Microbial bioremediation and characterization of Arsenic resistant bacteria

Arsenic is a toxic metalloid existing everywhere in the nature. It is toxic to most organisms and considered as human carcinogen. Arsenic contamination leads to severe health problems with diseases like damage of skin, lung, bladder, liver and kidney as well as central nervous system. As arsenic can be found everywhere in nature it may come in contact with food chain very easily through either water or cultivated crops. My thesis works include studies of bioremediation of arsenic by microorganisms. In this experiment the test organisms were collected from the Hazaribagh tanning industrial area of Dhaka, Bangladesh. The whole laboratory works were performed with two types of bacterial strains. Genomic DNA isolation and restriction digestion of genomic DNA, plasmid DNA isolation, Growth response to different concentrations of Arsenic, minimum inhibitory concentration (MIC), plasmid degradation procedures were carried out during this experiment. The MIC value for amoxicillin of these test organisms was 300 μg/ml and they are able to degrade 5 mM arsenite (AsIII) and 40 mM arsenate (AsV). Though the experiment was carried out with two bacterial strains but by observing all experimental data such as restriction digestion, growth response to the arsenic before and after treated with ethidium bromide and minimum inhibitory concentration it can be concluded that these two strains were not different. These bacteria are able to survive in high concentration of antibiotics and arsenic (AsV and AsIII). Loss of plasmid resulted no growth on media containing arsenic. These results support that plasmid contains important genes that are responsible for surviving bacteria in stress conditions