INVESTIGADORES
AREA Maria cristina
congresos y reuniones científicas
Título:
Preliminary studies of cellulosic bioethanol production for simultaneous hydrolysis and fermentation testing
Autor/es:
ARISMENDY, A.M.; FELISSIA, F.; AREA, M. C.; CHAMORRO, M.
Lugar:
Concepción
Reunión:
Congreso; 3er Congreso Iberoamericano sobre Biorrefinerías (CIAB), 4to Congreso Latinoamericano sobre Biorrefinerías, y 2do Simposio Internacional sobre Materiales Lignocelulósicos; 2015
Institución organizadora:
CIADEB-RIADICYP-PROVALOR-BIOREN- Centro de Biotecnología UdeC- Unidad de Desarrollo Tecnológico (UDT)- VTT
Resumen:
To copewith the exhaustion of fossil fuels,it has become necessary to find validrenewable sources that do not compete with food production at affordable costsand alternatives. Cellulosic biomass can be chemically or enzymaticallyhydrolyzed, and the obtained sugars can be fermented with yeasts to produceethanol. The possibility of performing simultaneous hydrolysis and fermentationprevents enzymes inhibition, pollution risks and decreases production costs.The drawback is that the optimum temperature for the enzyme treatment is about50°C; where as the corresponding fermentation is close to 32°C. Rice husks(i.e. lignocellulosic waste of rice production), is an abundant resource in theNEA region of Argentina, and it is an excellent raw material for the bioethanolproduction because it has a high cellulose content. As preliminary tests forthe application of simultaneous enzymatic hydrolysis and fermentation to ricehusks, enzymatic hydrolysis on Whatman filter paper N°1 at temperatures below theoptimum (32°C), and subsequent fermentation with four different yeast,Saccharomyces cerevisiae, Candida tropycalis, Candida guilliermondii and Candidakéfir, were performed at the same temperature. Yeast selection was based uponspecific criteria. Candida kéfir can with stand temperatures up to 37°C, so itwas taken as afeasible alternative for the simultaneous process at hightemperatures [1]. Candidas works at 32°C, but they also have affinity for5-carbon sugars such as xylose, present in small amounts if the material hasbeen pretreated with acid to remove hemicelluloses. The filter paper wascharacterized through moisture and ash amounts. The enzymatic hydrolysis withcelullases of Trichoderma reseei and celobiasses of Aspergillus níger wasaccomplished during 72 hours at 32ºC in a rotary shaker.The amount of glucoseobtained by the hydrolysis was determinate by High Performance LiquidChromatography (HPLC) with refractive index (IR) detector.In the hydrolysis at32°C the cellulose conversion to glucose was 81%. The supernatants of thehydrolysis were supplemented with nutrients, and were subjected to subsequentfermentation with the four yeasts listed above; stirring for 24 hours at 32 ° C.The ethanol generated in each case was determined by HPLC. Ethanol yieldsobtained were 66.2% for Saccharomyces cerevisiae, 61.47% for Candida tropycalis,45% for Candida kéfyr, and 32.42% for Candida guilliermondii. Results showedthat all yeasts generated ethanol, even when the fermentation time was only 24hours. Based on these encouraging results (hydrolysis and fermentation at 32°Cfor 24 hours), the simultaneous processing ofrice hulks was accomplished inthese conditions, obtaining up to 70% of ethanol when using Saccharomyces cerevisiae.