Samit Ray

The Study of Cyanobacterial Flora from Geothermal Springs of Bakreswar, West Bengal, India

Geothermal springs in India, formed as a result of volcanic or tectonic activities, are characterized by high temperature and relatively abundant reduced compounds. These thermal springs are inhabited by characteristic thermophilic organisms including cyanobacteria. Cyanobacteria are among the few organisms that can occupy high temperature aquatic environments including hot springs. In alkaline and neutral hot springs and streams flowing from them cyanobacteria can form thick colourful mats that exhibit banding patterns. The present investigation involves study of mat forming cyanobacterial flora from hot springs located in Bakreswar, West Bengal, India. The important species found are Synechococcus bigranulatus, S. lividus, Gloeocapsa gelatinosa, G. muralis, Phormidium laminosum, P. frigidum, Oscillatoria princes, O. fragilis, Lyngbya lutea, Pseudanabaena sp., Calothrix thermalis, and Fischerella thermalis. Their distribution pattern in relation to physico-chemical parameters of spring water has also been studied. Three cyanobacterial strains of the above mentioned list were grown in culture and their pigment content and nitrogen fixing capacity were also studied. Nitrogen fixing capacities of Calothrix thermalis, Nostoc sp. (isolated in culture) and Fischerella thermalis are 5.14, 0.29, and 2.60 n mole C2H4/µg of Chl-a/hr respectively. Carotenoid : Chlorophyll-a ratio of four mat samples collected from Kharkunda, Suryakunda, Dudhkunda and bathing pool are 2.45, 1.60, 1.48, and 1.34, respectively. Higher value of Carotenoid : Chlorophyll-a ratio coincided with higher temperature.

The role of plant growth regulators on direct and indirect plant regeneration from various organs of Leucaena leucocephala

Prolific differentiation of shoot buds of Leucaena leucocephala was induced from the different plant parts viz. cotyledon, hypocotyl and leaf. Adventitious shoot bud formation was recorded with prudent application of N6-2- (isopentenyl) adenosine and 15% (v/v) coconut water. Coconut water alone was unable to produce any beneficial effect with regard to the shoot bud proliferation but the response was augmented with the increase in concentration of N6-2- (isopentenyl) adenosine. However supra-optimal level of N6-2-(isopentenyl) adenosine was inhibitory. Best response was recorded from the cotyledon explant at 2 mg dm−3 N6-2-(isopentenyl) adenosine compared to the other two explants. Comparative assessment was undertaken following the same experimental protocol in liquid shake culture. The regenerated shoot buds were subcultured in plant growth regulator-free medium where leafy shoot emergence was recorded. Optimum regeneration of roots was observed in these shoots in presence of 1 mg dm−3 α-naphthalene acetic acid. Plantlets were finally hardened following standard procedures before transplantation to the field.In another experimental set up, the de-embryonated cotyledons regenerated shoot buds via callus formation. The regenerated shoots and plantlets obtained through callus mediated organogenesis could be used for rapid multiplication and also for the genetic improvement of individual clones of Leucaena leucocephala.

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.

Characterization of hydrogeochemical process and evaluation of water quality of seven geothermal springs, Bakreswar, India

A study was conducted in seven geothermal springs located in Bakreswar, District Birbhum, West Bengal, India, in order to assess numerous geochemical processes which were responsible for chemical composition of thermal and mineralized water. The study area lies over the Sone, Narmada, and Tapti lineament of Precambrian Chotanagpur Gneissic Complex. Water chemistry has been carried out based on reaction stoichiometry and geo-statistical tools to identify geochemical process. Piper and Gibbs diagram suggest that the spring water belongs to Ca2+-Mg2+-HCO3− + CO32− water type and are controlled by rock dominance. Dissolution and precipitation of calcite, dolomite, gypsum, and fluorite minerals were identified as principle source of major ions in seven geothermal spring water. Principle component analyses revealed that major ions of spring water are derived from geogenic processes such as weathering, dissolution, and precipitation of various minerals. Overall results suggest that major ions of the spring’s water are derived from natural origin because no evidence of anthropogenic sources was observed during the study period. This study has also revealed that water quality of spring’s water is not suitable for drinking purposes and quite suitable for irrigation because of high abundance of Na+, K+, Cl−, and HCO3− ions.