Sulfate reducing bacteria (SRB) was isolated from marine sediment of Sidi Kerir, Alexandria and selected according to its high tolerance to different heavy metals (Cd2+, Pb2+ and Hg2+), Zn2+ and Cu2+ ions showed high inhibitory effect on the SRB. The results showed that more resistance towards these examined heavy metals was achieved on adjusting the culture medium of SRB at pH 7 and 30˚C and it depends on the type of metal. The minimum inhibitory concentration (MIC) of each heavy metal was determined and the SRB heavy metal tolerance showed a descending order from Hg2+ , Pb2+ , Cd2 , Zn2+ then +Cu2+ ions. Moreover, the tested metals affected the specific growth rate and the total cell protein of the SRB. The obtained results indicated that marine SRB has a high tolerance level (500µM) towards the most toxic heavy metals (Hg2+ and Cd2+ ions) and it is promising to be used in removing not only mercury but also cadmium ions from marine environments.
Key words: SRB, heavy metal, tolerance, marine, Hg2+, Cu2+.
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