Effect of Diethyl Sulphate on Morphology, Growth and Pigment Accumulation of Spirulina platensis

Diethyl sulphate is an alkylating agent that transfers alkyl groups to biologically important macromolecules like DNA. In order to find out the effect of DES on growth and biopigments of Spirulina platensis, the cultures were treated with various concentration of DES (0.0001%, 0.001%, 0.01% and 0.1%) for 1 hr, 2 hr and 4 hr duration. The growth of cultures was followed through optical density, dry weight and pigment estimation (estimation of Chlorophyll a, carotenoids and phycobiliproteins). All the four concentrations tried, showed varied degrees of damage and decreased growth and pigment contents in all the durations of mutagen exposure. In all of the concentrations, 0.1% was found to be the most effective and the least effective was 0.0001% concentration in all of the durations of exposure. Genetic variability were also seen as straightened and uncoiled filaments in 2 hr and 4 hr exposed cultures, these permanent morphological variants are evident of genetic changes caused by DES. The survival of cultures among different treatment times under each individual concentration of DES used also decreased from shorter (1 hr) to longer treatment time (4 hr). In the combination of longer treatment time with higher concentration of DES applied to the cultures of S. platensis was found to be synergistic effect of treatment.