Table 4. Experimental results along the path of the steepest ascent for 24 h bottle fermentation at 35 ^oC with 130 rpm shaking.

Test	Glucose (g/L)	Yeast extract (g/L)	H2 yield (mol/mol) a
1	20	5.0	1.62 ± 0.12
2	18	5.5	1.63 ± 0.03
3	16	6.0	1.78 ± 0.02
4	14	6.5	1.51 ± 0.03
5	12	7.0	1.33 ± 0.02
6	10	7.5	1.31 ± 0.28
7	8	8.0	1.20 ± 0.01

^aValues were given by mean ± standard deviation (n = 3).