Monday, April 19, 2010
1-34

Cellulose and xylan fermentation by Caldicellulosiruptor obsidiansis

Jonathan R. Mielenz, Miguel Rodriguez, Scott Hamilton-Brehm, Choo Hamilton, and Babu Raman. Biosciences Division and BioEnergy Science Center, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831

Caldicellulosiruptor obsidiansis is an extreme thermophilic Gram positive bacterium isolated from the hot spring Obsidian Pool, located in Yellowstone National Park. This bacterium is capable if utilizing a broad range of carbohydrate substrates especially hemicellulose and cellulose growing at 60-80 deg C. Fully instrumented fermentors were used to cultivate C. obsidiansis while growing on  model substrates including cellulose (Avicel) and xylan from Birchwood in a mineral medium with define additives. These fermentations yielded predominantly acetate up to 5 g/L plus low levels of lactate and ethanol (<0.5g/L). While this thermophilic microorganism grows well on cellulose, its growth was stimulated by xylan yielding simultaneously xylan and cellulose consumption.  Upon metabolizing a majority of the xylan, the microorganism continues cellulose utilize substrate in a non-growth mode producing primarily acetic acid as fermentation product. Transferring an inoculum from batch fermentor to batch fermentor over a period of 17 days permitted selection of an adapted strain able to produce over 50% more acetate than the original parent. The nature of the apparent acetate tolerant strain is under investigation as a potential inhibitor resistant variant.

See more of Poster Session One Sponsored by Genencor
See more of General Submissions

See more of The 32nd Symposium on Biotechnology for Fuels and Chemicals (April 19-22, 2010)