Bioethanol production from sugarcane bagasse hemicellulosic hydrolyzate by Scheffersomyces (Pichia) stipitis NRRL Y-7124 and Candida shehatae UFMG HM 52.2 yeasts aiming at application in bioprocesses with electromagnetic field

Author(s)

Kelly Johana Dussan Medina

• Document type: Doctoral Thesis
• Press: Lorena.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de Lorena (EEL/ASDI)
• Defense date: 2013-06-06

Examining board members

Silvio Silverio da Silva; Mário Antonio Alves da Cunha; Angela Maria Moraes; Rosemeire Cristina Linhari Rodrigues Pietro; Júlio César dos Santos

• Advisor: Silvio Silverio da Silva; Victor Haber Perez

Abstract

Currently the use of biomass is of huge interest into the second generation bioethanol process. Into this field, fermentation is a key process with numerous opportunities for innovation. Electromagnetic fields bioreactors stand for a new and promising research area for the yield and/or productivity improvement of fermentation process. This study focused on the utilization of hemicellulose hydrolysate from sugarcane bagasse for ethanol production by Scheffersomyces stipitis NRRL Y-7124 and Candida shehatae UFMG HM 52.2 strains intended to be applied in the electromagnetic-based bioprocesses. A 23 full factorial Central Composite Design (CCD), including three replications at the center point was applied to evaluate the effect of initial pH, agitation and air-flow rate on sugars to ethanol conversion for both strains. The experiments were carried out using stirred tank batch fermentor with medium supplemented with yeast extract and containing hemicellulose hydrolysate previously detoxified. S. stipitis showed the best ethanol production operating conditions obtained at 100 rpm, 0.7 vvm and initial pH 6.50 with kLainicial of 3 h-1 obtaining YP/S of 0.16 g/g and QP of 0.10 g L-1 h-1. For C. shehatae, the best conditions of 100 rpm, 0.1 vvm and pHinitial of 6.50 with kLainicial of 0.2 h-1 obtained YP/S of 0.44 g/g and QP of 0.25 g L-1 h-1. The results showed that yield and ethanol productivity for C. shehatae strain was higher comparing to S. stipitis. Subsequently, the influence of electromagnetic field configuration in the fermentation process of sugarcane bagasse hemicellulosic hydrolyzate was evaluated using immobilized C. shehatae in a polymer with magnetic properties. The application of electromagnetic field configuration (axial and transversal) favored the ethanol production, observing at increase of 47 % in ethanol production (axial configuration) compared to the control experiment (no electromagnetic field). The present study demonstrated that C. shehatae yeast shows high fermentative potential for sugarcane hemicellulose hydrolyzate when compared to S. stipitis strain, and that electromagnetic fields are a promising technology tool to be used into the bioethanol process. (AU)

• FAPESP's process: 11/01226-7 - Comparative analysis of bioethanol production from sugarcane bagasse hemicellulosic hydrolysate by Pichia stipitis NRRL Y-7124 and Candida shehatae UFMG 52.2 HM yeasts aiming its application in bioprocesses with electromagnetic field
• Grantee: Kelly Johana Dussán Medina
• Support Opportunities: Scholarships in Brazil - Doctorate