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Potential ecological risks of thermal-treated waste recombination DNA discharged into an aquatic environment

Fu, Xiao H., Wang, Lei, Li, Meng N., Zeng, Xiao F., Le, Yi Q.
Journal of environmental science and health 2011 v.46 no.14 pp. 1640-1647
EDTA (chelating agent), aquatic environment, genes, ionic strength, pH, plasmids, pollution, recombinant DNA, risk, sodium chloride
It has been shown that thermal-treatment at 100°C can denature deoxyribonucleic acid (DNA), yet this does not cause it to break down completely. To clarify the risk of gene pollution from thermal-treated recombinant DNA, the renaturation characteristics of thermal-denatured plasmid pET-28b and its persistence in aquatic environments were investigated. The results revealed that the double-stranded structure and transforming activity of the thermal-treated plasmid DNA could be recovered even if the thermal-treatment was conducted at 120°C. The presence of sodiumchloride (NaCl) and ethylenediamine tetraacetic acid (EDTA) led to the increase of renaturation efficiency of the denatured DNA. When thermal-treated plasmid DNA was discharged into simulated aquatic environments with pH values from 5 to 9, it showed a longer persistence at pH 7 and 8 than that at 5, 6 and 9; however, the denatured plasmid DNA could persist for more than 33 min at any pH. Moreover, a higher ionic strength further protected the thermal-denatured plasmids from degradation in the simulated aquatic environment. These results indicated that when the thermal-treated DNA was discharged into an aquatic environment, it might not break down completely in a short period. Therefore, there is the potential for the discarded DNA to renature and transform, which might result in gene pollution.