Mapping atrazine and phenol degradation genes in Pseudomonas sp. EGD-AKN5

• Lab isolate Pseudomonas sp. EGD-AKN5 has multi-substrate degrading capacity.
• Atrazine degradation occurs via action of atzABCDEF genes.
• Multicomponent phenol hydroxylase present in lab isolate.
• Catechol biodegradation follows the ortho cleavage pathway.
• The isolate has potential for bioremediation of contaminated soil.

Bacterial isolates with multi-substrate degradation capacities are good candidates for bioremediation of environmental niches. Lab isolate Pseudomonas sp. EGD-AKN5 was found to degrade atrazine, benzoate, phenol, toluene and catechol at the rate of 1.88 ± 0.01, 16.5 ± 1.37, 9.08 ± 2.20, 3.86 ± 0.11, and 3.3 ± 0.29 mg L−1 h−1, respectively. Draft genome sequence analysis demonstrated the presence of the complete degradation pathway for atrazine and phenol. Gene annotation results indicated that atrazine was degraded via the chlorohydrolase route with atzA/B/C/D/E/F genes, while phenol was converted to catechol via a multicomponent phenol hydroxylase from the phc pathway. Genes from the ortho pathway were responsible for the further biodegradation of catechol; a result that was confirmed by enzyme assays. A model to describe the growth and biodegradation of atrazine, phenol and related compounds was applied and fit to a series of aerobic batch degradation experiments. Kinetic studies revealed that EGD-AKN5 showed potential to degrade both phenol and atrazine simultaneously using phenol as the carbon source and atrazine as nitrogen source. Gene expression studies indicated a longer lag phase for expression of genes from the atrazine degradation pathway, when compared to expression of phenol and catechol degradation.