Thermoanaerobacterium saccharolyticum JW/SL-YS485 is a gram positive, thermophilic, obligate anaerobe that grows in a temperature range of 37°C - 66°C and a pH range of 3.9 – 6.5. This organism can consume the majority of hydrolysis sugars found in lignocellulosic biomass as well as xylan and starch, but not cellulose, and produces ethanol, acetic acid, and lactic acid as organic fermentation products.

By using homology based gene knockout to target the L-lactate dehydrogenase and acetate kinase genes, the strain ALK was created that produces ethanol via a novel high yield pathway featuring pyruvate:ferredoxin oxidoreductase and transfer of electrons from ferredoxin to NAD. Strain ALK consistently produces ethanol at a yield of 0.46 g/g carbohydrate , and after adaptation in continuous culture, a volumetric productivity of 2.2 g ethanol L^-1 hr^-1 was achieved while growing on xylose.

T. saccharolyticum strain ALK can be used in a thermophilic simultaneous saccharification and fermentation (tSSF) process, and we show that the fermentation with this organism at 50°C lowers the requirement for added cellulase 2.5-fold relative to SSF at 37°C with S. cerevisiae. In addition, the ability of this strain to utilize xylose and other five carbon sugars makes it attractive for use in consolidated bioprocessing in conjunction with a cellulolytic thermophile such as Clostridium thermocellum.