Jonathan Mielenz, leader of the Bioconversion Science and Technology Group in ORNL's Biosciences Division, is studying a microbe that could prove more cost effective than current methods in transforming cellulose from sources such as switchgrass and poplar trees into ethanol.

Bioconversion Science & Technology

The Bioconversion Science and Technology group performs multidisciplinary R&D for the Department of Energy's (DOE) relevant applications of bioprocessing, especially with biomass. Bioprocessing combines the disciplines of chemical engineering, microbiology and biochemistry. The Group 's primary role is investigation of the use of microorganism, microbial consortia and microbial enzymes in bioenergy research. The group in involved in multiple project both within the DOE Office of Science-funded ORNL-led BioEnergy Science Center. Recent research has focused on biomass conversion by a thermophilic bacterium Clostridium thermocellum and its ability to convert cellulose directly to ethanol and other products during fermentation. Studies have investigated the details of the numerous enzymes involved and genes expressed after exposure to a variety of types of biomass. Additionally, research within the Group has thrust ORNL into a leadership position regarding the use of microbial fuel cells for waste and process water upgrading while producing electricity. The  Group  Leader, Jonathan Mielenz also  is a co-chairman of the long running Symposium on Biotechnology for Fuels and Chemicals  in its 32nd year in 2010 in Clearwater Beach Florida in late April (   The Group actively support educational summer programs and typically hosts one to two college student and/or science teachers.  We collaborate with a variety of industries and universities and encourage contacts seeking joint project work.

This group's research interests can be grouped into four areas:

  • Production of Fuels and Chemicals  from Biomass 
  • Fundamental Research on Biological Process for Bioenergy Production 
  • Microbial Fuel Cell Development and Demonstration
  • Microbial Environmental Remediation

Our capabilities can be grouped as Microbial Fermentation, Biomass Conversion, Biochemistry, and Applied Molecular Biology for Microbial strain and enzyme development. Members of the Group are experts in novel reactors, separations, modeling, and system integration using chemical engineering principles.


During cellulose fermentation, the capacity of C. thermocellum to sense and respond to its environment increases and cells become more motile over time; however the metabolic capacity decreases progressively with time during batch growth. Transcriptomic and proteomic data suggest a well-coordinated temporal and substrate-specific regulation of cellulosomal composition in C. thermocellum. Several proteins respond specifically to the presence of 'non-avicel' substrates and are of significant interest. Future research will continue as part of the BioWnergy Science Center.

Raman B., C Pan, GB Hurst, M Rodriguez Jr, CK McKeown, PK Lankford, NF Samatova, and JR Mielenz, (2009). Impact of Pretreated Switchgrass and Biomass Carbohydrates on Clostridium thermocellum Cellulosome Composition, PLoS ONE 4(4): e5271.