Table 1.

Ethanol concentration and yield at different feed methods using fed-batch S-SSF

Trial number	Dry weight (g) of WIS fed at different times b			Volume of fermentation broth (mL) after feeding a		Reed straw			Corn stover
	At 6 hours of pre-hydrolysis	At 16 hours of pre-hydrolysis	At 6 hours of fermentation	Reed straw	Corn stover	Ethanol concentration (g/L)	Ethanol yield (%)	Ethanol yield (g/kg feedstock)	Ethanol concentration (g/L)	Ethanol yield (%)	Ethanol yield (g/kg feedstock)
1	1	-	-	11.44	11.60	41.21 ± 1.42	74.4	248	39.20 ± 2.84	70.3	230
2	1	0.5	-	12.16	12.40	46.23 ± 2.84	71.0	237	51.26 ± 1.42	78.6	257
3	1	1	-	12.88	13.20	41.21 ± 1.42	55.9	186	52.26 ± 2.84	71.1	233
4	1	0.5	0.5	12.88	13.20	53.27 ±1.42	72.3	241	47.24 ± 1.42	64.3	211
5	1	1	0.5	13.60	14.00	56.28 ± 0	69.1	197	52.26 ± 0	64.6	212

^aCalculated value based on water content of fed WIS. The moisture of fed WIS was 59.02% for reed straw and 61.60% for corn stover; ^bweight of initial WIS was 1 g in the S-SSF. The Tween 40 pretreatment conditions were as follows: Tween 40 concentration, 1.5%; ratio of WIS-to-Tween 40, 1:10 (w/v); pretreatment temperature, 25°C; and pretreatment time, 1 hour. The fed-batch S-SSF conditions were as follows: cellulase loading, 25 FPU/g oven-dried WIS; pre-hydrolysis temperature, 50°C; pre-hydrolysis time, 18 hours; fermentation temperature, 36°C; and fermentation time, 72 hours. S-SSF, semi-simultaneous saccharification and fermentation.