Mutations in hik26 and slr1916 lead to high-light stress tolerance in Synechocystis sp. PCC6803

Increased tolerance to light stress in cyanobacteria is a desirable feature for their applications. Here, we obtained a high light tolerant (Tol) strain of Synechocystis sp. PCC6803 through an adaptive laboratory evolution, in which the cells were repeatedly sub-cultured for 52 days under high light stress conditions (7000 to 9000 mu mol m(-2) s(-1)). Although the growth of the parental strain almost stopped when exposed to 9000 mu mol m(-2) s(-1), no growth inhibition was observed in the Tol strain. Excitation-energy flow was affected because of photosystem II damage in the parental strain under high light conditions, whereas the damage was alleviated and normal energy flow was maintained in the Tol strain. The transcriptome data indicated an increase in isiA expression in the Tol strain under high light conditions. Whole genome sequence analysis and reverse engineering revealed two mutations in hik26 and slr1916 involved in high light stress tolerance in the Tol strain. In this paper, the authors investigated the high light stress response in Synechocystis sp. PCC6803 and revealed two key mutations in hik26 and slr1916 using whole genome sequencing and reverse engineering. Here, the high light tolerant strain exhibited no growth inhibition in conditions up to 9000 mu mol m(-2) s(-1), which had no effect on excitation-energy flow and instead showed an increase in isiA expression.

Automated summary

A high light tolerant strain of cyanobacteria was obtained through adaptive laboratory evolution, showing no growth inhibition under conditions up to 9000 μmol m(-2) s(-1) and exhibiting an increase in isiA expression.