Micro-compartmentalized cultivation of cyanobacteria for mutant screening using glass slides with highly water-repellent mark

• The droplet culture of cyanobacteria showed little toxicity using dodecane.
• The oil phase protects the medium from drying and increases CO2 supply.
• Single cell encapsulation and culture can be a powerful tool in mutant selection.

Photosynthetic microorganisms such as cyanobacteria have attracted attention for their potential to produce biofuels and biochemicals directly from CO2. Cell isolation by colony has conventionally been used for selecting target cells. Colony isolation methods require a significant amount of time for cultivation, and the colony-forming ratio is potentially low for cyanobacteria. Here, we overcome such limitations by encapsulating and culturing cells in droplets with an overlay of dodecane using glass slides printed with highly water-repellent mark. In the compartmentalized culture, the oil phase protects the small volume of culture medium from drying and increases the CO2 supply. Since a difference in cell growth was observed with and without the addition of antibiotics, this compartmentalized culture method could be a powerful tool for mutant selection.