Zn-dependent enhancement of Atrazine biodegradation by Klebsiella variicola FH-1.

Degradation efficiency of Atrazine by Klebsiella variicola FH-1 is improved by the addition of Zn. Both the chromosome and plasmid genomes of strain FH-1 were sequenced and annotated to identify genes involved in the degradation of Atrazine. Four open reading frames (ORFs) 1040, 2582, 3597, and 4043 encoding Zn-dependent hydrolases were knocked out to verify their predicted functions in the degradation of Atrazine. In the presence of Zn, the biodegradation efficiency of Atrazine by knockout mutant ∆ORF 3597 was 13.7% lower than that of wild type (WT) of strain FH-1 but still 9.4% higher than that of WT without Zn. These results indicated that ORF 3597 played a synergistic role but may not be the sole factor involved in the degradation of Atrazine. The enzymatic activities of pydC encoded by ORF 3597 were further characterized in the degradation of Atrazine. Results of fluorescence staining and flow cytometry analyses showed that the survival of bacterial cells and cell membrane permeability were increased in the presence of Zn at different concentrations. Our study provided a scientific foundation for further investigation of the biological mechanisms of improving the degradation of Atrazine by strain FH-1 with the presence of Zn.