Table 7.

Production of glycolic acid (GA) by different E. coli strains in medium containing glucose and xylose as carbon sources

Strain name	Additional modifications	Plasmidsa	Biomass	GA	GA yield on consumed sugarb
			Yield [g/g]	Final conc. [g/l]	G + X [g/g]	G [g/g]	X [g/g]
Pen1042		pGS	0.30 ± 0.01	1.58 ± 0.11	0.37 ± 0.04	0.30 ± 0.05	0.47 ± 0.04
Pen1044		pGS + pX1P	0.26 ± 0.03	2.41 ± 0.64	0.42 ± 0.01	0.36 ± 0.09	0.49 ± 0.04
Pen1099	galP proD	pGS + pX1P	0.24 ± 0.00	1.29 ± 0.00	0.33 ± 0.00	0.36 ± 0.02	0.35 ± 0.02
Pen905	∆xylB	pGS + pX1P	0.22 ± 0.02	1.98 ± 0.68	0.47 ± 0.12	0.37 ± 0.12	0.60 ± 0.11
Pen979	∆xylB galP proD	pGS + pX1P	0.23 ± 0.02	3.73 ± 0.16	0.63 ± 0.04	0.40 ± 0.01	0.75 ± 0.05

All strains carried the deletions ∆aceB ∆glcDEFGB ∆gcl ∆edd-eda ΔiclR ΔarcA Δicd. Additional modifications are indicated in the table. Initial glucose and xylose concentrations were 2.5  and 5 g/l, respectively. The mineral medium was supplemented with 2 g/l tryptone and 1 g/l yeast extract

G glucose, X xylose, G + X total sugar

^a pGS expresses glyoxylate reductase and isocitrate lyase, encoded by ghrA and aceA. pX1P carries (d)-xylulose-1 kinase, (d)-xylulose-1 aldolase and glycolaldehyde dehydrogenase, encoded by khkC, aldoB and aldA, respectively. pACT3 is the empty plasmid

^b Results are presented as mean ± STDV calculated from at least two replicate experiments