INVESTIGADORES
ALARCON Sergio Hugo
congresos y reuniones científicas
Título:
Inactivation of the glutamate dehydrogenase activity in Lb. casei and its effect on growth and flavor generation
Autor/es:
PABLO MORTERA; FEDERICO ZULJAN; SERGIO ALARCON; CHRISTIAN MAGNI
Reunión:
Congreso; L Reunión Anual. Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2014
Resumen:
Lactobacillus
casei is one of the strains commonly used in adjunct cultures for the cheese
ripening contributing to the final organoleptic characteristics. The amino
acids (AA) catabolism contributes to the flavor production being the glutamate
a key compound in the recycling and conversion of α-ketoacids. From these
compounds, the AA are sources of organic acids, alcohols, aldehydes, ketones
and esters which give food flavor. The α-ketoglutarate regeneration by
glutamate dehydrogenase (GDH), has been reported be a desired activity of
adjunct cultures. We evaluated the role of GDH in the flavor generation from AA
metabolism, and the survival and growth on different carbon and nitrogen
sources. For that, we made a mutant strain of Lb. casei with the gdh gene
disrupted and its phenotype was compared with that of the wild type (WT)
strain. The growth of the mutant and WT strain was evaluated in MRS medium
using different carbon and nitrogen sources. The aroma production was assessed
in resting cells through the solid-phase microextraction (SPME) system followed
by gas chromatographic separation coupled to a mass spectrometer as detector
(GC-MS). The relative AT activities of the cell-free extracts was also
evaluated. This study provide further evidence of the role and importance of
GDH for AA catabolism and survival of Lb casei under different carbon and
nitrogen sources.