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Butanol Production from Biomass at Tulane
Objectives
The main objectives of this subproject are to develop enrichment culture techniques to identify new and possibly novel bacterial strains from natural sources that catalyze acetone butanol ethanol (ABE) fermentation, and to identify culture conditions that optimize the yield of butanol. We are especially interested in discovering new ABE fermenting organisms that are capable of using cellulose as a carbon source
Progress and Status
An extensive literature survey was undertaken to understand the ABE fermentations catalyzed by bacteria of the genus Clostridium. The focus areas for this study were the metabolic pathways involved in ABE formation, microbial isolation and anaerobic cultivation in various media compositions, metabolic engineering of Clostridia, carbohydrate degrading enzymes in Clostridia and the optimization of butanol fermentations.
A laboratory has been adapted to conduct studies on butanol bioprocesses. The laboratory has workstations for microbiology work, including media preparations, incubators, chemical analysis, and bioreactor fermentations.
We decided that fecal samples from herbivorous animals, including ruminants’ have excellent potential for containing bacterial strains capable of ABE fermentation. We have established communications with the Dr. Bob MacLean who is a Senior Veterinarian at The Audubon Zoo of New Orleans and he has given us permission to collect fecal samples from which we will cultivate anaerobes. We are now in the process of collecting our first samples. Preliminary experiments were conducted to determine the suitability of media compositions (organic and inorganic) and culture vessels suitable for cultivating anaerobic microorganisms.
We developed a method where in the nutrient media was simultaneously boiled and gassed with argon and immediately filled into sterile culture bottles (with a minimal head space) and this method was found to be suitable for cultivating anaerobic bacteria. The dye resazurin was found to be a suitable indicator of the presence/absence of oxygen into the media. However, an anaerobic glove-box incubator is urgently needed for the routine manipulation of anaerobic bacteria that we are collecting and testing. Several manufacturers have been contacted including those that sell used culture boxes that have been reconditioned. We are in the process of acquiring a used and reconditioned glove box incubator. On the analytical side, gas chromatography (GC) has been used to establish conditions for quantifying acetone, ethanol, butanol, acetic acid and butyric acid. The existing GC column was found to be unsuitable for this analysis and a new GC column has been procured and is working fine.
