Knockout of the p-coumarate decarboxylase gene from Lactobacillus plantarum reveals the existence of two other inducible enzymatic activities involved in phenolic acid metabolism.
Lactobacillus plantarum NC8 contains a pdc gene coding for p-coumaric acid decarboxylase activity (PDC). A food grade mutant, designated LPD1, in which the chromosomal pdc gene was replaced with the deleted pdc gene copy, was obtained by a two-step homologous recombination process using an unstable replicative vector. The LPD1 mutant strain remained able to weakly metabolize p-coumaric and ferulic acids into vinyl derivatives or into substituted phenyl propionic acids. We have shown that L. plantarum has a second acid phenol decarboxylase enzyme, better induced with ferulic acid than with p-coumaric acid, which also displays inducible acid phenol reductase activity that is mostly active when glucose is added. Those two enzymatic activities are in competition for p-coumaric and ferulic acid degradation, and the ratio of the corresponding derivatives depends on induction conditions. Moreover, PDC appeared to decarboxylate ferulic acid in vitro with a specific activity of about 10 nmol. min(-1). mg(-1) in the presence of ammonium sulfate. Finally, PDC activity was shown to confer a selective advantage on LPNC8 grown in acidic media supplemented with p-coumaric acid, compared to the LPD1 mutant devoid of PDC activity.
Laboratoire de Microbiologie UMR-INRA, ENSBANA, Université de Bourgogne, Dijon, France.
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D002262:Carboxy-Lyases / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D003373:Coumaric Acids / Q000378:metabolism; D018274:Electroporation; D004790:Enzyme Induction; D017353:Gene Deletion; D006863:Hydrogen-Ion Concentration; D062385:Hydroxybenzoates / Q000378:metabolism*; D007778:Lactobacillus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010088:Oxidoreductases / Q000378:metabolism; D011422:Propionates
D003373:Coumaric Acids; D062385:Hydroxybenzoates; D011422:Propionates; C004999:ferulic acid; D010088:Oxidoreductases; D002262:Carboxy-Lyases; C087194:phenylacrylic acid decarboxylase; C017616:phenolic acid; C495469:p-coumaric acid