Designer Biosynthetic Pathways for Photosynthetic Biofuels and Bioproducts: Opportunities and Challenges

Abstract

With synthetic biology, genetically engineered (GE) cyanobacteria are now a potential photosynthetic platform for bioproducts, in that genetic transformation with a series of transgenes can encode for biosynthetic pathways to enable the conversion of CO2, water and sunlight to biofuels (e.g. butanol). This presentation will disclose designer biosynthetic pathways for photosynthetic production of bioproducts such as butanol and/or related higher alcohols from carbon dioxide and water. The designer photosynthetic organisms are created such that the endogenous photobiological regulation mechanism is tamed, and the reducing power (NADPH) and energy (ATP) acquired from the photosynthetic process are used for synthesis of butanol and/or related higher alcohols from carbon dioxide and water. This photosynthetic biofuels‐production method eliminates the problem of recalcitrant lignocellulosics by bypassing it. Furthermore, this approach enables the use of seawater and/or groundwater for photobiological production of higher alcohols (such as 1‐butanol) without requiring freshwater or agricultural soil, since the designer photosynthetic organisms can be created from certain marine algae and/or cyanobacteria that can use seawater and/or certain groundwater. However, there are still significant challenges. For example, it is also important to understand the bio‐risk of such organisms before the synthetic biology approach could be used for commercial application. Recently, using plasmid‐transformed cyanobacteria, we experimentally demonstrated that the horizontal gene transfer from GE cyanobacteria to E. coli could occur as soon as 1–3 days of liquid co‐cultures. On the other hand, there was no detectable transfer event for the integrated transgenes so far. These results suggested that even though GE cyanobacteria carrying integrated transgenes possess a more permanent change in the genomic DNA, the bio‐risk of these GE organisms in the context of gene sharing is less severe than plasmids‐carrying GE cyanobacteria. In any case, biosafety is still a potential challenge that must also be addressed.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.