Evaluation of the tolerance of acetic acid and 2-furaldehyde on the growth of Pichia stipitis and its respiratory deficient

Abstract

The use of lignocellulosic residues for ethanol production is limited by toxic compounds in fermenting yeasts present in diluted acid hydrolysates like acetic acid and 2-furaldehyde. The respiratory deficient phenotype gives the cell the ability to resist several toxic compounds. So the aim of this work was to evaluate the tolerance to toxic compounds present in lignocellulosic hydrolysates like acetic acid and 2-furaldehyde in Pichia stipitis and its respiratory deficient strains. The respiratory deficient phenotype was induced by exposure to chemical agents such as acriflavine, acrylamide and rhodamine; 23 strains were obtained. The selection criterion was based on increasing specific ethanol yield (g ethanol g -1 biomass) with acetic acid and furaldehyde tolerance. The screening showed that P. stipitis NRRL Y-7124 ACL 2-1RD (lacking cytochrome c), obtained using acrylamide, presented the highest specific ethanol production rate (1.82 g g -1 h -1). Meanwhile, the ACF8-3RD strain showed the highest acetic acid tolerance (7.80 g L -1) and the RHO2-3RD strain was able to tolerate up to 1.5 g L -1 2-furaldehyde with a growth and ethanol production inhibition of 23 and 22 %, respectively. The use of respiratory deficient yeast phenotype is a strategy for ethanol production improvement in a medium with toxic compounds such as hydrolysed sugarcane bagasse amongst others.

Ethanol production by Pichia stipitis immobilized on sugarcane bagasse

“…The use of respiratory deficient (RD) phenotype in yeasts could be interesting in immobilized cell systems as oxygen availability is less than in free cells systems; the use of this phenotype could therefore be an option in order to increase ethanol production. On the other hand, RD Pichia stipitis ACL 2-1 becomes interesting because of its ability to produce ethanol from glucose and xylose, although its acetic acid and 2-furaldehyde tolerance were not the highest compared to other Pichia stipitis RD strains [16]. Therefore, the aim of this work was to evaluate ethanol production by Pichia stipitis immobilized on sugarcane bagasse pre-treated with diluted sulphuric acid.…”

“…The RD P. stipitis ACL 2-1 employed in this study was obtained previously by acrylamide exposure [16].…”

Estudo da fermentação de hidrolisado lignocelulósico de bagaço de cana -de-açúcar pela linhagem Spathaspora passalidarum UFMG HMD 14.1

“…Os resultados obtidos para tolerância ao furfural estão de acordo com os reportados em literatura, onde 1,5g/L de furfural foi responsável pela inibição total do crescimento celular da levedura S. stipitis Y-7124, em meio semissintético contendo glicose como fonte de carbono e pH 5,5 (ORTIZ-MUÑIZ et al, 2014).…”