title: Linoleate isomerase activity occurs in lactic acid bacteria strains and is affected by pH and temperature.
abstract: OBJECTIVE
  To investigate the ability of lactic acid bacteria (LAB) to convert linoleic acid (LA) and α-linolenic acid (α-LNA) to conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA), respectively. To assess pH and temperature influences on CLA and CLNA production by Lactobacillus sakei LMG 13558.
  
  
  RESULTS
  A screening of 48 LAB yielded one Lactobacillus curvatus, five Lactobacillus plantarum and four Lact. sakei strains displaying linoleate isomerase (LAI) activity. CLNA conversion percentages varied largely (1-60%). CLA conversion, occurring in three strains, was lower (2-5%). The LAI gene sequences of the ten LAI-positive strains shared 75-99% identity with the LAI gene sequence of a Lact. plantarum AS1.555. At pH 6.2, CLA and CLNA production by Lact. sakei LMG 13558 was higher at 30°C than at 20 and 25°C. At pH 5.5 (30°C) or 37°C (pH 6.2), LA was not converted and α-LNA only slightly converted.
  
  
  CONCLUSIONS
  LAB show strain-dependent LAI activity. Production of CLA and CLNA is affected by pH and temperature, as shown for Lact. sakei LMG 13558.
  
  
  CONCLUSIONS
  Several LAB produce CLA and/or CLNA, as shown for Lact. sakei and Lact. curvatus for the first time. These findings offer potential for the manufacturing of fermented functional foods.
authors.affiliation: Laboratory for Animal Nutrition and Animal Product Quality, Department of Animal Production, Ghent University, Melle, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Gorissen
authors.forename: S
authors.initials: S
authors.lastname: Weckx
authors.forename: B
authors.initials: B
authors.lastname: Vlaeminck
authors.forename: K
authors.initials: K
authors.lastname: Raes
authors.forename: L
authors.initials: L
authors.lastname: De Vuyst
authors.forename: S
authors.initials: S
authors.lastname: De Smet
authors.forename: F
authors.initials: F
authors.lastname: Leroy
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D005838:Genotype; D006863:Hydrogen-Ion Concentration; D007535:Isomerases / Q000235:genetics / Q000378:metabolism*; D007778:Lactobacillus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D019787:Linoleic Acid / Q000378:metabolism*; D044243:Linoleic Acids, Conjugated / Q000096:biosynthesis*; D010641:Phenotype; D013696:Temperature; D017962:alpha-Linolenic Acid / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D044243:Linoleic Acids, Conjugated; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid; D007535:Isomerases