Investigation of two metabolic engineering approaches for (R,R)-2,3-butanediol production from glycerol in Bacillus subtilis

Table 3 Comparison of flux distribution predicted by different engineering approaches for different strains (reaction unit: mmol/gCDW/h)^a

Method	OptKnock^b	Two-step FBA^c	Single-level FBA
*B. subtilis* strain	W168	W168	MZ02^d
Biomass production	0.35	0.30	0.28
Acetate exchange	0.15	3.12	0.12
l-Lactate exchange	0.00	0.00	4.69
(R,R)-2,3-BD exchange	2.10	1.35	0.00

^aGlycerol utilization and oxygen consumption were set to 10 mmol/gCDW/h (see Methods)
^bOptKnock objectives were set for growth coupling with 2,3-BD production. The reactions suggested for gene knockout were: ACKr (ack), PTAr (pta), ACACT1r (mmgA), G6PDH2r (zwf)
^cTwo-step FBA was conducted with the production flux of the target compound maximized with the biomass growth rate, which was fixed at its maximum value. Specifically, the element corresponding to the production of the target compound in a column array containing the objective function coefficients was set to 10⁻⁵
^dMZ02 was designed to be unable to perform four reactions, namely, ACKr (ack), PTAr (pta), ACACT1r (mmgA), and G6PDH2r (zwf)

ISSN: 1754-1611