A novel pyruvate kinase and its application in lactic acid production under oxygen deprivation in Corynebacterium glutamicum

Table 1 The production of organic acids by C. glutamicum strains under oxygen deprivation^a

Strains	Glucose (mM/h)	Lactic acid (mM)	Succinic acid (mM)	Acetic acid (mM)	Lactic acid Yield (%)^b	Pyk activity (mU/mg)^c
WT	28.46 ± 0.56	126.18 ± 1.70	22.59 ± 1.65	5.17 ± 0.05	73.90 ± 0.99	471.06 ± 6.61 (418.56 ± 6.54)*
WTΔpyk1	27.72 ± 0.28	109.90 ± 4.00*	44.49 ± 0.88*	5.89 ± 0.91	66.09 ± 2.41*	69.98 ± 5.00* (11.34 ± 0.42)*
WTΔpyk2	29.75 ± 0.11	117.30 ± 2.31*	38.02 ± 0.82*	5.35 ± 0.76	65.71 ± 1.29*	402.29 ± 8.98* (406.87 ± 14.69)
WTΔpyk1Δpyk2	28.83 ± 0.38	98.80 ± 1.11*	47.83 ± 0.86*	6.06 ± 0.64	57.12 ± 0.64*	ND (ND)
WTΔpyk1Δpyk2/pXMJ19	29.51 ± 0.43	99.17 ± 2.31*	49.45 ± 1.69*	4.40 ± 1.80	56.02 ± 1.30*	ND
WTΔpyk1Δpyk2/pXMJ19-pyk1	29.81 ± 0.85	127.29 ± 3.57	28.42 ± 3.13*	6.30 ± 2.19	71.16 ± 1.99	472.94 ± 21.29
WTΔpyk1Δpyk2/pXMJ19-pyk2	29.69 ± 1.20	128.77 ± 2.22	29.11 ± 5.13*	6.23 ± 2.07	72.28 ± 1.25	442.72 ± 10.64
WT/pXMJ19	29.63 ± 0.56	125.44 ± 4.00	27.59 ± 0.76*	6.72 ± 1.16	70.56 ± 2.25	486.38 ± 31.68
WT/pXMJ19-pyk1	32.78 ± 0.74*	150.98 ± 2.94*	13.37 ± 0.14*	12.78 ± 1.29*	76.77 ± 1.49*	926.55 ± 63.96*
WT/pXMJ19-pyk2	33.58 ± 0.28*	146.17 ± 3.20*	19.20 ± 1.27*	15.38 ± 0.89*	72.54 ± 1.59	911.45 ± 31.86*

^aThe cells were suspended to a final dry cell weight of 10 g/L in 100 mL of CGXII medium with 100 mM bicarbonate. The values were analyzed after 3 h under oxygen deprivation. The data were derived from experiments performed at least in three times, and the error bars represent the standard deviations
^bThe yields were calculated as a percentage of the theoretical yield (100% represented 2 mol of lactic acid per 1 mol of glucose consumed)
^cPyk activities were measured under oxygen deprivation as described above. And the values in parentheses show the Pyk activities at the exponential growth phase under aerobic conditions. ND, not detected
*,significant differences between WT and mutants under oxygen deprivation analyzed by t-test (P < 0.05) were marked. And the differences of Pyk activities of strains between aerobic and oxygen-deprived conditions are also shown (P < 0.05)

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