10.22376/ijpbs.2019.10.1.p1-12 Volume 6 Issue 3 2015 (July - September) Cyanobacterial diversity under environmental extremes led us to screen Chl lessThan i greaterThan a lessThan /i greaterThan , carotenoids d and phycocyanin in cyanobacteria lessThan i greaterThan Nostoc muscorm lessThan /i greaterThan (mesophile), lessThan i greaterThan Mastigocladus laminosus lessThan /i greaterThan (thermophile) and lessThan i greaterThan Nostoc lessThan /i greaterThan 593 (Antarctic) grown at 30, 40 and 20°C, respectively. Maximum amount of Chl lessThan i greaterThan a lessThan /i greaterThan was recorded in lessThan i greaterThan N muscorum lessThan /i greaterThan (6.34 µg mg lessThan sup greaterThan -1 lessThan /sup greaterThan dry weight) over lessThan i greaterThan Nostoc lessThan /i greaterThan 593 (6.29 µg) and lessThan i greaterThan M. laminosus lessThan /i greaterThan (4.62 µg).While for carotenoids, the sequence changed to lessThan i greaterThan Nostoc lessThan /i greaterThan 593 (4.35 µg) greaterThan lessThan i greaterThan M. laminosus lessThan /i greaterThan (4.08 µg) greaterThan lessThan i greaterThan N. muscorum lessThan /i greaterThan (2.48 µg). Phycocyanin followed the same pattern as carotenoids. Maximum amount of phycocyanin was recorded in lessThan i greaterThan Nostoc lessThan /i greaterThan 593 with 154 µg over lessThan i greaterThan M. laminosus lessThan /i greaterThan with 84.7 µg and lessThan i greaterThan N. muscorum lessThan /i greaterThan with 64.52 µg mg lessThan sup greaterThan -1 lessThan /sup greaterThan dry wt. Phycocyanin was purified to homogeneity and confirmed further by SDS-PAGE. Pure phycocyanin yielded two subunits with apparent molecular mass of 14 and 15 kDa each. It is anticipated that cyanobacteria may be the ideal resource of such antioxidant proteins from the biotechnological viewpoint. AKHILESH P. SINGH,1 RAVI K. ASTHANA AND SUBHASHA NIGAM Antarctic; mesophilic; thermophilic; cyanobacteria; phycocyanin; purification 1020-1028