit / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D048191:Lactiplantibacillus plantarum / Q000201:enzymology / Q000378:metabolism*; D056585:Oenococcus / Q000201:enzymology / Q000378:metabolism*; D014920:Wine / Q000382:microbiology*
chemical_list: D000214:Acyl Coenzyme A; D002208:Caproates; D002210:Caprylates; D004952:Esters; D005227:Fatty Acids; D000431:Ethanol; D000217:Acyltransferases; D004950:Esterases; C079237:ethyl hexanoate; C031492:octanoic acid