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February 07, 2017

Growth rate of C. thermocellum in response to various C5 sugars

Understanding the role of pentose sugars on C. thermocellum metabolism
This work highlights the importance of removing pentose sugars during bioconversion to biofuels, which could be achieved with C5 utilizing co-cultures or engineered strains of C. thermocellum, and is the first report of a functional ArgD-type cell signaling system in a thermophilic Firmicute and further work is warranted to understand the role of cell-to-cell signaling in achieving robust fermentations of lignocellulosic biomass.

January 20, 2017

SEM image of C. bescii (blue circles) attached to cellulose walls at 48 h

Visualization of Significant Alteration of Populus biomass by C. bescii
Caldicellulosiruptor bescii targets surface cellulose and hemicellulose, but increase of surface lignin could inhibit further sugar access. Biphasic cell growth is attributed to degradation of easily accessible sugars followed by utilization of more insoluble polysaccharides.

January 10, 2017

Metabolic Adaptation Of C. thermocellum To Growth Inhibitors Released During Deconstruction Of Switchgrass
Integrated omics data of microbial growth on complex lignocellulosic biomass over time provided a detailed view of the molecular machinery (metabolites and enzymes) that reveals temporal adaptation to a complex, lignocellulose substrate — information that is critical for engineering C. thermocellum's industrial efficacy.

January 03, 2017

Engineering N-terminal End of CelA Enhances the Cellulolytic Activity of Caldicellulosiruptor bescii
To test whether alteration of the N-terminal terminus of CelA GH9 and CelA GH48 domains might improve secretion and/or catalytic efficiency of CelA, repeating aspartate tags were introduced into the N-terminal ends of these 8 domains. Introduction of repeating aspartate tags resulted in an increase in the general activity of the exoproteome and a dramatic increase in growth of C. bescii on crystalline cellulose. Most efficient cellulase systems contain highly active exocellulase enzymes capable of decrystallizing cellulose, so the observed increase in activity on Avicel bears directly upon the ability of CelA to degrade realistic biomass feedstocks destined for biofuels production.

BioEnergy Science Center one of three DOE Bioenergy Research Centers established by the U.S. Department of Energy.