Comparative study of total soluble proteins including phycobilins and isoenzymes of a unicellular blue-green alga Synechococcus cedrorum (parent) and its antibiotic resistant strains was made by gel electrophoresis. Experiments revealed total 24, 21, 21 and 22 protein bands respectively in parent, polymyxin resistant, streptomycin resistant and penicillin resistant strains of the alga. In each strain phycobilins other than phycocyanin were absent. All the strains showed two phycocyanin bands except in streptomycin resistant strain in which one band was observed. One phycocyanin band was common to all. Isoenzymes of peroxidase, gluta-mate dehydrogenase, acid and alkaline phosphatase were found in all the strains with difference in the band pattern in each case. On the basis of the position of protein band and isoenzymes on gels it was possible to distinguish the four strains of the alga.
