Effect of biosynthetic intermediates and citrate on the phenyllactic and hydroxyphenyllactic acids production by Lactobacillus plantarum CRL 778
2011
Dallagnol, A.M. | Catalán, C.A.N. | Mercado, M.I. | Font de Valdez, G. | Rollán, G.C.
Aim: To evaluate the influence of biosynthetic precursors, intermediates and electron acceptors on the production of antifungal compounds [phenyllactic acid (PLA) and hydroxyphenyllactic acid (OHâPLA)] by Lactobacillus plantarum CRL 778, a strain isolated from homeâmade sourdough. Methods and 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), alphaâketoglutarate (αâKG)] and electron acceptors [citrate (Cit)]. Results showed that the highest PLA production (0·26âmmolâl−1), the main antifungal compound produced by Lact. plantarum CRL 778, occurred when greater concentrations of Phe than Tyr were present. Both PLA and OHâPLA yields were increased 2âfolds when Cit was combined with αâKG instead of Glu at similar Tyr/Phe molar ratio. Similarly, glutamate dehydrogenase (GDH) activity was significantly (Pâ<â0·01) stimulated by αâKG and Cit in Gluâfree medium. Conclusion: Phe was the major stimulant for PLA formation; however, Cit could increase both PLA and OHâPLA 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 αâKG 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 OHâPLA 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.
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