Disruption of the gene encoding glutamate dehydrogenase affects growth, amino acids catabolism and survival of Lactobacillus plantarum UCC1001

The role played by glutamatedehydrogenase (GDH) in Lactobacillusplantarum was investigated by preparing a GDH-deficient mutant UC1001G. The growth rate and acidification displayed by this mutant were lower than those of the wild-type UC1001. Compared with UC1001G, UC1001 increased the synthesis of proteins that confer a competitive advantage of cell resistance. When both strains were used as adjunct starter for cheese-making, the highest cell survival was found for UC1001. Cheeses made with the adjunct of UC1001 showed the lowest level of free aminoacids and the highest content of volatile organic compounds. Both strains produced high level of γ-aminobutyric acid in cheese and under simulated gastrointestinal conditions. The findings of this study provide an evidence of the important role of GDH on growth and survival of Lb. plantarum under different environmental conditions that influences some important functional features of the strain.