Study of Heavy metal uptake by Bacillus sp and E. coli

Abstract

Background: Over the past century, unrestricted mining, extensive industrialization, modern agricultural practices and faulty
waste disposal methods have resulted in the release of unprecedented levels of toxic heavy metals like Cd, Hg, Ag, Sn, Pb, Cu, Co,
Mn, Zn, etc into the environment. Many metals are essential for microbial growth in less concentration, yet are toxic in higher
concentrations. Various methods are available for the removal and management of heavy metals: Conventional physico-chemical
methods and emerging biosorption methods. Biosorption is an attractive alternative approach which involves the binding or
adsorption of heavy metals to living or dead cells. Many microbes have the ability to selectively accumulate metals. Aim: The
present study was intended to analyze the uptake systems of Bacillus and E. coli against different concentration of heavy metals
like Zn, Cu, Cd, and Hg in their salt form incorporated into nutrient broth medium observed over a regular interval of time.
Methodology: Analysis was based on how much of the metal from the original concentration used was left behind in the media
after the rest being up taken by the organism. This was done using Atomic Absorption Spectrophotometry (AAS) which was
indirectly the representation of percent uptake of heavy metal by the respective organism. Results: The study showed that Gram –
ve organisms like E.coli exhibited more resistance to metals like Zn, Cu and Hg in relative comparison with Gram +ve organisms
like Bacillus. Conclusion: Bacillus sps was less sensitive to effect of Cd than in E. coli