Characterization of manganese superoxide dismutase from a marine cyanobacterium Leptolyngbya valderiana BDU20041

L. valderiana BDU 20041, a filamentous, non-heterocystous marine cyanobacterium showed tolerance to the tested dye (C.I. Acid Black 1) which is evident by increased in biomass (i.e.) chlorophyll a. The other noticeable change was the total ROS production by culture dosed with dye compared to the control cultures. This prolonged incubation showed sustenance, implying that cyanobacteria maintain their antioxidant levels. The third significant feature was a two-fold increase in SOD activity of dye treated L. valderiana BDU20041 suggesting the role of SOD in alleviating oxidative stress via Asada-Halliwell pathway. Hence, the organism was PCR amplified for SOD gene resulting in an amplicon of 550 bp. The sequence analysis illustrated the presence of first three residues involved in motif; active site residues at H4, 58 and D141 along with highly conserved Mn specific residues. The isolated gene shared 63.8% homology with MnSOD of bacteria confirmed it as Mn isoform. This is the hitherto report on SOD gene from marine cyanobacterium, L. valderiana BDU20041 of Indian subcontinent.Generation of Reactive Oxygen Species (ROS) coupled with induction of SOD by marine cyanobacterium, L. valderiana BDU20041 was responsible for alleviating stress caused by an azo dye, C. I. Acid Black 1. The partial SOD gene has been sequenced and based on the active site, motif and metal specific residues; it has been identified as Mn metalloform.Cyanobacteria, the oxygen-evolving photosynthetic prokaryote originated ~3.5 billion years ago, occupy a credential position between pro- and eukaryotes [1]. The resultant tandem operation of two photosystems is now known as oxygenic or plant-type photosynthesis [1]. This marked the turning point in the evolution of earth, opening up the era for aerobes. For the survival of cyanobacteria with oxygenic photosynthesis, the selection pressure led to the evolution of SODs [2-7]. Cyanobacteria are well documented for its ability to maintain the antioxidant l