Bifidobacterium longum ATCC 15707 cell production during free- and immobilized-cell cultures in MRS-whey permeate medium
2002
Doleyres, Y. | Paquin, C. | Leroy, M. | Lacroix, C.
Bifidobacterium longum ATCC 15707 cell production was studied in MRS medium supplemented with whey permeate (MRS-WP) during free-cell batch fermentations and continuous immobilized-cell cultures. Very high populations were measured after 12 h batch cultures in MRS-WP medium controlled at pH 5.5 (1.7 +/- 0.5x10(10) cfu/ml), approximately 2-fold higher than in non-supplemented MRS. Our study showed that WP is a low-cost source of lactose and other components that can be used to increase bifidobacteria cell production in MRS medium. Continuous fermentation in MRS-WP of B. longum immobilized in gellan gum gel beads produced the highest cell concentrations in the effluent (4.9 +/- 0.9x10(9) cfu/ml) at a dilution rate (D) of 0.5 h-1. However, maximal volumetric productivity (6.9 +/- 0.4x10(9) cfu ml-1h-1) during continuous cultures was obtained at D = 2.0 h-1, and was approximately 9.5-fold higher than during free-cell batch cultures at an optimal pH of 5.5 (7.2x10(8) cfu ml-1h-1).
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