Growth curves of wild-type, TAM-2, and TAM-4 mutants in outdoor photobioreactor. (a) Time-dependent course of cell concentration. All experiments were performed in 7-L hanging bag reactors, fed with air/CO2 mix modulated in order to keep the pH of the medium always below 7.1. Two runs with nine reactors, each operated in parallel, were prepared. Data are expressed as mean ± SD, n =9. (b) Picture of the outdoor plant with 7-L reactors, showing growth stage of WT and TAM after two (left), four (center), and eight (right) days from initial inoculum.