Metabolic engineering of cyanobacteria

• Post by: wangikar_8khp2z
• 10:50AM Apr 11, 2018
• Comments off

Cyanobacteria, which constitute a quantitatively dominant phylum, are well known for their ability to carry out oxygenic photosynthesis. This prokaryotic group has been attracting attention in biofuel applications due to its favourable physiological characteristics, photosynthetic efficiency and amenability to genetic manipulations.

Figure 5. Metabolic oscillations in cyanobacteria. Profiles of (A) CO2 and (B) O2 in the exit gas (cyan), pH of the growth medium (brown), (C) intracellular glycogen (red) content and growth (green) in the fourth day of entrainment under alternating light/dark cycles (LD) followed by constant light (LL). The horizontal bar below the X-axis denotes the light (clear), dark (shaded) and subjective dark (shaded with slanted lines) phases.

We have engineered cyanobacteria to produce a number of bulk chemicals including 2, 3 butane-diol pentadecane and heptadecane. This model driven approach involved knocking down of key carbon venting pathways that cause a significant drain on the fixed carbon. Additionally, we have developed novel expression systems and inducer-free promoters that activate gene expression during the desired phase of light in this phototrophic phylum.

Broader Impact- Cyanobacteria are poised to provide an alternative to fossil fuels and petroleum derived products. The strains developed by us accumulate ~15% w/w alkanes. We hope to develop these further to make them commercially viable. Importantly, these strains are isolated locally and can tolerate high levels of CO₂, temperature and light. Current work involves engineering of strains to overproduce products that have applications as pharmaceutical intermediates, food colorants and flavors. The abundance of reducing equivalents in photosynthetic organisms make it an interesting platform to produce biomolecules which are reduced.

Figure: An overview of the process to develop a synthetic standardized and predictable biological system incorporating engineering principles. a General scheme of standardized synthetic biology approach for developing engineered biological systems. b Standardized notations of the biological parts adapted from (Endy 2005)

Figure: Novel LC-MS/MS Workflow For Untargeted Acquisition of Mass Isotopologue Distribution of Metabolites and Fragments