CESBIC--Critical Enzymes for Sustainable Biofuels from Cellulose

Lead Research Organisation: University of York
Department Name: Chemistry

Abstract

Sugar can be fermented to ethanol which can then be distilled to give ethanol good enough to be used as a fuel. This is bioethanol. Bioethanol is a 'sustainable fuel' meaning that its production and use has a significantly lower impact on the environment than oil or gas. It can make a major contribution to meeting our future energy demands. Why then don't we make more use of bioethanol? The answer lies in the sugar that is needed to make it in the first place. To be sustainable the sugars need to come primarily from plants. However, plants only produce relatively small amounts of sugar. Most of a plant's energy is tied up in a material called cellulose (essentially the material that gives a plant its structure), which-whilst it is made up of individual sugar units-cannot be efficiently broken down into its individual sugar units and therefore cannot be fermented. This means that the vast majority of a plant is useless in producing bioethanol.

Therefore, there has been a global search for a means of converting cellulose to sugar which is both efficient and simple. Such a solution now appears to be within our grasp. It turns out that fungi do this chemistry all of the time, by secreting enzymes which attack the cellulosic plant material they are degrading. Very recently these enzymes were isolated and studied. They were shown to be unprecedented in terms of their structure and biochemical function. It is clear that we need to study these enzymes in much more detail to make the best use of them.

This project aims to do exactly that, not only by studying the enzymes themselves, but also seeing how these can be then used directly in industry to make bioethanol. The project brings together some of the leading investigators from the UK, Denmark and France. We will take what is called a 'genomics to catalyst' approach, where the genomics allows to understand the full range of fungal enzymes that are used to degrade cellulose, and the 'catalyst' part is developing this knowledge to working industrial catalysts.

Technical Summary

Work described in this proposal aims to tackle head-on the single major limitation in sustainable bioethanol production. This limitation is their current inability to degrade effectively cellulose into glucose. As cellulose is, by far, the most abundant biopolymer synthesised in large quantities by all known plants (equivalent in energy to 20 times the global oil usage) its effective conversion to glucose and then into bioethanol via fermentation is of major importance. Indeed, all commentators on biofuels identify cellulose as the only really long-term sustainable source of bioethanol and that cellulose's recalcitrance to degradation is the limiting factor.

Of the more promising solutions that are being explored, the catalysed conversion of cellulose to glucose is the one that is attracting most commercial attention. In this context enzymatic degradation of cellulose by cellulases has been the focus of research for the last fifteen years, but it has been held back by a lack of understanding of how cellulose was initially attacked by oxidative enzymes, such that the cellulose is made accessible to more traditional cellulases. However, the field recently gained considerable momentum when the full structure of the fungal cellulose-degrading enzyme, GH61, was published in September 2011 gaining significant worldwide attention (10,000 downloads as of Jan 1 2012). This structure is vital as it now opens up the way for 1) understanding the key catalytic factors behind the enzymatic degradation of cellulose and 2) the development of biomimetic catalysts which carry out the same oxidative process. Given the importance of cellulosic bioethanol there is sure now to be a major worldwide effort to build on this discovery.

In this proposal we aim to take a genomics to catalyst approach to maximise the use of GH61s in the production of bioethanol.

Planned Impact

Biofuels hold the potential to make an essential contribution to UK and global energy demands. One of the keys to their development is the efficient conversion of biomass, particularly lignocellulosic biomass, into bioethanol. In this regard cellulose is by far the most important biomass source; it is very highly abundant (100 billion kilogrammes are produced globally every year), is present in all plants, and is the principal component of plants that can be grown densely on marginal land, e.g. switchgrass. The production of bioethanol from cellulose is, however, faced with a single critical issue. This issue is the chemical recalcitrance of cellulose. This recalcitrance severely limits its conversion to bioethanol and has, so far, prevented all attempts to generate significant amounts of bioethanol from sustainable plant sources. Indeed, reflecting the thoughts of all commentators on this issue, the International Energy Agency says that bioethanol will only play a major role in meeting sustainable energy demands if the key technological barrier of cellulose recalcitrance can be overcome (IEA, World Energy Outlook 2006).

