Changes in Pseudomonas sp. CY growth in the presence of atrazine

Abstract

Microbial degradation, compared with many other degradation processes, is the most important pathway for the depletion of triazine herbicides in soil. The aim of this study was to determine the growth potential of Pseudomonas sp. CY in the presence of atrazine and additional carbon (sodium citrate) and nitrogen (ammonium-nitrate) sources. The experiment was performed with five treatments: i) 100 mg/L atrazine (control); ii) One hundred mg/L atrazine + sodium citrate (0.3 %,w/v); iii) One hundred mg/L atrazine + sodium citrate (0.3 %, w/v) + ammonium nitrate (0.6 %, w/v);iv) Atrazine (300 mg/L) + sodium citrate (0.3 %, w/v) and v) Atrazine (500 mg/L) + sodium citrate (0.3 %, w/v). The bacterial count was determined after incubation (7 days at 30°C) using the agar plate method, while atrazine degradation was determined by measuring the optical density at 221 nm. Pseudomonas sp. CY can partially utilize atrazine as the sole source of carbon and energy. The highest values of the bacterial count were determined at the highest initial atrazine concentrations; however, bacterial growth was not detected in these treatments. A significant impact of citrate on bacterial growth and atrazine degradation was observed, while the addition of nitrate decreased the atrazine degradation rate. This study confirmed that Pseudomonas sp. CY can be used as a prominent candidate for the remediation of atrazine-affected environments.