title: Cell-adhered conjugated linoleic acid regulates isomerization of linoleic acid by resting cells of Propionibacterium freudenreichii.
abstract: The microbiological isomerization of linoleic acid (LA) to conjugated linoleic acid (CLA) was studied in resting cell suspensions of a propionibacterium and micellar LA to identify factors critical in the isomerization efficiency. These suspensions, containing cells 5x10(10) colony-forming units ml(-1) and 510 micro g LA ml(-1), isomerized about 90% of LA to CLA. However, the yield was not improved with higher amounts of micellar LA, suggesting that the cells had a fixed capacity to carry out the isomerization. This was explained by the fact that the CLA formed had a tendency to accumulate in the cell mass rather than in the aqueous micellar phase during the isomerization. Concomitantly, cell viability and isomerization rates were gradually reduced. Upon cessation of the reaction, about 46% of all the CLA formed was in the cell material. This accumulation to the cells was prevented by adding the detergent in excess to that required for micellization of LA. Then the cells remained viable, but the rate of isomerization was drastically lowered, due to impaired availability of LA from the fortified micellar phase to the cells. It was concluded that the phase distribution of substrate and product plays a critical role in the microbiological production of CLA.
authors.affiliation: Helsinki University of Technology, Department of Chemical Technology, Laboratory of Biochemistry and Microbiology, P.O. Box 6100, 02015 HUT, Finland. auli.rainio@hut.fi
authors.forename: A
authors.initials: A
authors.lastname: Rainio
authors.forename: M
authors.initials: M
authors.lastname: Vahvaselkä
authors.forename: S
authors.initials: S
authors.lastname: Laakso
mesh_terms: D004791:Enzyme Inhibitors / Q000494:pharmacology; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D019787:Linoleic Acid / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011424:Propionibacterium / Q000187:drug effects / Q000254:growth & development*
chemical_list: D004791:Enzyme Inhibitors; D019787:Linoleic Acid; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase