Genetic potential,diversity and activity of an atrazine-degrading community enriched from a herbicide factory effluent

Aims: To characterize an atrazine-degrading bacterial community enriched from the wastewater of a herbicide factory. Methods and Results: The community mineralized 81·4 ± 1·9% of ¹⁴C-ring]atrazine and 31·0 ± 1·8% of ¹⁴C-ethyl]atrazine within 6 days of batch cultivation in mineral salts medium containing atrazine as the sole nitrogen source. Degradation activity of the community towards different chloro- and methylthio-substituted s-triazine compounds was also demonstrated. Restriction analysis of amplified 16S rDNA revealed high diversity of bacterial populations forming the community, with Pseudomonas species dominating in the clone library. Atrazine-degrading genetic potential of the community determined by PCR revealed the presence of trzN, atzB, atzC and trzD genes. The trzN, atzB and atzC genes were shown to be located on a plasmid of 322 kb. Quantitative PCR showed that relative abundances of atzB, atzC and trzD genes were approx. 100-fold lower than 16S rDNA. Conclusions: The enriched community represents a complex bacterial association expressing substantial atrazine-mineralizing activity and a broad specificity towards a range of s-triazine compounds. Significance and Impact of the Study: Our study is beginning to yield insights into the richness, genetic potential and density of functional atrazine-mineralizing community that could be a potential bioaugmentation agent for improving biotransformation processes in wastewaters bearing different s-triazine compounds.