Mankar; Shilpa, P. and Roychoudhury, K.
Three species of Cyanobacteria namely, Anabaena, Nostoc and Leptolyngbya were grown in BG11 medium supplemented with arsenic salt (250µg/L). The flasks were kept in a static condition with the exposure of light 30-35 µMole of photon m-2s-1and the exposure of period was maintained as light: dark ratio of 14:10 hrs. After seven days incubation, MLSS (mg/L) increased considerably in all three species. The difference in mean arsenic removal between Anabaena and Leptolyngbya is statistically significant and the removal efficiency of Leptolyngbya is much higher in comparison to Anabaena and Nostoc hence, it can be safely concluded that Leptolyngbya is most suitable for removal of arsenic in static culture system.
Keywords: Arsenic | Cyanobacteria | adsorption
Introduction
Arsenic is a toxic metalloid and the compounds containing arsenic are known to cause toxicity to plants, animals and microbes. The primary aim of the present study is to assess the nature of effect, if any, on Cyanobacterial species and the capacity of these species in the removal of arsenic from the system. In the present study three organisms namely, Anabaena, Nostoc and Leptolyngbya were used for arsenic exposure in static culture condition. Although for any commercial application the static culture is not suitable yet, the static culture studies definitely provide the basic data on the different subjects, on the basis of which scale up and the other study can be designed. The Cyanobacterial membrane surface is very good adsorbent system for positive charged metal ions. However arsenic is being a metalloid ion can enter into the cells and get accumulated intracellularly using the transporters of other compounds such as phosphate (Akira Takahashi et al., 2001). The report of arsenic tolerance and removal by Cyanobacterial species require a justification for the use of Cyanobacteria in the management of arsenic. Conventionally there are different techniques available for the management of heavy metals including arsenic. The common technologies available include coagulation, adsorption, ion-exchange, electro-coagulation and biological process (Wickramasinghe, S.R.et al., 2004, Zhang, Y.et al., 2003, Kim J. and Benjamin, M.M., 2004, Kumar P.R.et al., 2004).