Selection and genetic improvement of yeasts for the conversion of lignocellulose into second generation bioethanol
Year: 2013
Type: article
Abstract: Bioethanol produced from lignocellulosic biomass represents a promising alternative among biofuels. To date a cost-effective method for the industrial production of bioethanol from vegetal biomass has not been developed. One of the most attractive strategies is the construction of a CBP (Consolidated BioProcessing) microbe able both to hydrolyze the complex polymers of lignocellulosic biomass and to convert these into ethanol. In this context, the present study focused on the development of an industrial CBP microbe for the conversion of cellobiose into ethanol. To this purpose, it was necessary to define a new screening method for the selection of a yeast strain, suitable for the industrial bioethanol production having high fermentative abilities and considerable tolerance to inhibitors commonly present in lignocellulosic hydrolysates. The selection started from a collection of oenological yeasts. These strains, although showing interesting fermentative abilities, did not exhibit a good tolerance to inhibitors such as furfural, acetic acid, formic acid and lactic acid. Therefore, a new isolation programme was necessarily conducted in order to select efficient fermenting yeast strains able to tolerate high concentrations of inhibitory compounds. The isolation procedure, conducted in the presence of an inhibitors cocktail, allowed to obtain a wide collection of yeasts with interesting features for their future applications in the field of second generation bioethanol. Among them, few S. cerevisiae yeasts exhibited remarkable fermenting vigour at high temperature and promising inhibitors tolerance. In particular, S. cerevisiae T2 was selected as host for the development of a recombinant strain able to produce the BglI β-glucosidase of Saccharomycopsis fibuligera, one of the most efficient cellobiose hydrolyzing yeast species. For the first time, in this study, an industrial yeast strain secreting β-glucosidase BglI was described. However, the hydrolytic activity of the recombinant strain must be necessarily increased in order to produce an efficient cellulolytic CBP microbe. On the basis of the preliminary results obtained, this multi-disciplinary work represents a first step towards the development of microbes for the single-step conversion of lignocellulosic biomass to ethanol.
Author: Alberto Trento
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W74135688