alpha-Ketoglutarate biosynthesis in wild and industrial strains of Lactococcus lactis.
OBJECTIVE
This study was carried out to explore the ability of wild and industrial strains of Lactococcus lactis to produce alpha-ketoglutarate (alpha-KG), which is essential during the conversion of amino acids to flavour compounds.


RESULTS
Two pathways in alpha-KG biosynthesis were explored in strains of L. lactis isolated from dairy products, vegetables and commercial dairy starter cultures. Half of the strains efficiently converted glutamine to glutamate (Glu) and grew in Glu-free medium. Strains did not present isocitrate dehydrogenase and aconitase activities. However, half of the strains presented glutamate dehydrogenase (GDH) activity.


CONCLUSIONS
The ability of L. lactis to synthesize either alpha-KG or Glu via GDH was confirmed. However, L. lactis strains were not able to biosynthesize alpha-KG by the citrate-isocitrate pathway. NADP-GDH activity was mainly found in strains isolated from vegetables, whereas NAD-GDH activity was mainly found in strains isolated from dairy products.


CONCLUSIONS
The origin of isolation highly influenced NAD or NADP-GDH activities. These enzymatic activities may be correlated to the flavour production capacity of the different strains.
Gutiérrez-Méndez
N
N
Centro de Investigación en Alimentación y Desarrollo A.C. (CIAD, A.C.), Carretera a la Victoria Km. 0.6, Hermosillo, Sonora, México.
Valenzuela-Soto
E
E
González-Córdova
A F
AF
Vallejo-Cordoba
B
B
D005969:Glutamate Dehydrogenase / Q000502:physiology; D018698:Glutamic Acid / Q000096:biosynthesis; D007656:Ketoglutaric Acids / Q000378:metabolism*; D013294:Lactococcus lactis / Q000254:growth & development / Q000378:metabolism*; D009249:NADP / Q000378:metabolism
D007656:Ketoglutaric Acids; D018698:Glutamic Acid; D009249:NADP; D005969:Glutamate Dehydrogenase