Due to the negative effects associated to fossil fuel use more research needs to be done on renewable energy sources. Biofuels synthesized from lignocellulosic biomass represent one of the alternatives to fossil fuels. Enzymes that catalyze the degradation of lignocellulosic polymers are crucial for processing of lignocellulosic biomass to bioenergy. Glycoside hydrolases represent the most important group of these enzymes. New enzymes from the environment can be obtained without isolating new bacteria by using the metagenomic approach. This approach is based on the analysis of the whole DNA isolated from an environmental sample, bioinformatic analysis of the genes and/or expression of target genes in a heterologous expression system. In this work we analysed 5 ORFs encoding putative enzymes involved in lignocellulose degradation on compost metagenome, which we expressed in various Escherichia coli strains. Among these putative enzymes, we successfully expressed a 40 kDa xylanase from glycoside hydrolase family 10. In addition, we also tested biotechnological potential of the target enzymes for valorization of brewer's spent grain. The activity of crude as well as isolated enzyme on brewer’s spent grain was approximately two times higher at 25 °C then at 37 °C. Finally, we conducted a biomethane potential test (BMP), and compared methane production from brewer's spent grain that was pre-processed with Y006 and methane production from unprocessed brewer's spent grain.
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