(599f) Butanol Production from Eastern Redcedar
Eastern redcedar is one of 13 juniper species in the US that adapts well to various soils, climate conditions and topographies. Redcedar is considered as an invasive species in Oklahoma and across grasslands in the Central Plains due to its encroachment, reducing ground water yields and increasing the risk of wildfires. According to the Natural Resources Conservation Service, the encroachment of redcedar resulted in an estimated loss of $447 million in 2012 to the state of Oklahoma. In addition to the high value essential oil extracted from redcedar, this invasive tree presents new opportunities as a source of feedstock for the production of biofuels (butanol and ethanol). Butanol has higher energy density and less hygroscopicity than ethanol, which makes it more compatible with current fuel infrastructure. Butanol can also be upgraded to jet and diesel fuels. The overarching objective of this study was to develop a process for butanol production from redcedar by pretreatment, enzymatic hydrolysis, detoxification and fermentation of redcedar hydrolysates. Redcedar was pretreated using acid bisulfite method. Accelerase 1500 was used to hydrolyze pretreated redcedar followed by fermentation using Clostridium acetobutylicum ATCC 824. The overall wood glucan to glucose yield obtained after 48 h of enzymatic hydrolysis was between 80% and 90%. C. acetobutylicum grew poorly in the undetoxified redcedar hydrolysate, resulting in the production of only 1.1 g/L butanol. Microbial inhibitors in the redcedar hydrolysates were identified. Redcedar hydrolysates were detoxified by activated carbon. Acetone-butanol-ethanol (ABE) fermentation with the detoxified hydrolysate produced approximately 13 g/L butanol and 19 g/L total ABE, similar to the control (glucose). The results from this study underscore the potential for bioconversion of invasive species of junipers and other biomass feedstock to butanol, which can be further upgraded to jet or diesel fuels.