Single-cell microfluidics in combination with chlorophyll fluorescence measurements to assess the lifetime of the PSBO protein.

PSBO is an essential subunit of the oxygen-evolving complex and we recently demonstrated that its lifetime depends on environmental conditions in . To assess PSBO lifetime with a high time resolution, we employed () a microfluidic platform enabling the trapping of single cells and the parallel measurement of photosynthetic activity, and () a nitrate-inducible amiRNA line. Our microfluidic platform allowed the rapid replacement of the nutrient solution necessary for induction. It also enabled the precise monitoring of the decline in the F/F value, reflecting PSBO loss. We found that in the dark, at medium and high light intensity, the F/F value decreased with halftimes of about 25, 12.5, and 5 h, respectively. We also observed that photosynthetic activity was better sustained upon carbon limitation. In the absence of acetate, the halftimes of F/F diminishment doubled to quadrupled compared with the control, acetate-supplied cultures.