Future Microbial Applications for Bioenergy Production: A Perspective

The fast receding concentration of fossil fuels and the mounting global demand of energy has necessitated the production of alternate fuels to replace the conventional fossil fuels so as to counter the increased deposition of greenhouse gasses in the atmosphere, which has led to considerable climatic changes. These changes could result in catastrophic repercussions in the near future, including rising temperature and sea levels. Evidently, the utilization of fossil fuels for electricity and heat production and for transportation accounts for 25% and 14% of the total greenhouse gas emissions, respectively (IPCC, 2014). Therefore, nowadays, the production of economically feasible and eco-friendly renewable energy fuels is the world's highest demand that indicates the potential to simultaneously replace the conventional fuels and reduce the environmental concern. The use of versatile microorganisms to generate renewable energy fuels from the biomass and biological wastes can diminish this menacing concern to a large extent. The interest in the production of various biofuels using microorganisms has been steadily increasing in the recent years (Table 1) (Liao et al., 2016), particularly because of the metabolic diversity of different microorganisms that enables the production of biofuels from various substrates. For example, most of the bacteria can easily convert sugars into ethanol, and cellulolytic microbes can utilize plant-driven substrates. Cyanobacteria and microalgae possess the potential to photosynthetically reduce the atmospheric CO2 into biofuels, and methanotrophs can use methane to produce methanol (Liao et al., 2016). In addition, some of the bacteria such as Geobacter sulfurreducens and Shewanella oneidensis exhibit specific “molecular machinery” that helps transfer electrons from microbial outer-membrane to conductive surfaces (Kracke et al., 2015), subsequently, this feature can be deployed in bioelectrochemical devices for biohydrogen and bioelectricity generation. The impending need to address the challenges involved in enabling these microorganisms to become a more feasible option for replacing the conventional fossil fuels has been discussed in this paper with possible future directions.