Phytoextraction and biodegradation of atrazine by Myriophyllum spicatum and evaluation of bacterial communities involved in atrazine degradation in lake sediment

摘要

The accumulation of atrazine in lake sediments leads to persistent contamination, which may damage the succeeding submerged plants and create potential threats to the lake eco-environment. In this study, the degradation characteristics of atrazine and its detoxication byMyriophyllum spicatumand the associated bacterial community in lake sediments were evaluated.M. spicatumabsorbed more than 18-fold the amount of atrazine in sediments and degraded atrazine to hydroxyatrazine (HA), deelthylatrazine (DEA), didealkylatrazine (DDA), cyanuric acid (CYA) and biuret. The formation of biuret suggested for the first time, the ring opening of atrazine in an aquatic plant. The residual rate of atrazine was 6.5 ± 2.0% inM. spicatum-grown sediment, which was significantly lower than the 18.0 ± 2.5% in unplanted sediments on day 60 (P < 0.05). Moreover, on day 15, the increase in contents of HA, CYA and biuret inM. spicatum-grown sediment indicated thatM. spicatumpromoted the degradation and removal of atrazine following rapid dechlorination. The colonization ofM. spicatumand the addition of atrazine altered the structure of the dominant bacterial community in sediments, including effects onNitrospiraeandAcidobacteria. Based on the maximum amount among the genera of atrazine-degrading bacteria,Acetobacterwas most likely responsible for the degradation of atrazine. Our findings reveal the natural attenuation of atrazine by aquatic organisms.