The improvement of glucose/xylose fermentation by Clostridium acetobutylicum using calcium carbonate

摘要: Batch fermentation of 60g/l glucose/xylose mixture by Clostridium acetobutylicum ATCC 824 was investigated on complex culture medium. Different proportions mixtures, ranged between 10 and 50g each sugar/l, were fermented during pH control at 4.8 (optimum for solventogenesis) or CaCO3 addition. Using xylose-pregrown cells control, an important amount xylose left over the end when glucose concentration higher than that xylose. The addition 10g CaCO3/l (to prevent dropping below 4.8) increased uptake: a substantial decrease residual observed as well glucose-pregrown used inoculum all studied. MgCO3 (Mg2+-containing compound) CaCl2 (Ca2+-containing reduced only NaOH As butanol is major limiting factor uptake in C. acetobutylicum, fermentations carried out with without butanol-containing media iron deficient (under limitation, synthesis occurred early could inhibit uptake). Results showed excess CaCOCaCO3 increase tolerance which resulted utilization. This positive effect seem to be specific Ca2+- Mg2+-containing compounds, going beyond buffering carbonate.