Effect of environmental factors of temperature, salinity and level of heavy metal lead on growth of lead resistant bacterium isolated from Persian Gulf sediments

Heavy metals are one of the most stable contaminants in water and unlike the other contaminants, degrade difficultly, accumulate in food chain and are considered an important threat to general health of humans. The process of biosorption, is a new technology to remove contaminants such as heavy metals based on microorganisms capability. Characterizing lead resistant bacteria in contaminated sediments of Persian Gulf in this study resulted in isolating a Micrococcus sp. as a lead resistant bacterium. Maximum growth of Micrococcus sp. in lead concentration of 50 mg/l, was 0.86 that reduced with increasing lead concentration however, it could grow up to a concentration of 800 mg/l. The optimum temperature was 25 °C for this bacterium and its maximum growth was significantly different in 15°C, 35°C and 45°C (P ≤ 0.05). The results of halophile test also showed that this bacterium is halo tolerant. Bacterial growth increased by increasing salt concentration from 0 to 4% but, when salt concentration reaches to 6, 8 and 10%, it decreased significantly.