Fig. 5

Relative impact of five recalcitrance levers on total carbohydrate solubilization. The increase in total carbohydrate solubilization for each lever in bold is calculated with other levers as indicated. For example, the impact of plant natural variants (Populus trichocarpa GW9947 vs BESC97) is calculated using data obtained with both C. thermocellum and fungal cellulase SSF without augmentation, the impact of augmentation is calculated using C. thermocellum for COMT+ and COMT− switchgrass lines as well GW9947 vs BESC97 Populus lines. P. trichocarpa GW9947 has a mutation in the lignin pathway resulting in a lower lignin content; BESC97 is a control without this mutation. Transgenic switchgrass lines COMT and MYB4 have modifications in the lignin pathway, and GAUT4 has a modification in the pectin pathway. Respective nontransgenic controls are included for tests involving the three transgenic switchgrass lines. The recalcitrance lever ‘Augmentation’ includes cotreatment and CELF (Cosolvent-enhanced lignocellulosic fractionation) as well as unaugmented plant controls. Data are calculated from duplicate fermentation runs with equal initial glucan loading. For solubilization data see Additional file 1: Tables S1 A, B, C. Solubilization results are after 120 h of incubation. An asterisk (*) in the tabularized section denotes statistically significant, for full details on the statistical analysis see Additional file 3: Tables and Figures S6–S10