Converting crop biomass into energy and bio-products is a promising approach to curtailing greenhouse gas emissions and providing a sustainable alternative to petrochemical products. MaxBio (Maximizing Conversion Yields in Biorefining) focuses on under-utilized cereal straw and its conversion into biofuel and chemicals.

Using cereal straw as a feedstock for biorefining to produce fuels and chemicals offers significant advantages. As well as generating extra income for growers from straw sales, it offsets the high carbon cost of agricultural inputs such as fertiliser and energy used for grain production. Using renewable materials such as straw in place of fossil fuels can ultimately reduce carbon dioxide emissions and mitigate climate change.

Straw composition and its digestibility are mainly determined by the plant’s genetics which greatly influences the ease with straw biomass can be broken down and converted into useful products. In fact, these traits have never been the subject of breeding selections, which points to a great prospect for straw quality improvement. Similarly, the pre-treatments and enzymes used to release sugar and other chemicals from straw, could be greatly improved in efficiency and reduced in cost, while the microbes that ferment those sugars into chemicals could be manipulated to provide greater yields of a wider variety of useful products.

MaxBio takes a holistic approach to increasing yields across the whole process from biomass into biofuel and bio-chemicals by, exploiting the latest technologies and innovations to target industrially relevant products. The project translates and integrates our recent research advances in crop genetics, genomics and cell wall biology (at the University of Dundee & The James Hutton Institute), with novel pre-treatment methods and enzyme cocktails (at the University of York), and superior microbes engineered by synthetic biology for biofuel and chemical production (at the University of Nottingham). Several companies are advising the project to ensure that we remain aware of the broader agricultural and industrial context, including James Hutton Ltd, CHAIN Biotech, and Corbion.

Maximising sugar yield from cereal straw: We have discovered considerable diversity for straw digestibility among 961 barley cultivars and subsequently revealed the genomic regions underpinning these variations. To understand the relationship between straw digestibility and plant vigour and health, we also studied a comprehensive list of straw characteristics and agronomical traits. Combining this knowledge we can now embark upon improving straw digestibility in both barley and wheat without altering the strength and resilience of modern high-yielding varieties.

Improving pre-treatments and enzyme hydrolysis: Pre-treatment of straw removes cell wall barriers and increases accessibility to sugar but overly harsh pre-treatments risk losing sugars in the process and releasing inhibitors, while more gentle methods may not make sugars fully accessible. We are optimising pre-treatments for barley straw to maximize sugar release while minimizing inhibitors. The pre-treated straw will be digested by enzymes to release sugars for further conversion. Our partners at the University of York have generated a library of novel lignocellulose enzymes from marine organisms and a fungus. MaxBio will exploit combinations of these enzymes on improved straw to understand functionality and increase sugar yields for fermentation.

Creating novel fermentation microbes: Efficiency of microbial strains greatly impacts fermentation. Technologies developed at University of Nottingham-SBRC in combination with robotic platforms can rapidly create engineered microbial strains. These patented technologies modify strains to produce high yield of alkanes, 3HP and 3HB, succinate, lactate, IPA, ethanol and butanol.

In contrast to other research where the distinct production steps are optimised in isolation by plant biologists, process engineers, biochemists or microbiologists, MaxBio’s novel integrated approach could radically improve the cost and efficiency of producing a range of renewable fuels and biochemicals to replace oil-derived products in a sustainable bio-based economy.

For further information on this project please contact Claire Halpin (c.halpin@dundee.ac.uk) or Morven Pearson (m.pearson@dundee.ac.uk) from the James Hutton Institute / University of Dundee.