Modulation of endogenous pathways enhances bioethanol yield and productivity in Escherichia coli

Table 2 Fermentation parameters for cell growth, sugar utilization and product synthesis at the bioreactor level

Sugar	Strain	Medium+Sugar Conc.^a	Product Yield (mmol per mmol sugar)						% Theoretical yield of ethanol^b	Max ethanol productivity^C
Sugar	Strain	Medium+Sugar Conc.^a	Cells	Succinate	Lactate	Formate	Acetate	Ethanol	% Theoretical yield of ethanol^b	Specific (mmol/g/h)	Volumetric (mmol/l/h)
Glucose	E. coli B	Defined medium+20 g/l	0.36	0.11	0.42	1.19	0.51	0.65	32	4.82	4.72
	SSY05	Defined medium+20 g/l	0.40	0.14	0.13	0.98	0.42	0.84	42	5.76	6.19
	SSY06	Defined medium+20 g/l	0.42	0.14	0.02	1.15	0.53	0.96	48	6.42	6.91
	SSY07	Defined medium+20 g/l	0.46	0.01	0.03	1.16	0.46	1.08	54	4.85	5.97
	SSY09(pZSack)	Defined medium+20 g/l	0.25	0.00	0.00	0.00	0.12	1.67	83	4.00	1.62
	E. coli B	LB medium+50 g/l	0.23	0.07	0.78	0.57	0.37	0.31	16	6.15	3.06
	SSY09(pZSack)	LB medium+50 g/l	0.16	0.01	0.01	0.03	0.07	1.89	95	20.03	12.34
Xylose	E. coli B	Defined medium+20 g/l	0.34	0.17	0.00	1.21	0.80	0.61	36	2.46	1.54
	SSY09(pZSack)	Defined medium+20 g/l	0.24	0.01	0.02	0.00	0.14	1.09	68	6.15	1.96
	E. coli B	LB medium+50 g/l	0.20	0.10	0.05	0.30	0.70	0.79	47	3.13	1.90
	SSY09(pZSack)	LB medium+50 g/l	0.18	0.02	0.01	0.03	0.26	0.91	55	1.57	1.67
	SSY09(pZSack)	LB medium+50 g/l (Microaerobic, pH 6.3)	0.40	0.01	0.01	0.01	0.17	1.63	97	5.72	6.84
Glucose+Xylose	SSY09 (pZSack)	LB medium+50 g/l (Microaerobic, pH 6.3)	0.64	0.01	0.00	0.00	0.04	1.61	85	5.43	14.94

^a Growth condition in the fermentor is described in materials and method section.
^b % Theoretical yield of ethanol was calculated by considering theoretical maximum yield of 2 mmol of ethanol per mmol of glucose and 1.67 mmol of ethanol per mmol of xylose as 100%.
^c Maximum specific (mmol ethanol per gram of cells per hour) and volumetric (mmol per liter of culture per hour) productivity of ethanol were calculated by accounting the interval at which maximum substrates were consumed and maximum products and cell biomass were formed.

ISSN: 1475-2859