ABSTRACT
The massive usage of petroleum and petroleum products in the last decade, with the consequent reverse effect on minimizing consumption of these unsustainable resources, has increased the demand for the development of renewable sources [1,2]. Currently, based on the carbon neutrality concept, two sources of biofuels have entered the marketplace; ethanol from cellulosic materials and biodiesel from soybean or palm oil [3]. The bioconversion of lignocellulosic materials is a challenging process which requires two steps. During the bioconversion process, the lignin and the hemicellulosic parts are first degraded into simpler sugars and/or organic acids, followed by a deoxygenating step to produce a liquid fuel [4]. De-
sign of a genetically modified microorganism for direct lignocellulosic biomass conversion purposes has recently been taken into consideration [5]. The production of several types of fuel through direct lignocellulosic biomass conversions has been demonstrated by various studies [6,7]. A genetically engineered E. coli capable of degrading pectin-rich lignocellulosic biomass by cellulolytic and pectinolytic activities has been developed [8]. E. coli has been considered a convenient biocatalyst in biofuel production for its fermentation of glucose into a wide range of short-chain alcohols [9,10], and production of highly deoxygenated hydrocarbon through fatty acid metabolism [11,12]. Moreover, the ability to ferment several pentoses and hexoses makes E. coli an ideal ethanologen for biofuel production [5,13].
