Table reports xylose conversion degree xyl butanol yield YB

The concentration of MLN8054 inhibitors in 48-h substrate hydrolysates was determined by HPLC for both unwashed and water-washed substrates as well as for Avicel® and Celuflock®, which were used as unlignified substrate controls (Table 4). Furfural and 5-hydroxymethylfurfural (HMF) were only detectable in the hydrolysates of unwashed substrates that were produced under higher pretreatment severities but, even so, their concentration was always below inhibitory conditions (less than 0.1 g/L). (Ewanick and Bura, 2011) also reported non-inhibitory concentrations of HMF and furfural in the steam explosion liquid streams derived from switchgrass and sugarcane bagasse. Since unwashed substrates were not as good for hydrolysis as water-washed substrates, it seems that inhibition came from the water-soluble carbohydrate moiety (mostly oligomers) of these steam exploded materials and this would be consistent with the findings of (Qing et al., 2010), who showed that the presence of xylooligomers dramatically decreases the conversion rates and yields of cellulose hydrolysis.