Inactivation of invertase enhances sucrose production in the cyanobacterium Synechocystis sp. PCC 6803.

Sucrose is naturally synthesized by many cyanobacteria under high salt conditions, which can be applied to produce this widely used feedstock. To improve sucrose production with the moderate halo-tolerant cyanobacterium Synechocystis sp. PCC 6803, we identified and biochemically characterized the sucrose-degrading invertase. Inactivating the invertase encoding gene sll0626 (inv) significantly increased cellular sucrose levels; interestingly sucrose over-accumulation was also observed under NaCl-free conditions. The subsequent inactivation of inv in the mutant ΔggpS, which cannot synthesize the major compatible solute glucosylglycerol, resulted in further enhanced sucrose accumulation in the presence of 1.5 % NaCl. Then, inv mutation was introduced into the previously obtained sucrose-producing strain WD25 (Du W, Liang F, Duan Y, Tan X, Lu X. Metab Eng 2013;19:17-25), which resulted in almost 40 % higher sucrose accumulation. These findings show that invertase is an interesting target in obtaining efficient sucrose production in cyanobacterial host cells.