In vivo alpha-olefin production: a sustainable hydrocarbon source

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One of the main challenges our society faces is the dwindling level of oil reserves which we not only depend upon for transport fuels, but also plastics, lubricants and a wide range of petrochemicals. This application seeks to provide an answer through synthetic biology: making organisms produce "oil". Although the production of oil is mainly a biogenic process, the geochemical conversion of biological matter to oil occurs over thousands of years. Solutions that seek to reduce our dependency on fossil oil are therefore urgently needed. The direct production of hydrocarbon compounds by living organisms, bypassing the geochemical conversion of organic matter into oil, is an attractive process, but is unfortunately not part of the "mainstream" repertoire of biochemical reactions that would be required to make this an attractive sustainable alternative. Indeed, minor pathways or side-reactions resulting in the production of hydrocarbons such as alkenes or alkanes have only recently been documented. Unfortunately, these are not present in any organism to the scale and/or specificity that would support industrial application, let alone provide a valid alternative to fossil oil. However, the application of synthetic biology and metabolic engineering to modify these pathways is likely to result in innovative advances in this area. To meet these challenges, we will combine state-of-the-art enzymology and laboratory evolution techniques with synthetic biology. The first challenge is enzymatic hydrocarbon production, a process that often starts with fatty acids. The enzymes involved in converting fatty acids to hydrocarbons have only very recently been identified and many remain unstudied. Furthermore, their properties (substrate and product specificity, stability and rate) are unlikely to support an industrial scale process. We will investigate the use of a wide range of enzymes using structure-based rational engineering and laboratory evolution, in order to create a comprehensive toolkit of catalysts that we will exploit for hydrocarbon production. Ultimately, we will attempt to integrate these with various components into a bacterial strain which can convert renewables into hydrocarbons, preferentially excreted to the outside environment, creating a sustainable process. This ambitious programme addresses an urgent industrial need for reducing our dependency on fossil oil. Through enzyme design and development of new pathways, it will generate "oil"-producing organisms, hence bypassing the need to drastically adapt oil-dependent processes while reducing the associated carbon footprint. Our project will focuses in particular on production of linear alpha-olefins, a high value, industrially crucial intermediate class of hydrocarbons that are key chemical intermediates in a variety of applications, such as flexible packaging, rigid packaging and pipes, synthetic lubricants used in passenger car, heavy duty motor and gear oils, surfactants, detergents, lubricant additives and paper sizing. At present, no "green" alpha-olefin production process is available, a situation which this application seeks to change.