Characterization of a marine-isolated mercury-resistant Pseudomonas putida strain SP1 and its potential application in marine mercury reduction
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The Pseudomonas putida strain SP1 was isolated from marine environment and was found to be resistant to 280 μM HgCl2. SP1 was also highly resistant to other metals, including CdCl2, CoCl2, CrCl3, CuCl2, PbCl2, and ZnSO4, and the antibiotics ampicillin (Ap), kanamycin (Kn), chloramphenicol (Cm), and tetracycline (Tc). mer operon, possessed by most mercury-resistant bacteria, and other diverse types of resistant determinants were all located on the bacterial chromosome. Cold vapor atomic absorption spectrometry and a volatilization test indicated that the isolated P. putida SP1 was able to volatilize almost 100% of the total mercury it was exposed to and could potentially be used for bioremediation in marine environments. The optimal pH for the growth of P. putida SP1 in the presence of HgCl2 and the removal of HgCl2 by P. putida SP1 was between 8.0 and 9.0, whereas the optimal pH for the expression of merA, the mercuric reductase enzyme in mer operon that reduces reactive Hg2+ to volatile and relatively inert monoatomic Hg0 vapor, was around 5.0. LD50 of P. putida SP1 to flounder and turbot was 1.5 × 109 CFU. Biofilm developed by P. putida SP1 was 1- to 3-fold lower than biofilm developed by an aquatic pathogen Pseudomonas fluorescens TSS. The results of this study indicate that P. putida SP1 is a low virulence strain that can potentially be applied in the bioremediation of HgCl2 contamination over a broad range of pH.
KeywordsPseudomonas putida Marine environment mer operon Bioremediation of HgCl2 contamination
We sincerely thank Dr. L. Sun of the Institute of Oceanology, Chinese Academy of Sciences and her laboratory for kind help in providing the bacterial strain P. fluorescens TSS. This work was financially supported by Innovation Projects of the Chinese Academy of Sciences grant KZCX2-EW-206 and KZCX2-YW-Q07-04, the National Natural Science Foundation of China (NSFC) grant 20975089, and the 100 Talents Program of the Chinese Academy of Sciences.
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