FIG 4.

Quantification of glycogen and polyhydroxybutyrate (PHB) in Synechocystis sp. PCC 6803 wild-type (wt), kpsM mutant, and complemented mutant strains. (A) Glycogen quantification performed by the phenol-sulfuric acid assay and normalized by chlorophyll a. (B) PHB content determined by HPLC and normalized by chlorophyll a. The TEM micrographs show the ultrastructure of Synechocystis wild-type and kpsM mutant cells, with the arrowhead indicating the intracellular accumulation of PHB in the kpsM mutant. Cells were grown in BG11 medium at 30°C under a 12-h light (50 μE m⁻² s⁻¹)/12-h dark regimen, with orbital shaking at 150 rpm. Experiments were performed in triplicate, and statistical analysis is presented (n.s., not significant [P value of >0.05]; *, P value of ≤0.05).