Potential of Selected Rumen Bacteria for Cellulose and Hemicellulose Degradation

Herbivorous animals harbour potent cellulolytic and hemicellulolytic microorganisms that supply the host with nutrients acquired from degradation of ingested plant material. In addition to protozoa and fungi, rumen bacteria contribute a considerable part in the breakdown of recalcitrant (hemi)cellulosic biomass. The present review is focused on the enzymatic systems of three representative fibrolytic rumen bacteria, namely Ruminococcus flavefaciens, Prevotella bryantii and Pseudobutyrivibrio xylanivorans. R. flavefaciens is known for one of the most elaborated cellulosome architectures and might represent a promising candidate for the construction of designer cellulosomes. On the other hand, Prevotella bryantii and Pseudobutyrivibrio xylanivorans produce multiple free, but highly efficient xylanases. In addition, P. xylanivorans was also shown to have some probiotic traits, which makes it a promising candidate not only for biogas production, but also as an animal feed supplement. Genomic and proteomic analyses of cellulolytic and hemicellulolytic bacterial species aim to identify novel enzymes, which can then be cloned and expressed in adequate hosts to construct highly active recombinant hydrolytic microorganisms applicable for different biotechnological tasks.