High titer and yield ethanol production from undetoxified whole slurry of Douglas-fir forest residue using pH profiling in SPORL

Table 3 Comparisons of fermentation performance among pretreatments with and without pH profiling.

	Control ( t _i = 0)	pH profiling ( t _i = 25 min)	pH profiling ( t _i = 45 min)
Average fermentation performance measure (g/L/h)
Glucose consumption (72 h)	−0.54 ± 0.06	−0.70 ± 0.07	−0.64 ± 0.05
Ethanol productivity (72 h)	0.42 ± 0.03	0.50 ± 0.02	0.51 ± 0.02
HMF metabolization (24 h)	−0.05 ± 0.002	−0.03 ± 0.002	−0.02 ± 0.006
Maximal ethanol production
Terminal ethanol concentration (g/L)	38.6 ± 7.5	48.9 ± 1.4	45.9 ± 4.6
Ethanol yield (g g/sugar)^a	0.390 ± 0.076	0.494 ± 0.014	0.460 ± 0.046
Ethanol yield (L/tonne wood)^b	215 ± 42	297 ± 9	259 ± 26
Ethanol yield (% theoretical)^c	52.8 ± 10.3	73.1 ± 2.1	63.7 ± 6.4

^aBased on the total of glucan, mannan, and xylan in the pretreated-solids and glucose, mannose, and xylose in the pretreatment spent liquor.
^bCalculated from measured amount of ethanol yield from the amount of pretreated whole slurry used in fermentation and the yield of whole slurry from pretreatment.
^cTheoretical yield (406 L tonne wood⁻¹) based on total glucan, mannan, and xylan in the untreated forest residue of FS10.

ISSN: 2731-3654