Biological activity of Bifidobacterium longum in response to environmental pH.
The influence of environmental pH on biological activity of Bifidobacterium longum CRL 849 grown in MRS-raffinose was evaluated. At pH 6.0, 5.5 and 5.0, raffinose was completely consumed by this microorganism, showing different consumption rates at each pH value (between 3.03 and 0.76 mmol l(-1) h(-1)). At pH 4.5, the growth was lowest. The removal of raffinose was due to the alpha-galactosidase (alpha-gal) activity of this bifidobacteria, which was highest at pH 6.0-5.5 (1,280-1,223 mU ml(-1)). The production of beta-glucosidase (beta-glu) showed a similar pattern to alpha-gal activity with major values. The yield of organic acids produced during raffinose consumption was also highest at pH 6.0-5.5. The results of this study will allow the selection of the optimum growth conditions of B. longum CRL 849, with elevated levels of alpha-gal to be used in the reduction of nondigestible alpha-oligosaccharide in soy products and beta-glu activities involved in isoflavone conversion to bioactive forms when used as starter culture.
Garro
Marisa S
MS
Centro de Referencia para Lactobacilos (CERELA-CONICET), Chacabuco 145, 4000 Tucumán, Argentina. mgarro@cerela.org.ar
Aguirre
Laura
L
Savoy de Giori
Graciela
G
D001644:Bifidobacterium / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D004777:Environment; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D011887:Raffinose / Q000378:metabolism; D000520:alpha-Glucosidases / Q000737:chemistry / Q000378:metabolism; D001617:beta-Glucosidase / Q000737:chemistry / Q000378:metabolism
D003470:Culture Media; D000520:alpha-Glucosidases; D001617:beta-Glucosidase; D011887:Raffinose