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Mixed bacterial culture for degradation of atrazine and other s-triazine compounds in contaminated environments

Background: Although different bacteria have been recognized to successfully degrade s-triazine compounds, the bioremediation methods in which these bacteria are used for cleaning contaminated soils and natural waters have rarely proved efficient1. Objectives: 1. Enrichment of mixed bacterial cultures capable of degrading s-triazine compounds under specific natural conditions. 2. Selection of the most effective culture to be used in bioaugmentation protocols. Methods: Culture enrichment was performed by continuous cultivation in mineral salts medium containing atrazine as the sole C and N source. HPLC method was used for determination of s-triazine compounds and formed intermediates. Radiorespirometric method was applied for evaluation of culture activity in atrazine mineralization. