Xylose fermentation to ethanol by new Galactomyces geotrichum and Candida akabanensis strains

Raquel V Valinhas; Lílian A Pantoja; Ana Carolina F Maia; Maria Gabriela C P Miguel; Ana Paula F C Vanzela; David L Nelson; Alexandre S Santos

doi:10.7717/peerj.4673

Xylose fermentation to ethanol by new Galactomyces geotrichum and Candida akabanensis strains

PeerJ. 2018 Apr 27:6:e4673. doi: 10.7717/peerj.4673. eCollection 2018.

Authors

Raquel V Valinhas¹, Lílian A Pantoja², Ana Carolina F Maia³, Maria Gabriela C P Miguel⁴, Ana Paula F C Vanzela³, David L Nelson¹, Alexandre S Santos⁵

Affiliations

¹ Graduate Program of Biofuels, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, Minas Gerais, Brazil.
² Science and Technology Institute, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, Minas Gerais, Brazil.
³ Department of Pharmacy, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, Minas Gerais, Brazil.
⁴ Department of Biology, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil.
⁵ Department of Basic Sciences, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, Minas Gerais, Brazil.

Abstract

The conversion of pentoses into ethanol remains a challenge and could increase the supply of second-generation biofuels. This study sought to isolate naturally occurring yeasts from plant biomass and determine their capabilities for transforming xylose into ethanol. Three yeast strains with the ability to ferment xylose were isolated from pepper, tomato and sugarcane bagasse. The strains selected were characterized by morphological and auxanographic assays, and they were identified by homology analysis of 5.8 S and 26 S ribosomal RNA gene sequences. The identities of two lineages of microrganism were associated with Galactomyces geotrichum, and the other was associated with Candida akabanensis. Fermentative processes were conducted with liquid media containing only xylose as the carbon source. Y_P/S values for the production of ethanol ranging between 0.29 and 0.35 g g^-1 were observed under non-optimized conditions.

Keywords: Alcoholic fermentation; Bioethanol; Hemicellulose; Pentoses; Yeast.

Grants and funding

This work was supported by Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq/Brazil). DL Nelson was the recipient of a PVNS fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior (CAPES/Brazil). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.