The work described in this proposal seeks to address this key issue head-on. It builds on a recent and important breakthrough in the field, which is the full determination of the structure of a fungal enzyme called GH61. This class of enzymes is the long-sought-for 'missing link' in the conversion of cellulose to sugars by fungi. The action of the enzyme class is to oxidise cellulose directly thus making it tractable to other enzymes which can then convert it into soluble sugars and onto bioethanol. The structure of GH61 now points chemists towards the key chemical features of a synthetic catalyst which could be used itself to degrade cellulose. The way is now open, therefore, to generate cellulosic bioethanol sustainably. As such, the work in the proposal offers significant potential to the biofuel industry and to meeting the future energy demands of society.

Publications

10 25 50
 
Description We have shown how a class of enzymes known as LPMOs can greatly enhance the conversion of biomass through to biofuels.
Exploitation Route The cellulosic bioethanol industry can now develop these enzymes further to enhance the efficiencies of biorefineries.
Sectors Energy

 
Description The partner company on the grant (Novozymes) has taken information from the project to improve the performance of their enzyme products. Other companies and organisations have access to the new enzyme classifications via the publically-accessible CAZy database. Large biorefineries now make use of products from Novozymes which include LPMO enzymes that were investigated as part of this project.
First Year Of Impact 2014
Sector Energy
Impact Types Societal,Economic

 
Description Enzymes for biomass degradation 
Organisation National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS)
Department Centre National de la Recherche Scientifique Marseille
Country France 
Sector Academic/University 
PI Contribution We led the international team formed of these members. Our contribution was expertise in inorganic chemistry
Collaborator Contribution Genomics, plant biology, enzymology, spectroscopy
Impact Publications in leading journals
Start Year 2011
 
Description Enzymes for biomass degradation 
Organisation Novozymes
Country Denmark 
Sector Public 
PI Contribution We led the international team formed of these members. Our contribution was expertise in inorganic chemistry
Collaborator Contribution Genomics, plant biology, enzymology, spectroscopy
Impact Publications in leading journals
Start Year 2011
 
Description Enzymes for biomass degradation 
Organisation Stanford University
Department Department of Chemistry
Country United States 
Sector Academic/University 
PI Contribution We led the international team formed of these members. Our contribution was expertise in inorganic chemistry
Collaborator Contribution Genomics, plant biology, enzymology, spectroscopy
Impact Publications in leading journals
Start Year 2011
 
Description Enzymes for biomass degradation 
Organisation University of Cambridge
Department Department of Biochemistry
Country United Kingdom 
Sector Academic/University 
PI Contribution We led the international team formed of these members. Our contribution was expertise in inorganic chemistry
Collaborator Contribution Genomics, plant biology, enzymology, spectroscopy
Impact Publications in leading journals
Start Year 2011
 
Description Enzymes for biomass degradation 
Organisation University of Copenhagen
Country Denmark 
Sector Academic/University 
PI Contribution We led the international team formed of these members. Our contribution was expertise in inorganic chemistry
Collaborator Contribution Genomics, plant biology, enzymology, spectroscopy
Impact Publications in leading journals
Start Year 2011
 
Company Name Cambridge Glycoscience Ltd 
Description The company develops and markets carbohydrates from plant cell walls, for the food industry 
Year Established 2017 
Impact Too early to have achievements.
Website https://camglyco.com/
 
Description CESBIC - November 2015 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Research network discussions
Year(s) Of Engagement Activity 2015
 
Description Cambridge Science Festival, Cambridge UK - March 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other audiences
Results and Impact Particiapated in the Cambridge Science Festical at the Department of Chemistry.
Year(s) Of Engagement Activity 2017
 
Description LPMOs Symposium - November 2016 (Copenhagen) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Presented a talk at the LPMOs Symposium
Year(s) Of Engagement Activity 2016
 
Description Outreach at Botanic Gardens Festival of Plants 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact Outreach at Botanic Gardens Festival of Plants - Paul Dupree
Year(s) Of Engagement Activity 2016
 
Description Press release 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Press release and social media campaign to highlight biofuel potential of our recent discovery on enzymes.
Year(s) Of Engagement Activity 2016
URL http://www.nature.com/nchembio/journal/v12/n4/nchembio.2029/metrics
 
Description Sky News sugar science interview 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview about sugars in food for Sky TV news.
Year(s) Of Engagement Activity 2016
 
Description Tom Simmons - Food unwrapped 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Tom Simmons did a piece for the TV show 'food unwrapped' on Tuesday 16th Dec at the Lydney Park Estate in Gloucestershire. They were doing part of the show on cellulose in food and Tom was brought in as the cellulose expert.
Year(s) Of Engagement Activity 2015