2.3. Transformation of Synechocystis cells
Synechocystis wild type cells grown in 50 mL of liquid BG11
medium without antibiotic for 2–3 days (OD730 6 0.5) were collected
by centrifugation (2790g) of the culture at room temperature
for 5 min, resuspended in fresh medium to concentrate cells
suspension to OD730 2.5 in microcentrifuge tube. At least 10 lg
of plasmid DNA was added into 500 lL of cell suspension in a
microcentrifuge tube. The mixture was incubated under growth
condition for at least 6 h before spreading on a 0.45 lm sterile
hydrophilic mixed cellulose ester membrane filter placed over a
BG11 agar plate and incubated for 24 h. The filter was then placed
on a selective BG11 agar plate containing 30 lg/mL chloramphenicol.
Colonies were normally obtained from the selective agar plate
within 3 weeks of incubation. To ensure correct integration, the
genes of OE strains were analyzed by PCR using gene specific primers
(Table 2).