Increased 3-hydroxypropionic acid production from glycerol, by modification of central metabolism in Escherichia coli

Table 1 Summary of the experimental results

	TK52	TK52z	TK52t	TK52tz	TK52tzy	Simulation^*4 iAF1260-3HP	Simulation^4 ΔtpiA Δzwf*
Specific growth rate (1/h)^*1	0.73 ± 0.00	0.71 ± 0.00	1st: 0.55 ± 0.01	1st: 0.54 ± 0.01	1st: 0.56 ± 0.01
Specific growth rate (1/h)^*1	0.73 ± 0.00	0.71 ± 0.00	2nd: 0.03 ± 0.01	2nd: 0.03 ± 0.00	2nd: 0.04 ± 0.01
Maximum 3HP production rate (mmol/(g DC●h))^*2	0.08 ± 0.02	0.09 ± 0.01	0.22 ± 0.14	0.27 ± 0.11	0.94 ± 0.05
Consumed glycerol (mM)^*3	192.7 ± 5.0	193.2 ± 2.4	168.2 ± 24.4	119.0 ± 44.6	117.6 ± 3.9
Biomass (C-mol%)^*3	37.0 ± 3.5	36.1 ± 1.4	19.6 ± 3.2	21.7 ± 11.0	20.8 ± 1.2	47.7	22.8
	(5.2 ± 0.5)	(5.1 ± 0.2)	(2.4 ± 0.6)	(1.6 ± 0.3)	(1.8 ± 0.1)
3HP (C-mol%)^*3	4.6 ± 0.8	5.7 ± 0.6	14.7 ± 7.0	20.1 ± 9.2	33.9 ± 1.2	0	70.5
	(8.9 ± 1.3)	(11.1 ± 1.0)	(24.3 ± 11.7)	(21.2 ± 7.7)	(39.9 ± 2.4)
1,3-PDO (C-mol%)^*3	0.8 ± 0.4	0.7 ± 0.2	22.9 ± 5.2	37.7 ± 13.2	5.9 ± 0.5	0	0
	(1.5 ± 0.8)	(1.3 ± 0.3)	(38.1 ± 9.4)	(40.5 ± 14.0)	(7.0 ± 0.7)
Succinate (C-mol%)^*3	0.9 ± 0.1	1.3 ± 0.2	0.3 ± 0.3	0	0	0	0
	(1.3 ± 0.2)	(1.9 ± 0.2)	(0.4 ± 0.3)	(0)	(0)
Acetate (C-mol%)^*3	9.9 ± 1.8	12.9 ± 0.2	8.2 ± 9.9	2.2 ± 4.1	6.6 ± 1.9	27.4	0
	(28.7 ± 5.4)	(37.3 ± 1.1)	(20.5 ± 24.3)	(5.1 ± 9.6)	(11.6 ± 3.0)
Maximum methylglyoxal concentration (mM)	0.03 ± 0.02	0.03 ± 0.02	0.29 ± 0.02	0.22 ± 0.02	0.60 ± 0.02

^*1Specific growth rates were calculated using OD₆₀₀ at 0–6 h for the TK52 and TK52z strains. For the TK52t, TK52tz and TK52tzy strains, specific growth rates during the 1st and 2nd growth phases were calculated using the OD₆₀₀ at 0–6 h and 48–72 h, respectively.
^*2Maximum 3HP production rates were calculated from the data at 24–48 h for the TK52 and TK52z strains, and at 48–72 h for other strains.
^*3C-mol% was calculated from the carbon-mol of the product per carbon-mol of the consumed glycerol. The values in the parentheses indicate the final concentrations of biomass (g/L) and products (mM). Standard deviations were obtained from triplicate experiments in the TK52 and TK52z strains, and from 9 replicate experiments in other strains. For calculation of biomass yield, OD₆₀₀ was converted into dry cell weight using the conversion factor 0.37 g DC/L, and carbon-mol in the biomass was calculated based on the biomass composition described in the iAF1260 model [21].
^*4Metabolic simulation was performed with following parameters: GUR was 15 mmol/(g DC●h) and OUR was 10 mmol/(g DC●h).

ISSN: 1475-2859