Effective isopropanol–butanol (IB) fermentation with high butanol content using a newly isolated Clostridium sp. A1424

Table 3 Isopropanol–butanol (IB) fermentation with various ratios of glucose and glycerol

	Ratio of glucose:glycerol (g:g)
	22:0	20:2	18:4	14:8^c	9:13^c
Substrate consumption
Glucose (g/L) [mM]	21.85_±0.27 [121.25]	19.85_±0.45 [110.16]	17.62_±0.69 [97.78]	13.35_±0.31 [74.10]	8.98_±0.20 [49.82]
Glycerol (g/L) [mM]	0 [0]	1.83_±0.61 [19.82]	3.59_±0.30 [38.97]	7.01_±0.14 [76.08]	10.94_±3.25 [118.79]
Total carbon (mM)	727.53	720.43	703.59	672.83	655.27
NAD(P)H from glycolysis (mM)	242.51	259.97	273.50	300.36	337.21
NAD(P)H_C (mol/mol)^d	0.33	0.36	0.39	0.45	0.51
Metabolite production
Butanol (g/L)	4.33_±0.00	4.66_±0.03	5.04_±0.08	5.38_±0.01	5.09_±0.09
Isopropanol (g/L)	2.44_±0.05	2.24_±0.03	2.07_±0.04	1.57_±0.02	0.83_±0.03
Acetone (g/L)	0.28_±0.00	0.18_±0.01	0	0	0
Butyric acid (g/L)	0.69_±0.02	0.73_±0.12	0.59_±0.00	0.98_±0.04	1.95_±0.03
Acetic acid (g/L)	0.51_±0.00	0.46_±0.00	0.43_±0.00	0.24_±0.02	0.11_±0.02
NAD(P)H requirement for product (mM)	290.02	305.35	319.82	338.44	332.62
Ratio of B/I^a (g/g)	1.78	2.07	2.43	3.43	6.14
Y ^b_B (g/g)	0.20	0.21	0.24	0.26	0.26
Y ^b_IB (g/g)	0.31	0.32	0.34	0.34	0.30

The values are average and one standard deviation of triplicate experiments
The fermentation was performed on serum bottle without pH control
The data were obtained at 28 h of fermentation except 9:13 (25 h)
^aB/I butanol concentration divided by isopropanol concentration
^b Y _B, butanol yield (g butanol/g substrate); Y _IB, the sum of butanol and isopropanol yield (g [butanol + isopropanol]/g substrate)
^cAfter fermentations, 0.39 and 2.48 g/L glycerol remained on the ratio of 14:8 and 9:13, respectively
^dNAD(P)H_C: The generation of NAD(P)H mole per consumed substrate carbon mole

ISSN: 2731-3654