Microbial production of liquid biofuels through metabolic engineering

The total reserve of fossil fuels is depleting gradually all over the world. According to the statistical review of world energy by British Petroleum (BP 2015), the total reserve of coal, crude oil, and natural gas in the world is estimated at 892 billion tonnes, 1688 billion barrels, and 186 trillion cubic meters, respectively. The numbers seem to be huge at first glance, but based on the current level of energy consumption, it is estimated that coal would be exhausted in 2128, crude oil used up by 2067, and the last cubic meter of natural gas by 2069. The fossil fuels (e.g., diesel and gasoline) play important roles in energy supply for transportation, agriculture, industries, and so forth (Demirbas 2009). Thus, the depletion of fossil fuel could lead to an energy crisis and is becoming a serious concern for governments. Moreover, the world is facing the potential threat of global climate change, which can be principally attributed to the rising greenhouse gas (GHG) emissions from fossil fuel usage, according to the statistics by the International Energy Agency (IEA) (Ugarte et al. 2003; IEA 2015).