Potential of Selected Rumen Bacteria for Cellulose and Hemicellulose Degradation

U probavnom se sustavu biljojeda nalaze vrlo učinkoviti mikroorganizmi što razgrađuju celulolozu i hemicelulozu iz sažvakanog biljnog materijala, te ih opskrbljuju hranjivim tvarima. Osim protozoa i gljivica, razgradnji otporne (hemi)celulozne biomase u buragu znatno pridonose i bakterije. U fokusu je ovog preglednog rada opis enzimskog sustava triju predstavnika bakterija iz buraga što proizvode celulazu, i to: Ruminococcus flavefaciens, Prevotella bryantii i Pseudobutyrivibrio xylanivorans. R. flavefaciens je poznat po proizvodnji jedne od najkompleksnijih enzimskih struktura, pa bi se mogao upotrijebiti za dizajn enzimskog kompleksa za razgradnju stanične stijenke biljaka. S druge strane, bakterije Prevotella bryantii i Pseudobutyrivibrio xylanivorans proizvode jednostavne, slobodne i vrlo aktivne ksilanaze. Bakterija P. xylanivorans ima i probiotička svojstva, pa se može upotrijebiti za proizvodnju bioplina i kao dodatak krmivu. Ispitivanje je genoma i proteoma bakterija što razgrađuju celulozu i hemicelulozu usmjereno na identifikaciju novih enzima, koji se nakon kloniranja i ekspresije u odgovarajućim domaćinima mogu upotrijebiti za izradu vrlo aktivnih rekombinantnih hidrolitičkih mikroorganizama, te primijeniti u različitim biotehnološkim procesima.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