Bioremediation Of Atrazine Contaminated Soil

Atrazine has endocrine disruption and potential carcinogenic and teratogenic toxicity to organisms.Long-term and large-scale use has caused serious environmental pollution,but lacks effective treatment methods.The biodegradation method has been widely studied in recent years for the treatment of Atrazine pollution in the environment by virtue of its simple operation,low cost and no secondary pollution.Based on functional microorganisms to control the pollution of atrazine in the soil,the following items were investigated in the present thesis:1.This study isolated and screened a highly efficient degradation strain AT-b3 with Atrazine as the sole nitrogen source from the long-term(3-5 years)soil contaminated with Atrazine in the northeastern region of China(Shenyang).It has a degradation rate of 95% for 100 mg/L of Atrazine within 48 h.By performing morphological observation,physiological and biochemical characterization and 16 SrDNA sequencing and comparison,the degrading bacteria were identified as Enterobacter sp.,and the GenBank accession number was NZ_KI973170.1.2.The effects of cell growth and different environmental conditions(temperature,pH,salinity,culture time and carbon source)on the degradation efficiency of AT-b3 were determined,and the optimal conditions for degradation of Atrazine were investigated by orthogonal experiments.It is clear that the growth of AT-b3 is synchronous with the degradation efficiency of Atrazine.The degradation of Atrazine is best at a temperature of 25-35?,neutral and low salt.The carbon source had little effect on strain and degradation rate,further orthogonal experimental results showed that Atrazine had the best degradation efficiency at 30 °C,pH 7.0 and 0.5% salinity.3.SAGE method was used to screen the genes related to degradation,and 368 differentially expressed genes were obtained,including 231 up-regulated genes and 137 down-regulated genes.The enrichment analysis of gene GO function showed that the genes were mainly enriched in uracil catabolism and nitrogen utilization,nitrate assimilation,hydrogen sulfide biosynthesis,lyase activity and peroxidase activity.Pathway analysis showed that the differential genes involved 70 metabolic pathways,and involved in processes such as nitrogen metabolism,amino acid synthesis and metabolism,ABC transporters,and pyruvate metabolism.4.The degradation products of Atrazine were determined by HPLC-MS.The results showed that hydroxylatrazine,cyanuric acid and urea was detected in the culture after degradation of AT-b3 for 5 days.5.When the bacteriophage was used as the carrier to prepare the repairing agent,the degradation rate of Atrazine was close to 80% at the temperature of 30 °C and repaired for 28 days.In the safety test,the strain can effectively alleviate the damage of Atrazine to sensitive plant(soybeans)and promote the number and activity of microorganisms in the root zone.