(440b) Transcriptome Analysis of Ethanol-Tolerant Clostridium Thermocellum and Kinetic Modeling of Its Carbon Metabolism | AIChE

(440b) Transcriptome Analysis of Ethanol-Tolerant Clostridium Thermocellum and Kinetic Modeling of Its Carbon Metabolism

Authors 

Sui, S. - Presenter, University of Minnesota

Clostridium thermocellum, an anaerobic, thermophilic bacterium, has been proposed for the consolidated bioprocessing of converting lignocellulosic materials into ethanol. This work mainly focuses on analyzing the transcriptome dynamics of C. thermocellum during different growth stages and exploring the gene-trait relationship of ethanol-tolerant strain. Furthermore, a kinetic model for carbon metabolism of C. thermocellum was constructed to facilitate the understanding of interplay between metabolic regulation and ethanol tolerance.

The whole genome microarray for C. thermocellum ATCC 27405 was constructed using NimbleGen 4x72K platform. Cells were cultivated in both complex medium (GS-2) and chemically defined medium (MJ). Ethanol-tolerant strains were obtained by serial transferring cells in medium with an increasing concentration of ethanol. The time profile of transcriptome of the ethanol-tolerant strain that showed sustained growth at 2% (w/v) ethanol was compared to that of the wild type, and the kinetically differentially expressed genes between ethanol-adapted strain and wild type were identified.

Microarray measured transcript levels were employed as an estimate of the enzyme abundance in the mathematical model for carbon metabolism of C. thermocellum. The rate equations, using traditional King-Altman method steady state kinetics, took most of the known allosteric effects into consideration. The measured fluxes at different growth stages and various culture conditions including ethanol and lactate inhibitory conditions were used to assess the importance of feedback regulation.

This works provides a framework on systematic study of ethanol tolerance, and will provide insight on developing a metabolic and process engineering strategy for enhancing ethanol productivity in C. thermocellum based process.