The phycoerythrin (PE)-rich unicellular cyanobacteria Synechococcus spp. strains BO 8808 and BO 9203, from the pelagic zone of Lake Constance, exhibited different responses when cultured under low light and light stress conditions. Under light stress caused by continuous illumination at elevated light intensity, strain BO 8808 ceased growth, the PE/chlorophyl ratio was slowly reduced and the zeaxanthin content was significantly decreased. By contrast, strain BO 9203 grew faster under high light compared to low light intensities. This strain responded to increased light by a rapid reduction of the PE/chlorophyl ratio while the zeaxanthin content remained constant. Both of these alterations may have protecting effects for BO 9203 against light toxicity. In mixtures of both strains, the predominance of the light-tolerant strain BO 9203 was demonstrated by restriction fragment length polymorphism of psbA genes under light stress conditions. Apparently, strain BO 9203, isolated from an algal bloom in the spring, can cope better with high light intensities than strain BO 8808, isolated in the autumn.
Postius, C., Kenter, U., Wacker, A., Ernst, A., & Böger, P. (1998). Light causes selection among two phycoerythrin-rich synechococcus isolates from lake constance. FEMS Microbiology Ecology, 25(2), 171–178. https://doi.org/10.1016/S0168-6496(97)00093-7