Mining of the microbial biodiversity for the identification of new enzymes and strains for CBP

Informations

Funding country

France

Acronym

BIOMINES

URL

-

Start date

6/1/2012

End date

6/1/2016

Budget

786,175 EUR

Fundings

Abstract

There are worldwide efforts to enhance sustainable development, including the growing use of biofuels to replace fossil energy-based fuels. Bioethanol represents a major part of biofuels, but currently used resources, sugar and starch-based food crops, will soon be limiting for the increasing demand. The development of cost-effective second generation biofuels, produced from lignocellulosic biomass is a promising alternative which can lead to substantial reductions of greenhouse gas emissions and avoid competition of land use for food production. Present process configurations and especially the production of cellulolytic enzymes are, however, too expensive to constitute viable solutions. The Consolidated Bioprocessing scheme employing a single organism for both hydrolysis of lignocellulosic biomass and fermentation of liberated sugars, could allow important cost savings. Economic production requires, in addition, that all constituents of lignocellulosic biomass and especially pentose sugars are utilized. Today, no micro-organism able to use all sugar components and to efficiently catalyse the two transformation steps is available. In the present research project, we therefore propose to isolate micro-organisms and (hemi)cellulolytic enzymes from specific adapted environments to constitute the base for the development of a future CBP biocatalyst. To maximize the chance of discovering relevant micro-organisms, specific enrichment cultures on lignocellulosic biomass will be set up, inoculated with microflorae from plant polymer degrading environments. Selected substrates and well defined conditions will be employed to isolate the best adapted strains likely to lead to well performing biocatalysts under industrial conditions. In addition, a culture collection including thermophiles and hyper-thermophiles will be screened for strains with (hemi)cellulolytic activity. The capacity of strains to produce ethanol and other alcohols will also be tested. As the majority of strains from natural systems cannot be cultivated, the enrichment cultures will also serve as a source for mining the uncultivable part of the (hemi)cellulose degrading microbial communities, using a metagenomics approach. By this way, an important pool of enzymes of much higher diversity will be created. To ensure the highest success rates for the isolation of relevant genes, a characterization by TGGE analyses and 16S sequencing of the enrichment cultures will help choosing the best samples for extraction of nucleic acids. This metagenomic DNA will be mined by direct pyrosequencing and by functional screening for cellulolytic and hemicellulolytic enzymes. Bioinformatic analysis will identify Carbohydrate Active enZymes (CAZymes) and guide the selection of enzymes to be further characterized. Expression in the model strain Clostridium cellulolyticum will allow a first evaluation of the genes for their suitability to be integrated in a future CBP micro-organism.