Isolation and Characterization of Atrazine-degrading Strains and Biotreatment Experiment of Industrial Wastewater

Abstract:

By using enrichment culture in liquid minimal medium or direct culture on minimal medium plates, thirteen bacterial strains (AD27-AD39) capable of utilizing atrazine as a sole nitrogen source for growth were isolated from a mixture of industrial wastewater and sludge from an atrazine manufacturing plant. Based on 16S rRNA gene sequencing, eleven strains were identified as Arthrobacter spp. and two strans were identified as Pseudomonas spp.. We further studied in detail the composition of atrazine-degrading genes and degradation characteristics of Arthrobacter sp. AD30 and Pseudomonas sp. AD39 that have high degradative activity. From PCR assays, it was indicated that both AD30 and AD39 strains contained atrazine-degrading genes trzN and atzBC and was capable of degrading toxic atrazine to nontoxic cyanuric acid. The biodegradation experiments showed that the percentage of atrazine removal were 92.5%, 97.9% and 99.6% respectively after AD30, AD39 or the mixture of the two strains were inoculated and incubated at 30°C for 48 hours in minimal media containing 200 mg/L atrazine, indicating that atrazine degradation by the mixed bacteria was more effective than the single strain. In addition, after industrial wastewater containing 176 mg/L atrazine was inoculated with the mixed bacteria and incubated at 30°C with shaking for 72 hours atrazine were removed by 99.1%, implicating that the mixed bacteria are good candidate for biotreatment of atrazine-containing industrial wastewater.