Study on possible rehabilitation and recovery of Bandar Emam Region by reducing Nickel and Iron environmental pollutant using microorganisms

Influx of metallic pollutants such as iron and nickel into marine environment has been increased drastically in current era. Due to its harmful effects on living organisms, the aim of current thesis was isolation and identification of microorganisms which could reduce iron and nickel. In order to isolate bacterial strains resistant to iron and nickel, deposit samples were collected from five stations in Imam Khomeini Port cultured on BHI agar medium containing 1000 ppm of iron and 50 ppm of nickel and incubated for 24 hours in 30 oC. Endurance threshold of strains isolated to different concentrations of iron (1000- 15000 ppm) and nickel (100- 25000 ppm) in BHI broth medium were evaluated, the most resistant strains were selected and MIC and MBC were determined. Growth curve of selected strains in the presence and absence of iron and nickel were assessed by turbidity method. Along with above mentioned process, removal amount of metal by living cells and dead biomasses of selected strains were assessed by atomic absorption analysis and then 16S rRNA method was used to identify and approve the selected strains. Results of the current study were demonstrated that among of 16 and 12 resistant strains to nickel and iron, two selected strains (number16 and 7) as the most resistant strains had MIC and MBC (29800 and 29700) and (26300 and 26500), respectively. It should be mentioned that iron’s MIC was not assessable. Results of atomic absorption analysis was demonstrated that the highest amount of nickel reduction in a medium with concentration of 194 ppm and 71 ppm were 16.7% and 63% after 72 hours by selected strain number 16 respectively and in a medium containing 158 ppm iron, after 50 hours 8.4% by selected strain 7, while dead biomass of strain 16 reduced nickel to the amount of 40.6% and it reduced 21% and 4% of iron in solutions with 46 ppm and 792 ppm of iron. Results of molecular analysis demonstrated that strain 16 was Bacillus subtilis. In addition, Bacillus subtilis which has been isolated in this study with ability of nickel and iron removal is an appropriate candidate to be used in aquatic environments.