Figure 3. The simazine catabolic upper and lower pathways. The catabolic atz gene encoding the respective enzyme is indicated at each metabolic step. Pathways substrates and metabolites: 1. Simazine; 2. Hydroxysimazine; 3. N-etilammelide; 4. Cyanuric acid; 5. Biuret; 6. Allophanate.