Genetically engineered Pseudomonas putida X3 strain and its potential ability to bioremediate soil microcosms contaminated with methyl parathion and cadmium
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A multifunctional Pseudomonas putida X3 strain was successfully engineered by introducing methyl parathion (MP)-degrading gene and enhanced green fluorescent protein (EGFP) gene in P. putida X4 (CCTCC: 209319). In liquid cultures, the engineered X3 strain utilized MP as sole carbon source for growth and degraded 100 mg L−1 of MP within 24 h; however, this strain did not further metabolize p-nitrophenol (PNP), an intermediate metabolite of MP. No discrepancy in minimum inhibitory concentrations (MICs) to cadmium (Cd), copper (Cu), zinc (Zn), and cobalt (Co) was observed between the engineered X3 strain and its host strain. The inoculated X3 strain accelerated MP degradation in different polluted soil microcosms with 100 mg MP kg−1 dry soil and/or 5 mg Cd kg−1 dry soil; MP was completely eliminated within 40 h. However, the presence of Cd in the early stage of remediation slightly delayed MP degradation. The application of X3 strain in Cd-contaminated soil strongly affected the distribution of Cd fractions and immobilized Cd by reducing bioavailable Cd concentrations with lower soluble/exchangeable Cd and organic-bound Cd. The inoculated X3 strain also colonized and proliferated in various contaminated microcosms. Our results suggested that the engineered X3 strain is a potential bioremediation agent showing competitive advantage in complex contaminated environments.
KeywordsGenetically engineered strain Bioremediation Methyl parathion Cadmium
The research was financially supported by the National Natural Science Foundation of China (41230854, 31300102), the National High Technology Research and Development Program of China (“863” Program, 2012AA101402), the Program for Changjiang Scholars and Innovative Research Team in University of China (IRT1247), and the Fundamental Research Funds for the Central Universities (2662015PY016, 2662015PY116).
Compliance with ethical standards
This article does not contain any studies with animals performed by any of the authors. All authors have read and approved the final manuscript.
Conflict of interest
The authors declare that they have no competing interests.
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