Development of superior clostridia microbes for next generation biofuel production

  • Supervisor: Wilfrid Mitchell (Heriot-Watt University)
  • Sponsor Company: Green Biologics Ltd
  • PhD Student: Richard Freeman

Ongoing concerns regarding security of energy supplies and the environmental impact of burning fossil fuels have stimulated research into alternative technologies.  In the transport sector, biofuels have become established as a viable substitute for oil-based fuels. While biodiesel and bioethanol are currently in use, biobutanol has many advantages which make it a superior fuel for use in combustion engines, and it is poised to make a significant impact as a renewable biofuel with an estimated $80B global market.  Solventogenic clostridia produce butanol as the principal metabolic product in the acetone-butanol-ethanol (ABE) fermentation, a successful industrial-scale process used worldwide during the 20th century, but which went into decline for economic reasons when it was unable to compete with the petrochemical industry.

Economic production of biobutanol from various renewable feedstocks requires superior and metabolically engineered strains displaying effective substrate utilization together with advanced high productivity fermentation.  Screening of a collection of clostridia for butanol production employing a range of feedstocks has identified some novel pathways and mechanisms for sugar utilisation.  In particular one strain, when grown on corn residues, secretes an enzyme(s) capable of degrading starch, but does not have an obvious α-amylase, the enzyme most commonly associated with starch degradation by bacteria.  The studentship programme will involve a detailed biochemical and molecular biological study of starch degradation in this strain. The information will be used to inform strategies for engineering strains exhibiting improved sugar uptake and solvent production, that can be tested at both lab and pilot scale.