Enhancement of D-lactic acid production from a mixed glucose and xylose substrate by the Escherichia coli strain JH15 devoid of the glucose effect

Table 1 Fermentations summary by E. coli JH13 and JH15

Strain	Substrate (100 g L⁻¹)	Fermentation Time (h)	Sugar consumption (g L⁻¹ h⁻¹)^a						Lactic acid production (g L⁻¹ h⁻¹)^b
			Glucose		Xylose		Total (glu + xyl)		Titer (g L⁻¹)	Yield (%)	Vol. productivity (g L⁻¹ h⁻¹)
			Max	Average	Max	Average	Max	Average	Titer (g L⁻¹)	Yield (%)	Max	Average
JH13	Glucose	28	5.88	3.36					85	90	5.44	3.04
	Xylose	91			1.65	0.95			84	83	1.63	0.93
	Glu + Xyl	114	3.42	2.08	0.6	0.39	n/a^c	0.71	66	80	n/a³⁾	0.58
JH15	Glucose	36	2.88	2.69					88	91	3.75	2.44
	Xylose	120			1.38	0.8			81	83	1.13	0.67
	Glu + Xyl	96	1.89	1.28	0.95	0.52	2.2	1.04	83	83	2.53	0.86

^aThe maximum sugar consumption was calculated from the fastest 8 h, or longer, fermentation period. The average sugar consumption was calculated from the active fermentation period (0 h to the end of fermentation)
^bThe yield was calculated based on lactic acid produced over sugar metabolized. The maximum lactic acid productivity was calculated from the fastest 8 h, or longer, fermentation period. The average lactic acid productivity was calculated from the active production period (0 h to the end of fermentation)
^cn/a is not applicable (since glucose and xylose was used separately in JH13, the maximum total sugar consumption and maximum lactic acid productivity would be derived from glucose fermentation only)

ISSN: 1472-6750