TABLE 4.

Physiology of S. bulderi in anaerobic δ-gluconolactone-limited chemostat cultures at a dilution rate of 0.05 h⁻¹ and at different culture pH^a

pH	Ysx	CO2/ethanol ratio	qs	qCO2	qethanol	qglycerol	qpyruvate	qacetate	qlactate	C recovery (%)
2.5	0.060	1.27	5.25	10.2	8.1	0.75	<0.01	0.08	0.07	98.9
3.0	0.074	1.33	4.10	8.2	6.2	0.68	0.03	0.03	0.11	102.8
3.5	0.070	1.33	4.49	8.6	6.5	0.73	<0.01	0.03	0.09	97.6
4.0	0.074	1.34	4.08	7.8	5.8	0.70	<0.01	0.04	0.09	98.0
4.5	0.075	1.37	4.06	8.1	5.9	0.70	<0.01	0.07	0.08	100.7
5.0	0.071	1.38	4.32	8.6	6.2	0.81	<0.01	0.12	0.09	102.4
Avg	0.070	1.34	4.38	8.6	6.5	0.73	<0.01	0.06	0.09	100.0

^aSpecific rates of substrate consumption (q_s) and metabolite production (q) are presented as millimoles per gram of biomass per hour. The CO₂-to-ethanol ratio equals the quotient of the specific rates of production of these metabolites. The biomass yield on a substrate (Y_sx) is given as grams of biomass per gram of substrate utilized (i.e., the reservoir substrate concentration minus the residual concentration in the culture). Data were calculated as described in Materials and Methods and are the average of two independent cultivations at each pH. Data from these independent replicate experiments differed by less than 5%.