Glutamate dehydrogenase activity can be transmitted naturally to Lactococcus lactis strains to stimulate amino acid conversion to aroma compounds.

Amino acid conversion to aroma compounds by Lactococcus lactis is limited by the low production of alpha-ketoglutarate that is necessary for the first step of conversion. Recently, glutamate dehydrogenase (GDH) activity that catalyzes the reversible glutamate deamination to alpha-ketoglutarate was detected in L. lactis strains isolated from a vegetal source, and the gene responsible for the activity in L.

The specificity of oligopeptide transport by Streptococcus thermophilus resembles that of Lactococcus lactis and not that of pathogenic streptococci.

Peptide transport is a crucial step in the growth of Streptococcus thermophilus in protein- or peptide-containing media. The objective of the present work was to determine the specificity of peptide utilization by this widely used lactic acid bacterium. To reach that goal, complementary approaches were employed.

Ability of thermophilic lactic acid bacteria to produce aroma compounds from amino acids.

Although a large number of key odorants of Swiss-type cheese result from amino acid catabolism, the amino acid catabolic pathways in the bacteria present in these cheeses are not well known. In this study, we compared the in vitro abilities of Lactobacillus delbrueckii subsp. lactis, Lactobacillus helveticus, and Streptococcus thermophilus to produce aroma compounds from three amino acids, leucine, phenylalanine, and methionine, under mid-pH conditions of cheese ripening (pH 5.

Proteome analyses of heme-dependent respiration in Lactococcus lactis: involvement of the proteolytic system.

Sugar fermentation was long considered the sole means of energy metabolism available to lactic acid bacteria. We recently showed that metabolism of Lactococcus lactis shifts progressively from fermentation to respiration during growth when oxygen and heme are available. To provide insights into this phenomenon, we compared the proteomic profiles of L.

Three oligopeptide-binding proteins are involved in the oligopeptide transport of Streptococcus thermophilus.

The functions necessary for bacterial growth strongly depend on the features of the bacteria and the components of the growth media. Our objective was to identify the functions essential to the optimum growth of Streptococcus thermophilus in milk. Using random insertional mutagenesis on a S.