Fermentation of hexoses and pentoses from hydrolyzed soybean hull into ethanol and xylitol by Candida guilliermondii BL 13

F Da Cunha-Pereira,M A Záchia Ayub,A P Dillon,R Rech,L R Hickert

doi:10.1590/0104-6632.20170344s20160005

F Da Cunha-Pereira, M A Záchia Ayub + Show 3 more

Open Access

https://doi.org/10.1590/0104-6632.20170344s20160005

Copy DOI

Abstract

Abstract This work investigated the ability of a recently isolated strain of Candida guilliermondii to convert hexoses and pentoses obtained from acid-enzymatic soybean hull hydrolysates into ethanol and, in smaller amounts, into xylitol. Operational conditions and media formulation were optimized concerning ethanol production using experimental designs (Plackett-Burman and Central Composite Design). Results showed that C. guilliermondii BL 13 was capable of growing in non-supplemented, non-detoxified biomass hydrolysates, and the best culture conditions were determined to be 28 °C, pH 5.0, and 109 CFU mL-1 of inoculum size. Ethanol productivity reached 1.4 g L-1 h-1, and maximal yields of 0.41 g g-1 were obtained, representing 80.4 % of the expected theoretical yields, whereas small amounts of xylitol were also produced. These results suggest that C. guilliermondii BL13 is a potentially useful yeast strain to be applied in second-generation ethanol production from lignocellulosic biomass based on its natural capacity to metabolize C-5 and C-6 sugars.

Highlights

Lignocellulosic biomass materials represent an abundant and renewable source of carbohydrates that can be used to produce chemical specialties and biofuels of high-added value through biochemical processes, which is a promising alternative to oil-based products (Martínez, 2012)
Similar results were observed in the fermentation of brewers spent grain hydrolysate by Candida guilliermondii FTI 20037 aiming at conversion of xylose to xylitol (Mussatto and Roberto, 2008)
The addition of these nutrients could be eliminated for the subsequent experiments, at the same time showing that the use of soybean hull hydrolysate is an interesting substrate for fermentation processes because it does not require expensive supplementations

Summary

Introduction

Lignocellulosic biomass materials represent an abundant and renewable source of carbohydrates that can be used to produce chemical specialties and biofuels of high-added value through biochemical processes, which is a promising alternative to oil-based products (Martínez, 2012). The production of ethanol from sugary substrates, such as sugarcane in Brazil and maize starch in the USA, is economically sound and has been the main technology to obtain this biofuel. There is a large amount of lignocellulosic biomass, consisting of cellulose, hemicellulose, and lignin, which could be used to obtain second-generation ethanol (Kuhad et al, 2011). In order to achieve these objectives, compatible costs of biomass preparation (i.e., the liberation of sugars from the lignocellulosic matrix), and the use of yeast strains capable of converting both hexoses and pentoses into ethanol, are necessary.

Methods

Results

Conclusion