Biophysical removal of some toxic heavy metals by Aeromonas strains

Abstract

Some novel approaches have been developed to overcome pollution with the toxic heavy metals as alternatives to physical methods. In this study, bacterial bioremediation using four different recently isolated Aeromonas strains, A. salmonicida, A. piscicola, A. hydrophila, and Aeromonas sp., was applied to overcome pollution with copper sulphate, cadmium sulphate, arsenic oxychloride, and vanadium pentoxide. Aeromonas isolates have been identified by partial sequencing of the 16S rDNA (approx. 1000bp) and subjected to phylogenetic analysis. Aeromonas strains are strongly resistant to high concentration (15mg/l) of the heavy metals under test, Cu, Cd, As and V, with different degrees. Aeromonas sp. strain E4 is less resistant to As and V. Its maximum resistance was till 8 and 10 mg/l to As and V, respectively. Aeromonas salmonicida was capable to remove 90.5%, 49.3% and around 36.7% of 15 mg/l Cu, As, and V solutions, respectively, in a contact time of 4 h under shaking conditions. On the other hand, Aeromonas sp. was promising in removing 86% of Cd solution under the same conditions. Besides, 81.3% of 15 mg/l Cd solution was efficiently removed by Aeromonas hydrophila.