In our previous work, the ability of laccase enzymes to improve the fermentation performance of the
thermotolerant yeast Kluyveromyces marxianus CECT 10875 on steam-exploded wheat straw slurry was
demonstrated. As a continuation of this study, the present research evaluates different aspects, including
pretreatment conditions, process configurations and substrate loadings, with the aim to proceed towards
the use of K. marxianus and laccases for second generation ethanol production. For it, two wheat straw
slurries resulting from different steam explosion pretreatment conditions (200 ◦C, 2.5 min and 220 ◦C,
2.5 min) were employed at various substrate loadings [5–14% (w/v)] under two process configurations:
SSF (simultaneous saccharification and fermentation) and PSSF (presaccharification and simultaneous
saccharification and fermentation). The better performance of K. marxianus was observed on the slurry
produced at softer conditions. Its lower inhibitors content allowed to increase the total solids loading
up to 10% (w/v) in both process configurations, reaching higher ethanol concentrations (12 g/L). Moreover,
laccase detoxification improved these results, particularly in SSF processes, increasing the substrate
loading up to 12% (w/v) and, consequently, obtaining the highest ethanol concentration (16.7 g/L).