2.6. Measurement of whole cell O2 evolution and respiration
The rate of photosynthesis in treated and untreated cells ofAnabaena PCC 7120 were measured in terms of photosynthetic oxygen evolution using Clark type O2 electrode (Digital oxygen system model-10, Rank Brothers, U.K). After 72 h of growth, cyanobacterial cells were harvested and the cell suspension were illuminated under the saturating light intensity of 360 μmol photons m−2 s−1 PAR in a temperature controlled air tight reaction vessel, at 25 °C for 3 min. Respiration rate was measured in the darkness with the help of same instrument in terms of O2 consumption. Photosynthetic oxygen evolution rate was expressed as μmol O2 evolved (mg–1 Chl a ) h–1 and respiratory rate was expressed as μmol O2 consumed (mg–1 Chl a ) h–1.