To investigate the optimum growth conditions and screen atrazine-degrading strains,two atrazine-degrading strains named Z9 and Z42 were isolated from black earth in a cold area with a long-term application of atrazine by standard enrichment techniques.Z9 utilizes atrazine as both the nitrogen and carbon source whereas Z42 utilizes atrazine as the sole nitrogen source to grow.The atrazine degradation rates of the two strains reached 77.7%and 65.6%,respectively after 14 days culture in a liquid medium with an atrazine concentration of 100 mg/L.Z9 and Z42 were identified as Microbacterium sp.and Arthrobacter sp.The optimum inoculation amount and rotation speed for Z9 and Z42 to grow and degrade atrazine are 3%and 120 r/min respectively.
