Bioprocessing of rice husk into monosaccharides and the fermentative production of bioethanol and lactate

Authors: MONTIPÓ, SHEILA - Universidade De Caxias Do Sul; BALLESTEROS, IGNACIO - Research Centre For Energy, Environment And Technology; FONTANA, ROSELEI - Universidade De Caxias Do Sul; Liu, Siqing; BALLESTEROS, MERCEDES - Research Centre For Energy, Environment And Technology; MARTINS, AYRTON - Universidade Federal De Santa Maria; CAMASSOLA, MARLI - Universidade De Caxias Do Sul

Submitted to: Cellulose
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2019
Publication Date: 6/26/2019
Citation: Montipó, S., Ballesteros, I., Fontana, R.C., Liu, S., Ballesteros, M., Martins, A.F., Camassola, M. 2019. Bioprocessing of rice husk into monosaccharides and the fermentative production of bioethanol and lactate. Cellulose. 26:7309–7322. https://doi.org/10.1007/s10570-019-02571-1.
DOI: https://doi.org/10.1007/s10570-019-02571-1

Interpretive Summary: A green biorefinery scheme was designed to convert low valued agricultural waste rice husk to biofuel ethanol and bioproduct lactic acid via two separate but parallel biochemical fermentation routes. The steam pretreated rice husk solids were separated from the liquor. Hydrolysis of the solids with enzymatic cocktail resulted in high sugars which were fermented to ethanol via yeast SSF fermentation. The liquor portion of the pretreated rice husk was used for lactic acid production by Lactobacillus buchneri. This study explored a green platform and the process used here will be valuable for cost effective fuel and chemical productions.

Technical Abstract: Rice husk, a residue from agro-industrial processing, is one of the most abundant lignocellulosic feedstocks in the South of Brazil. In this study, the uncatalyzed steam-exploded rice husk slurry was separated in liquid and solid fractions. The liquor was hydrolyzed by using an enzymatic complex produced from Penicillium echinulatum S1M29 strain, then followed by lactic acid production by using Lactobacillus buchneri NRRL B-30929 which can efficiently utilize a blend of xylose and glucose presented in the liquor. The water insoluble solids were subjected to simultaneous saccharification and fermentation process using high solid loading combined with distinct doses of commercial enzymes, producing ethanol via Saccharomyces cerevisiae CAT-1. In total, 12.69g L-1 of lactic acid and 19.17g L-1 of ethanol were produced, demonstrating that this abundant low valued renewable feedstock can be explored through a cleaner and greener environmentally friendlier production.