Fig. 1

Schematic illustration of the pre-adaptation strategy and SSF. Wheat straw was pre-treated by acid-catalysed steam explosion and the biomass slurry was separated by filtration into a liquid fraction (a) and a water-insoluble solids (WIS) fraction (d). Unadapted (b) and pre-adapted (c) seed cultures were inoculated in the SSF bioreactor (e, f), respectively. Whereas only the liquid fraction (hydrolysate) was used for seed cultivations, both hydrolysate and WIS (brown fibres in e and f) were added to the SSF