Engineering Synechocystis sp. PCC 6803 as a sustainable biotechnology platform through synthetic biology tools

Synthetic biology has shown its potential to build programmable biological devices with various metabolic functions to fulfill societal needs.  These devices have almost exclusively been built in organisms that depend on organic compounds as their energy and carbon sources while cyanobacteria can utilize atmospheric carbon dioxide and light.  Creating synthetic biology tools for cyanobacteria can enhance their programmability and expand their metabolic functions, thus increasing the utility of these organisms as sustainable biotechnology platforms for a greater diversity of compounds.  In particular, synthetic transcriptional control of metabolic processes can be employed to express pathway and regulatory genes in precise amounts at a defined stage.  This allows for process tuning that maximizes production by 1) reducing metabolic burden during the growth phase, 2) optimizing generation of target compounds which may be toxic to the cells, and 3) regulating enzyme expression in response to the appropriate intracellular conditions.  Utilizing the fumarate and nitrate reduction system from Escherichia coli as an oxygen sensor for Synechocystis sp. PCC 6803, production of enzymes that are inactivated by oxygen can be transcriptionally coordinated with intracellular oxygen levels.  Inducible promoters that respond to exogenous compounds also provide synthetic transcriptional control of various metabolic functions.  We will present progress on creating synthetic biology tools for cyanobacteria, including tuning of our intracellular oxygen sensor and developing inducible promoters to improve chemical production by Synechocystis sp. PCC 6803.