Clostridium thermocellum is an anaerobic bacterium. It thrives at extremely high temperatures. And it has a remarkable ability to convert plant cellulose into ethanol, hydrogen and other chemical feedstocks, which is why researchers like J.H. David Wu, professor of Chemical Engineering and of Biomedical Engineering, are intensely interested in this bacterium’s potential for producing biofuels.

But there are some hurdles that need to be overcome, which was the subject of Wu’s plenary lecture at the 12th International Symposium on the Genetics of Industrial Microorganisms (GIM), held in June in Cancun, Mexico. The meeting, held every four years, is considered one of the most important in the field of fermentation technology. Wu delivered his lecture, entitled “Regulation of Cellulolytic Enzymes and Metabolic Pathways in Clostridium thermocellum,” to more than 1,000 attendees from around the world.

Clostridium thermocellum uses cellulosomes –multi-enzyme complexes on the bacterium’s surface --  to accomplish the conversion of cellulose. These cellulosomes are “intricate and elegant molecular machines designed for cellulose degradation,” Wu notes, but the yield of ethanol is low, in part because branched fermentation pathways also produce hydrogen, acetate, formate and lactate. Metabolic controls of these pathways are complicated and remain largely unknown. Elucidating the molecular events governing the metabolic controls will be critical for improving the bacterial strain for bio-fuel production.

 Wu’s lecture focused on identification of DNA-binding factors, or transcription factors, that modulate the pertinent metabolic pathways leading to biofuel production. He presented the discoveries of new transcription factors and metabolic pathways in this bacterium that were made in his lab.

Wu’s lab has been studying Clostridium thermocellum for more than 25 years.  He is one of the most recognized researchers in this field. He became interested in Clostridium thermocellum because the microorganism is capable of converting plant biomass in a single step by its ability to produce biomass-degrading enzymes (the cellulosomes), carry out biomass degradation, and simultaneously ferment the resulting sugars to ethanol or hydrogen. Not many microorganisms have these capabilities.  As a result of his and others’ work, the bacterium has become the best-studied microorganism for single-step biomass conversion, or Consolidated Bioprocessing (CBP). Wu hopes to continue this project with the aim of elucidating molecular events underlining bio-degradation of cellulose – the world’s most abundant biomaterial and developing industrial strains for CBP leading to the commercial production of biofuels.