Table 3.

Comparison of simultaneous saccharification and fermentation methods using SO₂ pretreatment of softwoods with Saccharomyces cerevisiae strains

Yeast straina	Wood type	Pretreatmentb			Solids, % dry weight/volume	Inoc, g/L	Cellulase, FPU/gram dry weight	Max EtOH, g/L	Time to maximum EtOH production, hours	% TM	Reference
		SO2 conc.	Reaction temp, °C	Duration, min
Tembec 1	Lodgepole pine	4.0	200	5	5% (washed)	5	40 FPU/g cellulase, 20 CU/g cellobiase	17.0	24	68c	Ewanick et al. [36] (note: 6 hours enzyme preincubation)
Tembec 1	Douglas fir	4.5	195	4.5d	40 mL, WSF	5	No enzymes added	13.8	24	87e	Keating et al. [37]
Y-1528	Douglas fir							14.7	24	92f
Baker's yeast	Spruce	2.5	215	5	8%	5	32 FPU/g cellulase, 28 IU/g cellobiase	Not stated	72	60f	Alkasrawi et al. [25]
Baker's yeastg									72	92f
TMB 3000									48	89f
Baker's yeast	Spruce	3.0	215	5	5%	5	15 FPU/g cellulose, 23 CU/g cellobiase	Not stated	24	49f	Söderström et al. [35]
Baker's yeast	Spruce	3.0	210	5	12% WIS	5	15 FPU/g cellulose, 23 CU/g cellobiase	20.0 (graph)	72	37f	Hoyer et al. [38]
XR122N	Pine	3.3	215	5	10%	4	15 FPU/g cellulose, 60 CU cellobiase	28.7	48	98c	This study
XR122N	Pine	3.3	215	5	12%	4	15 FPU/g cellulose, 60 CU cellobiase	23.6	48	76c	This study

Abbreviations: FPU, filter paper unit; Inoc, inoculation; CU, cellobiase unit; temp, temperature; WIS, water-insoluble solids; WSF, water-soluble fraction.

^aSaccharomyces.

^bAll biomass was pretreated with SO2 in a single step and was not delignified before pretreatment or fermentation.

^cTheoretical yield based on cellulose and hemicellulose content derived from gravimetric and analytical analyses of pretreated material.

^dSteam explosion output was diluted to 15% w/w and filtered, and the pH altered to 6.0. Suspended solids not filtered out.

^eTheoretical yield was based on the content of glucose and mannose in the pretreated material.

^fTheoretical yield was based on the content of glucose and mannose in the liquid and of glucan in the solid material.

^gIn hydrolysate.