Physicochemical behavioral changes in consort with nitrogen metabolism of cyanobacterium Anabaena PCC 7120 under arsenite regimes.

The present study was undertaken to investigate the arsenite (As III)-induced changes in the diazotrophic cyanobacterium Anabaena PCC 7120. It was observed that the growth of cyanobacterial decreased with increase in As (III) concentration. The cells exposed to As (III) showed morphological variation (deformity) due to the formation of deeper constrictions in vegetative cells. Strain showed increased heterocyst differentiation (1.6-fold higher) whereas decreased nitrogenase activity at the concentration of 40 ppm As (III). The activities of NR, NiR, urease and GS decreased with increase in As (III) concentrations and attained their minimum levels at 40 ppm of As (III). The Ca2+-dependent ATPase activity increased with increase in As (III) concentration and attained its about 2.72-fold higher level at 40 ppm of As (III). In contrast, sharp decline in Mg2+-dependent ATPase activity (28%) was recorded at 1 ppm of As (III) over untreated control. The rates of photosynthetic O2 evolution and respiration decreased with increase in As (III) concentration and attained its minimal level at 40 ppm of As (III). Therefore, this study highlighted arsenite regimes efficiently correlated with behavioral changes in consort with strain.