Mining compost communities for lignocellulolytic enzymes

Second generation biofuels, which use feedstocks of the inedible component of plant cell walls: lignocellulose, for the production of liquid transportation fuels, have been publicised as a clean and renewable alternative for petroleum. However, current methods for the breakdown of lignocellulose, required for fermentation of agricultural waste into biofuel, are not economically feasible for an industrial scale. Our work uses compost microbial communities, which have evolved to breakdown the extensively crossed linked polymers of cellulose, hemicellulose and lignin that make up lignocellulose, as a source of novel enzymes. These can then be applied to the biomass as an efficient biological pre-treatment, with a low energy requirement. Fungal and bacterial members of a community enriched for growth on wheat straw have been identified and assayed for degradation activity against the components of lignocellulose. A soft rot fungus identified as Graphium sp. appeared to consistently dominate the microbial community across an eight week timescale and its growth has been optimised and characterised on lignocellulose derived substrates. Proteomic methods used to identify enzymes responsible for the deconstruction of these polymers, along with metatranscriptomics, to compare transcriptional response to lignocellulosic substrates, will also be applied to isolates. In addition metagenomics, metatranscriptomics and metaproteomics will be used to examine the uncultivable members of the compost community. By using a combination of classical microbiology with meta-techniques we aim to gain an understanding of both degradation methods and enzymes used by individual members of microbial community and those of the dynamic community in which they are found.