Efficient hydrogen production from the lignocellulosic energy crop Miscanthus by the extreme thermophilic bacteria Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana

Table 6 Fermentation parameters of 1 l batch cultures of C. saccharolyticus at 72°C and T. neapolitana at 80°C grown on a glucose/xylose (7:3, w w^-1) mixture and on Miscanthus hydrolysate.

Mono-saccharides	Ferm. period	Consumption			Production						C-balance	COD-balance
			mmol l^-1		mmol l^-1					g l^-1
g l^-1	h	Glucose	Xylose	COD	H₂	CO₂	Acetate	Lactate	COD	CDW
C. saccharolyticus
Glc/Xyl
10	28	39.3	18.7		188	100	88.8	1.1		0.67	0.94	0.93
14	34	55.2	25.4		253	130	117	1.9	7.4	0.77	0.87	0.91
28	>71	77.4	54.8		293	171	136	3.7	53.1	0.84	0.66	0.79
Hydrolysate
10	35	41.9	17.5	82.6	237	120	105	1.1		0.98	0.89	0.92
14	69	58.9	26.2	92.8	319	176	152	2.3		1.04	0.92	0.92
28	>71	52.4	41.5	97.9	244	153	125	4.5		1.01	0.74	0.88
T. neapolitana
Glc/Xyl
10	22	38.2	18.6		178	93.6	82.3	3.9		0.97	0.96	0.94
14	33	54.4	24.4		240	131	105	5.9	15.8	0.74	0.87	0.91
28	>45	66.7	21.3		189	113	89.9	14.2	58.4	0.42	0.81	0.90
Hydrolysate
10	26	40.8	16.0	80.3	198	102	88.0	9.6		1.27	0.89	0.92
14	39	55.8	22.2	94.3	285	154	124	11.2		1.02	0.88	0.91
28	>45	42.9	22.8	-^a	82.0	62.2	45.2	11.2	124	0.46	0.89	0.96

^aDue to Maillard reactions and thus non-defined product formation, no net chemical oxygen demand (COD) consumption was measured.

ISSN: 1754-6834