Genetic and physiological diversity among atrazine-degrading bacteria isolated from industrial wastewater

Abstract:

[Objective] The purpose of this paper is to reveal the genetic and physiological diversity of atrazine-degrading bacteria isolated from industrial wastewater, to provide new insights for molecular mechanism of atrazine biodegradation. [Methods] Atrazine-degrading genes of 27 atrazine-degrading strains were detected by the conventional PCR and their composition of atrazine-degrading genes was analyzed. The genome composition of these bacteria was analyzed by repetitive extragenic palindromic PCR (rep-PCR) genomic fingerprinting. Triazine hydrolase TrzN in bacteria, the first enzyme for atrazine-degrading pathway, was detected by Western blot analysis. Nitrogen source (atrazine, ametryn, atratone, cyanazine, prometryn, simazine and cyanuric acid) and carbon source (glucose, sucrose, maltose, lactose, sodium citrate, sodium succinate and sodium acetate) used by these bacteria were analyzed by measuring absorbance of the culture at 600 nm. [Results] The conventional PCR experiments indicated that three main atrazine-degrading gene combinations (i) trzN-atzBC, (ii) trzN-atzABC, and (iii) atzADEF were observed respectively from either strain of 27 atrazine-degrading strains. rep-PCR analysis indicated that these bacteria could be differentiated into 7 clusters. Western blot analysis proved that 24 strains contained TrzN protein. Nitrogen source experiments showed that two strains could use all of the 7 compounds as nitrogen source and other 25 strains only could use 2?6 compounds as nitrogen source. Carbon source experiments showed that 10 strains could use all of the 7 compounds as carbon source and other 17 strains only could use 3?6 comlounds as nitrogen source. [Conclusion] These 27 atrazine-degrading strains isolated from industrial wastewater have their genetic and physiological diversity.