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Studies on development of Cr6+ resistant strain of Pseudomonas aeruginosa for improved Cr6+ biosorption: Scanning Electron Microscopic and spectrophotometric studies
Author : Subhra Das, A. K. Banik and Asim K. De*
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ABSTRACT
Hexavalent chromium (Cr6+) is one of the most potent heavy metal pollutants released from various industries into water bodies. Most commonly used physico-chemical methods for removal of Cr6+ from wastewater are inefficient, expensive and produce unmanageable toxic sludge. Recent studies showed that biosorption based on metal-biomass interaction can be an alternative to commonly employed methods for Cr6+ removal from wastewater. In this study four types of bacteria such as Escherichia coli, Bacillus pumilus, Bacillus subtilis and Pseudomonas aeruginosa were screened for high Cr6+ concentration tolerant strain isolation. It was found that Escherichia coli and Bacillus pumilus are resistant to 250 ppm and Bacillus subtilis resistant to 350 ppm and Pseudomonas aeruginosa can resist upto 500 ppm of initial Cr6+ concentration. Scanning Electron Microscope studies of mycelia of parent cells of Pseudomonas aeruginosa, and Cr6+ resistant cells of Pseudomonas aeruginosa revealed that high Cr6+ concentration of resistant strain induces some morphological changes. Metalbiomass interaction was confirmed by Fourier Transform Infra-Red (FTIR) spectroscopic study which also indicates the presence of hydroxyl amine, amide, carbonyl and carboxyl groups in cells wall of Pseudomonas aeruginosa. EDX analysis also showed that the parent Pseudomonas aeruginosa does not contain Cr6+ but the Cr6+ resistant Pseudomonas aeruginosa contains chromium along with carbon, oxygen and platinum.
KEYWORD
Hexavalent chromium, biosorption, resistance, Pseudomonas aeruginosa, EDX spectra