Metagenomics and metaproteomics of lignocellulose transformation by enriched microbiomes from cow rumen and termite gut

Lignocellulose (LC) valorisation into energy and synthons is one of main concerns to overcome fossil energy dependence. In the environment, the recycling of LC is realised by complex microbial communities that have evolved to select the more efficient enzyme mixtures which, by a synergistic action, enable the bioconversion of complex LC. Cow rumen and termite gut microbiomes are natural ecosystems known for their LC degradation capacity that can be exploited in biorefinery processes. Nevertheless, despite the interest of such ecosystems little information exists on the dynamics of microorganisms and proteins involved on LC deconstruction in bioconversion processes.

Our aim was to produce microbial consortia displaying high lignocellulolytic potential and high capacity to produce carboxylates using termite gut and cow rumen microbiomes. We also wanted to correlate the functional diversity assessed by meta-genomic/-proteomic approaches of these consortia with their enzyme activity and LC degradation profiles. To this aim, we studied the lignocellulolytic capacities of four species of tropical termites (T. hospes, M. parvus, N. lujae and N. ephratae) using wheat straw as sole carbon source. N. ephratae showed high LC degradation potential. Furthermore, N. ephratae and cow rumen microbiomes were selected to enrich the most active lignocellulolytic species by sequencing batch reactor process. Sequencing of 16S rRNA gene and metaproteomics of the enriched consortia showed important differences in the functional species and enzymes present in these ecosystems. In this presentation, insights in enzymes activities, proteins and diversity will be discussed, providing better understanding of LC deconstruction by microbial consortia.