Table 1.

Effect of calcium carbonate on ABE production by wild-type Clostridium sp. strain BOH3

Fermentation characteristicsa	Calcium carbonate (mM)
	0	5	10	30	50	70	100
Maximum dry cell weight (g/L)	3.4 ± 0.18	4.0 ± 0.23	4.9 ± 0.19	4.8 ± 0.20	4.7 ± 0.24	4.7 ± 0.21	4.5 ± 0.22
Butanol (g/L)	7.8 ± 0.13	9.5 ± 0.31	11.8 ± 0.24	11.6 ± 0.41	11.8 ± 0.32	11.4 ± 0.29	11.0 ± 0.35
Acetone (g/L)	3.8 ± 0.17	3.6 ± 0.25	3.3 ± 0.21	3.1 ± 0.21	3.0 ± 0.17	2.8 ± 0.15	2.6 ± 0.19
Ethanol (g/L)	0.7 ± 0.01	0.8 ± 0.02	0.9 ± 0.06	0.8 ± 0.05	0.7 ± 0.04	0.6 ± 0.02	0.6 ± 0.04
Acetate (g/L)	2.1 ± 0.07	3.8 ± 0.19	1.7 ± 0.04	1.5 ± 0.08	1.4 ± 0.06	1.1 ± 0.09	0.8 ± 0.07
Butyrate (g/L)	2.4 ± 0.11	3.4 ± 0.16	1.1 ± 0.01	0.7 ± 0.05	0.6 ± 0.07	0.8 ± 0.02	0.5 ± 0.03
Total solvent (g/L)	12.3 ± 0.5	13.9 ± 0.9	16.0 ± 1.1	15.5 ± 1.2	15.5 ± 0.8	14.8 ± 1.0	14.2 ± 0.9
pHalowest	3.9 ± 0.2	4.1 ± 0.1	4.8 ± 0.2	4.9 ± 0.3	5.1 ± 0.3	5.2 ± 0.2	5.3 ± 0.1
Final pH	4.7 ± 0.1	4.8 ± 0.2	5.0 ± 0.1	5.2 ± 0.2	5.3 ± 0.1	5.4 ± 0.2	5.5 ± 0.2
Butanol productivity (g/L h)	0.10 ± 0.01	0.13 ± 0.01	0.16 ± 0.01	0.16 ± 0.01	0.16 ± 0.01	0.16 ± 0.02	0.15 ± 0.02
Total starch hydrolysis rate (g/L h)	0.48 ± 0.02	0.59 ± 0.03	0.75 ± 0.02	0.73 ± 0.04	0.75 ± 0.03	0.75 ± 0.01	0.73 ± 0.04

^aNo pH adjustments