Batch and Fed-Batch Simultaneous saccharification and fermentation of Cashew Apple Bagasse by Kluyveromyces marxianus ATCC36907

The cashew apple bagasse (CAB) was subjected to pretreatment with alkaline hydrogen peroxide (AHP) to provide pretreated biomass with increased cellulose content relative to untreated materials and to enhance cellulase accessibility with extraction of lignin. The conditions for pretreatment were as follows: 4.3% (v/v) peroxide hydrogen (pH 11.5) at 35 ºC, 150 rpm, 5% (w/v) raw material for 6 hours and then used in this study of the simultaneous saccharification and fermentation (SSF) with thermotolerant yeast strain Kluyveromyces marxianus ATCC36907. Initially batch SSF processes were studied to evaluate the effect of the temperature and bagasse loading. After, the fed-batch SSF processes were conducted to evaluate the effect of different feeding enzyme loading and bagasse loading with addition at 12 hours of the process. The maximum ethanol concentration obtained in the batch SSF was 12 g/L at 48 h cultivation, using 3.3 g_cellulose/100 mL at 45 °C and 150 rpm, with yield and productivity of 0.36 g_ethanol/g_cellulose and 0.28 g.L^-1.h^-1, respectively. However, SSF processes showed the difficulty of using the slurry for ethanol production under higher CAB loading. Fed-batch SSF processes resulted in better configuration, reaching the highest ethanol concentration (22.5 g/L) with an initial CAB content of 4% (w/v) and 6% (w/v) of substrate addition at 12 h, which meant 50% more ethanol when compared with batch SSF. Based on these results, the cashew apple bagasse pretreated presents a promising substrate for the ethanol production by batch and fed-batch simultaneous saccharification and fermentation using K. marxianus ATCC 36907.