A comparative study on bioethanol production from rice straw and banana pseudostem through simultaneous saccharification and fermentation using Kluyveromyces marxianus

Abstract

To improve the efficiency of second-generation bioethanol production, simultaneous Saccharification and Fermentation (SSF) of top agricultural wastes in the Philippines such as rice straw and banana pseudostem was conducted using commercial enzymes and the thermotolerant yeast Kluyveromyces marxianus. Residues were initially subjected to chemical treatment prior to SSF. A constant inoculum loading of 10% vv -1 was introduced during SSF, and mixed with a nutrient supplemented solution. Aside from the enzyme loading, the effect of reaction temperature and reaction time on ethanol concentration was assessed. Among the tested parameters, only reaction time had a significant effect on the bioethanol concentration from both biomasses. For a pre-treated rice straw with 70.93% ww -1 holocellulose, highest ethanol concentration obtained was 6.30+0.44 gL -1 at 45°C, reaction time of 48 h and with enzyme loading of 30 FPUg -1. On the other hand, 5.35+0.29 gL -1 ethanol was achieved from SSF of banana pseudostem with 67.75% ww -1 holocellulose, also at 35°C, at a lower reaction time of 24 h and same enzyme loading of 30 FPUg -1. This study also proves that the thermotolerant K. marxianus was capable of producing bioethanol from lignocellulosics through SSF, thereby considering it as a potential alternative to Saccharomyces cerevisiae for bioethanol production.