Enhanced organically bound chromium yeast production.

ABSTRACT

This paper describes continuous and fed-batch fermentation protocols for enhanced production of organically bound chromium yeast. During continuous fermentation, several inorganic chromium compounds were evaluated. Sodium chromate demonstrated the best chromium incorporation into yeast biomass without any precipitation in the fermentation medium. During fed-batch fermentation, several sodium chromate concentrations were evaluated at 1.1, 3.5, 5.9, 7.1, 8.3, and 10.8 g/L with continuous or single-dose addition. For single-dose addition of sodium chromate, some precipitation was observed for all concentrations, which reduced the available chromium in the fermentation medium. Adapted strain C11-1, obtained during continuous fermentation, produced higher biomass than the wild type but significantly lowered chromium incorporation. Pilot-scale fermentation demonstrated similar total chromium incorporation (2966 ppm) with lower biomass production compared to benchtop fermentation performed at the same sodium chromate addition.