Nicosulfuron on the Atrazine-degrading Arthrobacter sp. DNS10 by assays of intracellular accumulation of substrates, Zeta potential, EPS, and stress responses

Abstract

Atrazine is often formulated with nicosulfuron as a commercial herbicide to enhance the weed control effect, however, the effect of nicosulfuron on the degradation of atrazine-degrading strain Arthrobacter sp. DNS10 was still unclear. In this study, the accumulation of atrazine in Arthrobacter sp. DNS10, as well as the cell surface characteristics (Zeta potential and extracellular polymers constitution) and antioxidant enzyme activity at different concentrations of nicosulfuron exposure for 48 h were measured. The results showed that the quantity of atrazine accumulation in strain DNS10 and the Zeta potential on strain cell surface were increased when nicosulfuron exposure level was increased. Three-dimensional fluorescence spectrum analysis found that nicosulfuron exposure could quench the peaks which represent the aromatic protein substances and soluble microbial metabolites in EPS of strain DNS10 In addition, the co-existed nicosulfuron could positively induce the activity of antioxidant enzymes (SOD and CAT) and malondialdehyde content, and also induce cell damage. This work proposes the mechanism by which nicosulfuron inhibits the biodegradation of atrazine, which is of great significance for improving the bioremediation of mixed herbicide contamination.