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.