Anindita Chakraborty

Bio: Anindita Chakraborty is an academic researcher. The author has contributed to research in topics: Homologous recombination & DNA polymerase. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Radiation Induced DNA Double Strand Break Studies of a Metal Sensitive Novel Bacterial Isolate from East Calcutta Wetland

Abstract: Problem statement: This study was an attempt to isolate anaerobic microbes with potential for DNA double strand break repair using methanogen specific medium (DSMZ 120) from East Calcutta Wetland in India. It also intended to verify the specificity of the medium for isolation of the desired family of microbe. Approach: Culture based technique was used to obtain the pure isolate that was further characterized in details. For double strand break repair studies, isolate was irradiated with different doses of 60Co gamma rays and its subsequent repair was observed using pulse field gel electrophoresis and asymmetric field inversion gel electrophoresis. Inhibitor was used to predict the mechanism of repair. Results: In this study we isolated and characterized a metal sensitive anaerobic microbial strain obtained using methanogen specific medium (DSMZ 120) from East Calcutta Wetland in India. The strain was one of the members of the group of uncultivated bacterium as evident from phylogenetic analysis, thus indicating the successful cultivation of an as yet uncultivable novel microbe (GenBank Acc. No. FJ 930097) and also the non-specific growth of microbes in prescribed medium. It was a Gram positive Bacilli, member of Fermicutes with optimum growth at 25°C and pH-7. The growth curve analysis showed a lag phase up to 24 h, log phase from 24-48 h, an early stationary phase from 96 h onwards. The strain could repair the DNA double strand break caused by irradiation with 60Co γ rays. The dose profile study revealed maximum repair at 60 Grays and thereafter a drop in repair ability with increase in irradiation dose. The time required for repair showed an essential incubation period of 4 h. The DNA polymerase inhibitor, Arabinose CTP inhibited the repair indicating the involvement of polymerase in the repair process and thus pointing towards homologous recombination as the underlying mechanism. Conclusion: In this study we were able to cultivate an as yet uncultivable anaerobic bacterial isolate and predict the growth conditions for the isolate. On irradiation with 60Co γ rays the isolate showed maximum repair following 60 Gray damage. DNA polymerase inhibitor arabinose CTP inhibited the repair mechanism completely. This indicated that DNA polymerase took active part in repair process and thus the mechanism was that of homologous recombination repair.

East Kolkata Wetland: A Multifunctional Niche of International Importance

Abstract: Problem statement: In the megacity Kolkata, the need for space to acco modate the ever increasing population is increasing day by day. As a result the encoarchment of the large wetland on the eastern frindge of the city is increasing and s o is the threat of its loosing the status of Ramsar Status. Approach: Proper documentation of the existing traditional p ractice with sound scientific basis and the direct as well as indirect benefit that the city receives as a result of its existance could b e an approach towards its conservation. Results: East Kolkata Wetland (EKW) is a unique example of a wetland ecosystem involved in both resource recover y and environmental protection and in the process providing a stable urban fringe to an expanding met ropolis. It ensures economic benefit and employment generation because of resource recovery activities based on utilization of the city's sewage. It acts as a sink for city sewage and garba ge, even at times a little flow of industrial efflu ents with toxic heavy metals as well as hazardous contaminants like sulphate and nitrate to name a few. The purification process operating there depends to a l arge extent on the activity of the diverse microbia l population using liberal sunshine. On trying to und erstand the microbial flora, a rich diversity of th e bacterial domain was revealed with immense potential for commercial application. The extracellular enzymes from microbial origin of EKW were used for detergent formulation, dehairing of hide at neutral pH, silver recovery from exposed X-ray film s and so on. The microbes themselves could entrap metals inside them as nanoparticles, remove sulphat e from solution and prevent nitrate mediated eutrophication. The soluble waste from the megacity goes through various rounds of purification in the waste water fisheries, called Bheri in local parlance before being used for agricultur e. This in turn results in fish production and purification of the waste wa ter up to 99% in terms of faecal coliform count and to a large extent for other parameters. The metal conten t in the muscles of the surface feeder and bottom feeder fishes were comparable to that of the same v ariety from rain water fed ponds, indicating safe u se of the waste water. The agriculture using waste wat er mostly produces paddy and vegetables. The green leafy vegetables produced from EKW when compared with same variety from non-EKW were found to be healthy without any additional unwanted metal accumulation. The entire resource recovery process was relatively safe, ecofriendly as well as economi cal. Conclusion/Recommendations: Thus EKW purifies the waste of a large part of the city, gen erates edible resources, provides employment, houses diverse flora and fauna and also harbours a rich re pertoire of microbes with immense potential for application. The objective of the present review is to emphasize the need of its conservation and also intensify the research on the microbial diversity i n these wetlands.