EBI Personnel Directory Mackie, Roderick
This project examines the chemical and nutrient composition of two potential sources (corn stover and energy cane) of lignocellulosic stillage residues from bioenergy crops. These stillage sources form the substrate for anaerobic digestion studies. Anaerobic digestion is carried out at mesophilic (40°C) and thermophilic temperature (60°C) in a Conventional Stirred Tank Reactor (CSTR) and Hybrid reactor (combining an Upflow Anaerobic Sludge Blanket (UASB) and anaerobic filter). Benchtop fermenters are used to study fundamental aspects of microbial ecology and performance characteristics in the system. Molecular microbial ecology and deep sequencing approaches focus on key functional groups involved in the hydrolysis of polymers, production and utilization of hydrogen (interspecies hydrogen transfer) and acids (acid oxidation) and methanogenesis (terminal carbon and electron flow). Started in 2012.
We propose to study the Acetone-Butanol-Ethanol (ABE) fermentation in a diverse set of strains obtained from culture collections as well as industrial strains of solventogenic Clostridia: 1) Obtain a wide selection of existing strains from culture collections that are representative type strains or have been used for industrial fermentations. We intend to build a large collection of strains representing the four main species groups. 2) Obtain a newly isolated set of environmental cultures and strains that are capable of solvent production at mesophilic and thermophilic temperatures. We will supplement the extant strains above by bringing into culture a fresh set of isolates of solventogenic Clostridia with the emphasis on thermophilic bacteria capable of producing alcohols and solvents using enrichments and other standard anaerobic laboratory techniques. 3) Screen the above collections for substrate range, diversity of solvent ratios, yields and titres, phage typing as well as genetic tractability to generate a versatile and adaptable set of isolates for future industrial application. The evaluation of the genetic transformability parameters of strains used in the ABE fermentation such as cell viability, transformation efficiency and frequency of transformation are essential steps to identifying which strains are the most adequate for breeding programs and which strains are best suited for genetic and metabolic engineering approaches to enhancing the ABE fermentation.