Enhancing iron oxidation efficiency by a native strain of Acidithiobacillus ferrooxidans via response surface methodology, and characterization of proteins involved in metal resistance by proteomic approach

Abstract

The effects of different factors on growth and bio-oxidation efficiency of a native strain of <em>Acidithiobacillus ferrooxidans</em> have been evaluated by the utilization of response surface methodology, RSM. Medium pH and iron concentration were found to be the most significant factors while temperature and ammonia concentrations had the least weight within the ranges investigated. Optimum operational conditions for maximizing Fe²⁺ oxidation were found to be 31 ^oC, 7 g/Liron concentration, 4.5 g/Ltotal ammonium salt concentration and medium pH 1.85. Maximum recovery of 98% of Zinc is the main outcome of results as observed at 7 g/Lof Fe²⁺, under optimized experimental conditions. The response of a bacterial strain to metals toxicity also studied. The isolate showed good resistance to most of the toxic metals. The proteomics approach was used to identify the differentially expressed proteins under heavy metal stress. Four of the differentially expressed proteins were identified as major outer membrane protein of <em>A. ferrooxidans</em>, ribulose large bisphosphate carboxylase subunit<em>, </em>and holo synthase.