Metal Tolerance and Biosorption Potential of Bacillus pumilus

• Poll Res 29(2): 351-357 (2010)

• Aji M. Thomson and G. Muraleedhara Kurup
  

• E Mail: gmuraleedhara_kurup@rediffmail.com

• Abstract: Contamination of environment with toxic heavy metals is a significant problem. Conventional techniques applied to remove heavy metals from polluted water are ineffective for dilute or low concentration metal ions. For this reason, the examination of effective and innovative method becomes an important need. Biosorption process, using microbial biomass as a biosorbent has gained great attention. After a preliminary screening the most suitable bacteria for an application, which is resistant to copper, zinc and iron was isolated from the metal contaminated soil. Metal tolerance in terms of growth rate and minimum inhibitory concentration (MIC) was investigated. The adsorption isotherms obtained experimentally obeyed the Freundlich Langmuir adsorption isotherm model. Maximum adsorption levels according to the Langmuir adsorption models were 2.94mg/gm for copper, 1.07 mg/gm for zinc and 1.34mg/gm for iron. Biosorption was found to be higher at lower metal concentration as compared to higher concentration. The main parameters influencing biosorption namely pH and contact time had been examined. The adsorption kinetic experiments indicated that a contact period of 30 minutes was sufficient to attain equilibrium. The optimum pH for Bacillus pumilus was between pH 4 and 5for iron, and between 5 and 7 for Copper. The bacteria was able to remove 75%of copper, 76% of iron and 70% zinc out of the solution under optimum conditions. The results suggested that Bacillus pumilus may find promising application for removal of copper, zinc and iron ions from contaminated aqueous systems.