Effect of pH on Lactobacillus fermentum growth, raffinose renoval, alpha-galactosidase activity and fermentation products

LEBLANC, J. G.; GARRO, M. S.; S. DE GIORI, GRACIELA

APPLIED MICROBIOLOGY AND BIOTECHNOLOGY

Springer-Verlag

Lugar: Berlin; Año: 2004 vol. 65 p. 119 - 123

0175-7598

Abstract: In this study, the behaviour of Lactobacillus fermentum CRL 722 and CRL 251 were evaluated under different pH conditions (pH 6.0, 5.5, 5.0, 4.5) and without pH control. Growth was similar under all conditions assayed except at pH 4.5. These microorganisms were able to eliminate raffinose, a nondigestible á-oligosaccharide (NDO) found in soy products, showing a consumption rate of 0.25 g l-1 h-1 (pH 6.0–5.0). The removal of raffinose was due to the high alpha-galactosidase (alpha-gal) activities of these lactic acid bacteria, which was highest at pH 5.5 (5.0 U/ml). The yield of organic acids produced during raffinose consumption was also highest at this pH. The results of this study will allow selection of the optimum growth conditions of L. fermentum with elevated levels of alpha-gal to be used in the reduction of NDO in soy products when used as starter cultures.