An organic acid based counter selection system for cyanobacteria

Area of Science:

• Microbiology
• Biotechnology
• Synthetic Biology

Background:

• Cyanobacteria are crucial for photosynthesis and carbon fixation research.
• They hold potential for metabolic engineering of fuels and chemicals.
• Advanced genetic tools are needed for Synechococcus sp. PCC 7002.

Purpose of the Study:

• To develop a novel counter-selection method for cyanobacteria.
• To enable efficient genetic manipulation in Synechococcus sp. PCC 7002.
• To facilitate markerless gene deletions and insertions.

Main Methods:

• Utilized organic acid toxicity (acrylate, 3-hydroxypropionate, propionate) as a selective pressure.
• Developed an acrylate counter-selection based on loss-of-function mutations in the acsA gene.
• Applied the method for DNA fragment insertion into acsA and glpK loci.

Main Results:

• Identified acrylate, 3-hydroxypropionate, and propionate as inhibitory to Synechococcus sp. PCC 7002.
• Demonstrated that acsA loss-of-function mutations confer resistance to acrylate.
• Successfully used acrylate counter-selection for genetic engineering in Synechococcus sp. PCC 7002.

Conclusions:

• The novel acrylate counter-selection method enhances genetic engineering capabilities in cyanobacteria.
• This technique supports the construction of markerless gene deletions and insertions.
• The method is potentially applicable to other cyanobacterial species like Synechocystis sp. PCC 6803.