Progress and perspective of biosynthetic platform for higher-order biofuels

The exploitation of innate microbial capacities and/or the importation of novel diverse biosynthetic pathways have become one of the predominant research directions, with both being used to convert fermentable substrates into higher-order biofuels with long carbon chains ( > 6) approximating those of gasoline with rating octane value. However, one of the primary issues has been which microorganic biosynthetic platform is most appropriate for transformation into an efficient cell factory for the production of higher-order biofuels. It is indistinct whether such a microorganism would ultimately be engineered using a native, newly isolated strain, a recombinant strain, or a model organism as the starting host. Different biosynthetic platforms microorganisms naturally have different genetic backgrounds, thus presenting different levels of complexity for metabolic networks, the incorporation of different physiological characteristics, cell structural properties, and/or biological activities. These complexities affect strategic formulations of synthetic biology, optimization designs of systems metabolic engineering, selection of metabolic pathways, and operation process difficulties in the realm of evolutionary engineering at the systems level. Here, we offer a global review of existing research for selected, engineered microorganisms designed to produce higher-order biofuels. Our focus on these microorganisms centers on the optimal production of higher-order biofuels using the construction of novel metabolic pathways and/or the alteration of existing pathways as well as examples of their application in recent years. We also discuss potential candidate microorganic biosynthetic platform and offer insight into the circumstances under which each should be used. Finally, we highlight the perspective that developing microorganisms has great possibility, but has not been extensively explored as a viable platform. In this paper, the review is placed in contrast with Crispr-Cas9 genome editing technology that will play an increasingly important role, which can be used to overcome the complex genetic metabolic background of microorganisms at more advanced levels.