Effect of biosynthetic intermediates and citrate on the phenyllactic and hydroxyphenyllactic acids production by Lactobacillus plantarum CRL 778

ANDREA M. DALLAGNOL; CESAR A.N. CATALAN; MARIA I. MERCADO; GRACIELA FONT DE VALDEZ; GRACIELA C. ROLLAN

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 vol. 111 p. 1447 - 1455

1364-5072

Aim: 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 planta- rum CRL 778, a strain isolated from home-made sourdough.Methods and Results: Growth of fermentative activity and antifungal com- pounds production by Lact. plantarum CRL 778 were evaluated in a chemically defined medium (CDM) supplemented with biosynthetic precursors [phenylal- anine (Phe), tyrosine (Tyr)], intermediates [glutamate (Glu), alpha-ketogluta- rate (a-KG)] and electron acceptors [citrate (Cit)]. Results showed that the highest PLA production (0Æ26 mmol l)1), the main antifungal compound pro- duced 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 a-KG instead of Glu at similar Tyr⁄Phe molar ratio. Similarly, glutamate dehydrogenase (GDH) activity was signifi- cantly (P < 0Æ01) stimulated by a-KG and Cit in Glu-free medium.Conclusion: 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 a-KG and down regulated by Glu.Significance and Impact of the Study: 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.