Increase in intracellular proline content in Anabaena variabilis during stress conditions

Abstract

The present study deals with the effects of stress due to varying concentrations of sodium chloride, cadmium, pH and exposure to pesticides on intracellular proline accumulation in Anabaena variabilis in laboratory conditions. The stresses induced due to these changes in their growth media were expressed as decrease in growth (by 40% at pH 5; 30% at 50 mM NaCl; 80% at 50 ?M endosulphan and 55% at 10 ?M CdSO4) as measured in terms of chlorophyll a concentrations in the test organism. Low pH (5, 6) had stronger negative effect on growththan increasing alkaline pH. The cyanobacterium showed varying degree of susceptibility to increasing salt, cadmium and endosulphan concentrations. Under all these altered conditions, their intracellular proline concentration was found to increase linearly in the test organism with increase in its amount of stress inducing substances in its vicinity. Proline appears to be a stress provoked substance in A. variabilis. However, there seemed to be a breakdown in the proline synthesis mechanism when concentrations of such compounds reached toxic proportions.