Cellulose degrading microorganisms in Alaskan boreal forest soil

Abstract

"Cellulose is the most abundant organic compound on earth, and has been studied intensely. This thesis includes a review of previous studies and literature compiled on cellulose degradation and its significance to biofuel production. It also reports a study designed to advance knowledge of cellulose degrading bacteria and fungi in Alaskan boreal forest soil. This was accomplished using stable isotope probing (SIP) in soil microcosms and community analyses of organisms colonizing in situ buried Birch Tongue Depressors (BTDs). We identified which organisms incorporated a 13C cellulose label into their genomic material, finding degradation to be dominated by fungi. Fungi from the genera Sebacina, Geopyxis and Geomyces were the most prevalent in fungal ITS clone libraries. The most abundant bacterial cellulose utilizers were members of the order Sphingobacteriales, along with several unclassified Bacteria; the well-known cellulose degrader Cellvibrio was present, but found less frequently. The microbial community colonizing BTDs shared some taxa in common with bacterial SIP results, but differed from fungi identified with SIP. Using SIP, we identified a variety of soil microorganisms active in utilization of carbon from cellulose. These findings are significant for understanding fundamental ecosystem carbon cycling and may have application to cellulosic biofuel production technologies"--Leaf iii