Green Global
Foundation   Journal
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A STUDY ON ARSENIC DECONTAMINATING CYANOBACTERIA OF AN ARSENIC AFFECTED SOIL (Pages : 23 - 29)

The present work was undertaken to study the arsenic (As) tolerance limits and decontamination efficiency of some cyanobacteria from an As contaminated soil of Gotera, West Bengal; under laboratory cultural condition. The soil harboured a considerably large number of cyanobacterial cells, 280000 cells g-1 with the dominating species of Genera, Aphanothece (unicellular), Phormidium (non-heterocystous filamentous form), Nostoc, Anabaena, Cylindrospermun and Calothrix (heterocysts bearing filamentous form). In liquid culture condition, most of the cyanobacterial species were able to tolerate 1000 ppm of added As in the form of Na2HAsO4 . However, their tolerance limit to As varied with increasing its concentrations. Only two species viz. Nostoc sp- 1 and Phormidium sp. would be able to survive at 10,000 ppm of As concentration, though in solid culture condition their tolerance limit to As concentration were much less. A Cyanobacterial culture could bioaccumulate about 142.83 ppm of As and influence to volatilization loss was accounted about 937.80 ppm. Inoculation of high concentration As resistant cyanobacteria reduced water-soluble As content both in partially sterilized and non-sterilized soil by about 67% and 50% respectively. Such As decontaminating activity of them were also to be found when they were inoculated in presence of the addition of 250 ppm, 500 ppm and 1000 ppm As to soil. In partially sterilized soil, with added As, such reduction of water soluble As content by their inoculation were about 17.6, 12.7 and 16.7% respectively over control values and that in non sterilized soil were 7.7, 7.0 and 7.7% respectively. The results of this investigation clearly demonstrated that cyanobacteria has high tolerance ability to As concentrations and can able to decontaminate As from liquid culture media as well as from intracellular accumulation and influencing volatilization loss. Download