Strain and bioprocess improvement of a thermophilic anaerobe for the production of ethanol from wood.

Background: The thermophilic, anaerobic bacterium Thermoanaerobacterium saccharolyticum digests hemicellulose and utilizes the major sugars present in biomass. It was previously engineered to produce ethanol at yields equivalent to yeast. While saccharolytic anaerobes have been long studied as potential biomass-fermenting organisms, development efforts for commercial ethanol production have not been reported.

Genome-scale resources for Thermoanaerobacterium saccharolyticum.

Background: Thermoanaerobacterium saccharolyticum is a hemicellulose-degrading thermophilic anaerobe that was previously engineered to produce ethanol at high yield. A major project was undertaken to develop this organism into an industrial biocatalyst, but the lack of genome information and resources were recognized early on as a key limitation.

Results: Here we present a set of genome-scale resources to enable the systems level investigation and development of this potentially important industrial organism.

Anaerobic detoxification of acetic acid in a thermophilic ethanologen.

Background: The liberation of acetate from hemicellulose negatively impacts fermentations of cellulosic biomass, limiting the concentrations of substrate that can be effectively processed. Solvent-producing bacteria have the capacity to convert acetate to the less toxic product acetone, but to the best of our knowledge, this trait has not been transferred to an organism that produces ethanol at high yield.

Results: We have engineered a five-step metabolic pathway to convert acetic acid to acetone in the thermophilic anaerobe Thermoanaerobacterium saccharolyticum.

Ethanol and anaerobic conditions reversibly inhibit commercial cellulase activity in thermophilic simultaneous saccharification and fermentation (tSSF).

Background: A previously developed mathematical model of low solids thermophilic simultaneous saccharification and fermentation (tSSF) with Avicel was unable to predict performance at high solids using a commercial cellulase preparation (Spezyme CP) and the high ethanol yield Thermoanaerobacterium saccharolyticum strain ALK2. The observed hydrolysis proceeded more slowly than predicted at solids concentrations greater than 50 g/L Avicel. Factors responsible for this inaccuracy were investigated in this study.

Response surface methodology (RSM) to evaluate moisture effects on corn stover in recovering xylose by DEO hydrolysis.

Response surface methodology (RSM), based on a 2(2) full factorial design, evaluated the moisture effects in recovering xylose by diethyloxalate (DEO) hydrolysis. Experiments were carried out in laboratory reactors (10 mL glass ampoules) containing corn stover (0.5 g) properly ground.

Xylitol production from DEO hydrolysate of corn stover by Pichia stipitis YS-30.

Corn stover that had been treated with vapor-phase diethyl oxalate released a mixture of mono- and oligosaccharides consisting mainly of xylose and glucose. Following overliming and neutralization, a D-xylulokinase mutant of Pichia stipitis, FPL-YS30 (xyl3-∆1), converted the stover hydrolysate into xylitol. This research examined the effects of phosphoric or gluconic acids used for neutralization and urea or ammonium sulfate used as nitrogen sources.

Rapid 2,2'-bicinchoninic-based xylanase assay compatible with high throughput screening.

High-throughput screening requires simple assays that give reliable quantitative results. A microplate assay was developed for reducing sugar analysis that uses a 2,2'-bicinchoninic-based protein reagent. Endo-1,4-beta-D-xylanase activity against oat spelt xylan was detected at activities of 0.

The ribosome-inactivating protein restrictocin deters insect feeding on Aspergillus restrictus.

The fungus-feeding beetle, Carpophilus freemani, consumed equal quantities of young mycelia, fewer phialides bearing mature spores and much fewer phialides bearing developing spores of Aspergillus restrictus compared to those of Aspergillus nidulans when tested in diet choice assays. The degree to which specific fungal structures were consumed was inversely related to the localization of high levels of restrictocin, a ribosome-inactivating protein, to those structures. Pure restrictocin added to the insect diet at 1000 p.