How can scientists devise new ways to make the chemicals used to manufacture the materials, plastics, solvents and drugs that industry and society need every day from plant biomass instead of oil? Lots of new technology will be needed in the next 20-30 years to discover new biocatalysts and chemical catalysts that could be used to convert cellulose, hemicellulose, lignin and starch into useful chemicals.
Aromatic Chemicals from Lignin
Lignin is an aromatic polymer found in plant lignocellulose that is made up of aryl-C3 units linked together by a variety of C-C and C-O ether linkages. Lignin is a potential source for making renewable aromatic chemicals from plant biomass, but it is very hard to break down.
In a project funded by the BBSRC Integrated Biorefining Research and Technology Club, Professor Tim Bugg has developed new strategies for breaking down lignin into renewable chemicals. As well as discovering a new bacterial lignin peroxidase enzyme DypB, his group has used a novel assay for lignin breakdown to discover a group of new lignin-degrading bacteria, including strains of Microbacterium and Ochrobactrum that have also been seen in termite guts, and a thermotolerant strain of Sphingobacterium sp. T2 that shows high lignin degradation activity.
In collaboration with Professor Lindsay Eltis (University of British Columbia, Canada), Professor Bugg's group are developing pathway engineering strategies to utilise bacterial lignin degradation pathways to produce higher yields of aromatic chemicals. They recently discovered a gene deletion strain of Rhodococcus jostii that produces yields of up to 96 mg/L of vanillin, a high value aromatic chemical used in the food and flavour industry.
“Development of novel assays for lignin degradation: comparative analysis of bacterial and fungal lignin degraders” M. Ahmad, C.R. Taylor, D. Pink, K. Burton, D. Eastwood, G.D. Bending and T.D.H. Bugg, Molecular Biosystems, 6, 815-821 (2010)
“Isolation of bacterial strains able to metabolise lignin from screening of environmental samples” C.R. Taylor, E.M. Hardiman, M. Ahmad, P.D. Sainsbury, P.R. Norris, and T.D.H. Bugg, J. Appl. Microbiol., 113, 521-530 (2012)
“The emerging role for bacteria in lignin degradation and bio-product formation” T.D.H. Bugg, M. Ahmad, E.M. Hardiman, and R. Singh, Curr. Opin. Biotech., 22, 394-400 (2011)