Rapid and Simple Assay of the Viability of Crustose Coralline Algae

Abstract

Viability of crustose coralline algae was measured using three oxidation-reduction indicators: 2,3,5-triphenyl tetrazolium chloride (TTC), 3-(4,5-dimethyl-tiazolyl-2)-2,5-diphenyl tetrazolium chloride (MTT) and alamar blue. The two tetrazolium salts, TTC and MTT, were reduced to form colored formazan in living corallines, but were not reduced in dead corallines. These formazans were extracted and quantified spectrophotometrically. Bluish violet MTT-formazan could be distinguished easily from red phycoerythrin and was useful for judging the viability of crustose corallines. Alamar blue indicated the viability visually and spectrophotometrically by changing the color of the culture medium. The alamar blue assay did not cause any damage to the growth of crustose corallines, indicating that it is suitable for estimating the viability of an individual plant over time. These results suggested that MTT and alamar blue can be used for rapid and simple assay in ecological and physiological investigations for crustose corallines.