Sunday, May 3, 2009
6-14
Isolation and Cultivation of Cell Wall Decomposing Bacteria from Plant Biomass Decaying Communities
Safiyh Taghavi1, Luen-Luen Li1, Shi-You Ding2, Michael E. Himmel2, and Daniel Van der Lelie1. (1) Biology, Brookhaven National Laboratory, 50, Bell Avenue, Upton, NY 11973, (2) Chemical and Biosciences Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401
Natural decomposition of biomass employs hydrolytic enzyme cocktails, often provided by complex microbial communities. The objective of this study is to isolate and cultivate bacteria from lignocellulosic biomass degrading communities that decay poplar chips, corn stover and switch grass biomass, and explore their metabolic potential for cell wall decomposition. From a microbial poplar biomass decay community, both the aerobic and anaerobic biomass decay zones were taken and used to initiate enrichment cultures. Eight bacterial strains were isolated from an aerobic enrichment, and twenty-one strains were isolated directly from the biomass under an anaerobic condition. Strains were further identified by 16S rRNA sequencing and characterized by carbon source utilization. Potential glycosyl hydrolase activity was observed within these isolates: Bacillus sp. strain 1046 showed clearing on CMC-plates; Clostridium sp. strains 880 and 883, C. akagii strains 885 and 887, C. aciditolerans strain 886, and Enterobacter sp. strain 889 showed growth on CM3-medium with cellulose as sole carbon source. Strain Clostridium sp.VIII and the two enriched consortia were able to grow on washed corn stover, thus biomass composition and glycosyl hydrolase were also tested. Xylosidase, cellobiosidase, and arabinosidase activities were detected in these samples. Most interestingly, two isolates from decaying corn stover biomass showed strong clearing zones on plates with Sigmacell as sole carbon source in an anaerobic growth. Both strains belong to the Clostridium sp. (16S rRNA sequencing), and characterization of these strains are currently in the process.