Effect of hydration and dehydration on initiation and dynamics of some physiological reactions in desiccation tolerant cyanobacterium Scytonema geitleri.

The effect of hydration and dehydration has been studied on extent and recovery of some metabolic reactions in desiccation tolerant terrestrial cyanobacterium Scytonema geitleri. The results show that the energy transducing reactions like photochemical reactions of photosynthesis recover first, followed by increase in ATP pool size. During later phase of hydration, appearance of energy consuming processes such as CO2 fixation and nitrogen fixation have been observed. Sensitivity of reactions during dehydration followed the pattern reverse to recovery processes.

Water binding in sub-aerial cyanobacteria.

The role of water in the maintenance of structural and functional integrity of the cell at different hydration levels has been a subject of wide understanding. Water sorption isotherms, dielectrics and IR spectroscopic techniques were used to estimate the strength of water binding and number of binding sites using D'Arcy/Watt equation on the two well reported desiccation-tolerant cyanobacteria-Scytonema geitleri and Lyngbya arboricola. The observations made with water sorption isotherms, dielectrics and IR spectroscopic techniques clearly indicate three water binding regions. Grown mats of both the cyanobacteria showed high number of water binding sites onto strong binding region compared to their dry counterparts.