Nitrogen metabolic profile of Lactococcus lactis subsp. cremoris strains under stress conditions

摘要

Lactococcus lactis subsp. cremoris MG1363 is an international prototype for genetic and physiological studies in lactic acid bacteria. The aim of this study was to determine and evaluate changes in the production of extracellular metabolites generated in aminoacidic routes by the species L. lactis subsp. cremoris in response to the stress due to the presence of ethanol in the culture medium. We analyzed aminoacids generated by the strain L. lactis subsp. cremoris MG1363 and three mutants: MGΔargR, MGΔahrC and MGAargRΔahrC under different culture conditions. Results showed that L. lactis subsp. cremoris used arginine to grow in the presence of ethanol in the medium, using the ADI pathway and producing ornithine as final product of degradation, concluding that L. lactis subsp. cremoris utilized the ADI arginine degradation pathway as a response to the ethanol stress, producing ornithine as the final metabolic product.