title: Effect of biosynthetic intermediates and citrate on the phenyllactic and hydroxyphenyllactic acids production by Lactobacillus plantarum CRL 778.
abstract: OBJECTIVE
  To evaluate the influence of biosynthetic precursors, intermediates and electron acceptors on the production of antifungal compounds [phenyllactic acid (PLA) and hydroxyphenyllactic acid (OH-PLA)] by Lactobacillus plantarum CRL 778, a strain isolated from home-made sourdough.
  
  
  RESULTS
  Growth of fermentative activity and antifungal compounds production by Lact. plantarum CRL 778 were evaluated in a chemically defined medium (CDM) supplemented with biosynthetic precursors [phenylalanine (Phe), tyrosine (Tyr)], intermediates [glutamate (Glu), alpha-ketoglutarate (α-KG)] and electron acceptors [citrate (Cit)]. Results showed that the highest PLA production (0.26 mmol l(-1)), the main antifungal compound produced by Lact. plantarum CRL 778, occurred when greater concentrations of Phe than Tyr were present. Both PLA and OH-PLA yields were increased 2-folds when Cit was combined with α-KG instead of Glu at similar Tyr/Phe molar ratio. Similarly, glutamate dehydrogenase (GDH) activity was significantly (P < 0.01) stimulated by α-KG and Cit in Glu-free medium.
  
  
  CONCLUSIONS
  Phe was the major stimulant for PLA formation; however, Cit could increase both PLA and OH-PLA synthesis by Lact. plantarum CRL 778 probably due to an increase in oxidized NAD(+). This effect, as well as the GDH activity, was enhanced by α-KG and down regulated by Glu.
  
  
  CONCLUSIONS
  This is the first study where the role of Glu and GDH activity in the PLA and OH-PLA synthesis was evidenced in sourdough lactic acid bacteria (LAB) using a CDM. These results contribute to the knowledge on the antifungal compounds production by sourdough LAB with potential applications on the baked goods.
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA-CONICET), S. M. de Tucumán, Argentina.
authors.forename: A M
authors.initials: AM
authors.lastname: Dallagnol
authors.forename: C A N
authors.initials: CA
authors.lastname: Catalán
authors.forename: M I
authors.initials: MI
authors.lastname: Mercado
authors.forename: G
authors.initials: G
authors.lastname: Font de Valdez
authors.forename: G C
authors.initials: GC
authors.lastname: Rollán
mesh_terms: D002951:Citrates / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D018698:Glutamic Acid / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism; D007773:Lactates / Q000378:metabolism*; D048191:Lactiplantibacillus plantarum / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D010666:Phenylpropionates / Q000378:metabolism*
chemical_list: D002951:Citrates; D003470:Culture Media; D007656:Ketoglutaric Acids; D007773:Lactates; D010666:Phenylpropionates; C001418:4-hydroxyphenyllactic acid; D018698:Glutamic Acid; D010649:Phenylalanine