Diversity of cyanobacterial flora of Bakreswar geothermal spring, West Bengal, India-II

Cyanobacteria in microbial mats are described from four sites of an alkaline thermal spring at Bakreswar located in the district Birbhum of West Bengal. Four types of mats are recognized based on their colour and on the predominance of different cyanobacterial species. The four types were dominated by: i) Synechococcus, ii) Leptolyngbya, iii) Oscillatoria and iv) Fischerella. Sixteen morphospecies belonging to fourteen genera of cyanobacteria from four orders were isolated. Thermosynechococcus, Thermophilic Synechococcus, 2 species of Phormidium, 2 species of Leptolyngbya, Gloeocapsa, Calothrix and Fischerella were isolated using BG-11 medium at a light intensity of 25–30 μmol photons m-2s-1 and a temperature of 37 ± 2°C. Most abundant were Thermosynechococcus elongatus, thermophilic Synechococcus lividus, Leptolyngbya fragilis and Leptolyngbya laminosa. Some of the isolated strains and mat samples were characterized by their pigment profile. Canonical correspondence analysis (CCA) showed that temperature was the main factor controlling species occurrence. L. laminosa dominated all four sites at temperatures of 38–60°C.