Abstract
The way cyanobacteria can adapt to the most seemingly challenging environments provides an opportunity to understand how molecular mechanisms to aid in cyanobacterial survival. Synechocystis sp. PCC 6803 is a cyanobacterium that can grow at a wide pH range making it an interesting organism to investigate for biofuel applications by potentially reducing unwanted bacterial contaminants Two gene candidates, sll1392 pfsR and slr1501 (hypothetical gene) were chosen due to previous research that noted considerable down-regulation when Synechocystis 6803 cells were transferred from pH 10 buffered medium to pH 7.5 buffered medium, indicating potential involvement in high pH acclimation. In this study, mutant strains that lacked sll1392 and slr1501 were investigated and subjected to high pH, increased light,
ethanol, sodium chloride ( and limited iron conditions.
The ∆ sll1392 mutant strain displayed multiple phenotypes ( increased growth in 0.75 M NaCl, ( ethanol sensitivity and iii iron sensitivity. The ∆ slr1501 mutant strain displayed (ethanol tolerance and ( growth in limited iron. A double knockout strain (removal of slr1501 and sll1392 displayed: ( high light sensitivity and ( increased growth in iron-limited conditions. To further explore the role of slr1501 an overexpression strain slr1501 OE) wascreated which exhibited increased growth when subjected to 0.75 M NaCl.
Both the Sll1392 and Slr1501 proteins were shown to be conserved in 5 6 and 45 other cyanobacterial species, respectively. The results indicated the genes are not solely responsible for pH regulation nor are required for Synechocystis 6803 survival but they do have a role in
stress response. This research highlights how pH influences growth alone, and when further stressors are added. Investigating genes that are involved in stress regulation could potentially aid biofuel production by targeting ethanol or NaCl tolerance to reduce overall production costs and improve output yield that could aid a path in a greener renewable future.