As the price of fossil fuels increase with diminishing reserves biofuel production for transportation is seen as a viable alternative for current as well as future energy demands. Microbial biofuel generation from lignocellulosic plant materials holds great promise with H2 being regarded as the gold standard since only water vapor is emitted when burned. Although the potential exists for this to be an economically viable substitute several issues are still to be resolved. Lignocellulosic plant material contains cellulose hemicellulose and lignin. Cellulose is comprised of the sugar glucose while soluble hemicellulose is made up of pentoses and hexoses. Lignin is heterologous and functions as part of plant cell walls. Before microbial fermentation can occur the lignin must be separated and removed. Steam blasting separates lignin and (hemi)cellulose but requires electricity for steam generation usually a natural gas or coal dependent step. This results in high net CO2 production and releases biologically inhibitory compounds requiring a detoxification step. Acidic or alkaline pre-treatments can also be used but are usually performed at high temperatures and so require detoxification as well as neutralization for typical fermentations. Overall the process is relatively inefficient and is still fossil fuel dependent which is counterproductive to the goal of reducing greenhouse gas emissions.
The present work addresses several issues. With this amended process lignocellulosic pretreatment can be performed using existing technologies and likely without the need for detoxification. Neutralization is not required and so the immediate benefit is a more stream-lined and cost efficient process. The microorganism used in this process was isolated from nature and is capable of hydrogen production rates and molar yields similar to those found in the literature; either naturally occurring or genetically engineered. This microorganism appears to be amenable to larger scale commercial or industrial applications for the production of hydrogen as a biofuel using both pentose and hexose sugars derived from lignocellulosic materials. This is accomplished with no dependency of fossil fuels anywhere in the process. Not only is CO2 not generated but the process actually uses CO2 thereby surpassing the standard of being carbon neutral while also representing a more streamlined and thus cost efficient process for...