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Growth and catabolic characteristics of atrazine-degrading community originating from agrochemical factory soil

The present work describes an atrazine-degrading community, designated as Atz Mix 1, which has been enriched from a soil exposed to long-term contamination by atrazine and other s-triazine compounds. A detailed biodegradation study has shown that Atz Mix 1 efficiently degrades atrazine at various temperatures (10º ; C to 30º ; C) in a wide range of concentrations (several ppb to ten thousand ppm), without formation of toxic metabolites. High mineralization degree of ring-labelled [14C] atrazine (approximately 80%) further suggests that the degradation proceeds to the complete mineralization, yielding CO2 and NH4+. PCR assessment of atrazine-degrading genetic potential of the community reveals the presence of catabolic genes trzN, atzB, atzC coding the enzymes for the degradation of atrazine to cyanuric acid and that of the gene trzD coding the enzymes for subsequent opening of s-triazine ring. The present work also describes the microbiological method in which the community Atz Mix 1 has been used as a biological agent. The method is considered advantageous over the so far described methods where individual bacterial cultures have been employed. This is primarily due to the specific and unique growth and catabolic characteristics of Atz Mix 1, i.e. due to its capability to express sustained growth and atrazine-degrading efficiency under the conditions that are similar to those occurring in atrazine-contaminated environment (e.g. low/varying temperatures, carbon limitation, low C/N ratio, presence of preferential nitrogen source, etc) as well as under the conditions that are specific for technological waste waters (high concentration of atrazine and other s-triazine compounds). Accordingly, it can be expected that this microbiological method will be suitable for remediation of atrazine-contaminated soils, even those rich in nitrogen, and for accelerating the process of atrazine mineralization in waste waters containing high concentrations of s-triazine compounds.

atrazine; s-triazine; biodegradation; mineralization; enrichment; contaminated soil; trz; atz

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