Biodegradability and ecological safety assessment of Stenotrophomonas sp. DDT-1 in the DDT-contaminated soil

Abstract

The biodegradability and ecological safety assessment of the previously isolated DDT-degrading bacterial strain Stenotrophomonas sp. DDT-1 were investigated in the DDT-contaminated soil under laboratory and field conditions. Under laboratory conditions, the degradation rates of fresh p,p′-DDT in soil were enhanced by 2.0–3.0-fold with the introduction of the strain DDT-1 compared to those of the control treatments. A similar enhancement in the dissipation of DDTs (p,p′-DDT, p,p′-DDE, p,p′-DDD, and o,p′-DDT) in the aged DDT-contaminated field plot soils resulted from the inoculation with this strain. Meanwhile, the degradation rates of DDTs increased by 2.9–5.5- and 2.8–7.6-fold in the inoculated greenhouse and open field soils, respectively, after field demonstration application of strain DDT-1 preparation. Moreover, no significant differences in the soil enzyme activity, microbial functional diversity, and bacterial community structure were observed between the inoculated and un-inoculated field soils, but several soil microbial genera exhibited some fluctuations in abundance. It is concluded that strain DDT-1 could accelerate the removal of DDTs residues in field soils, and furthermore, its inoculation was ecologically safe.