Phycobilisome antenna deletion in a cyanobacterium does not improve photosynthetic energy conversion efficiency or productivity in a bench-scale photobioreactor system

Abstract

Light harvesting in cyanobacteria is performed by large peripheral phycobilisome antenna complexes that absorb light and transfer it to membrane integral antenna closely associated with the photosynthetic reaction center. In eukaryotic microalgae exposed to high light, truncation of the chlorophyll light harvesting antenna system results in an overall increase in cell growth and photosynthetic efficiency by reducing excess light absorption and subsequent energy dissipation on an individual cell level. In order to test this model in cyanobacteria, we used an optimized photobioreactor system for precise regulation of growth parameters and collected data over a wide range of culture conditions, including different CO2 and light regimes. Wild-type Synechocystis 6803 and a PAL mutant that lacks phycobilisomes were grown in batch-mode in these bioreactors. Our data show that lack of phycobilisome antenna do not provide an advantage to Synechocystis 6803 cells under any of the conditions tested.