The 96-well twin-layer system: a novel approach in the cultivation of microalgae

A novel system for the growth and maintenance of microalgae has been developed that allows the cultivation of a large number of strains with little manual effort. The system is based on a 96-well microtiter plate in which a membrane filter constitutes the bottom of each well. Algal strains are immobilised on the membranes and provided with culture medium through contact with layers of glass fibre located beneath the membranes in a special cultivation chamber. The configuration effectively separates culture medium from algal cells which allows the simultaneous exchange of the culture medium for 96 strains within a few minutes without the need to transfer the algae. If necessary, algal strains can be transferred using multi-channel pipettes. We demonstrate that a large variety of microalgal strains including delicate flagellates can be reliably grown in the system under axenic conditions and without cross-contamination. As an array system, the 96-well twin-layer system using immobilised algae is also amenable to high-throughput and massively parallel applications increasingly sought after in algal bio- and environmental technology.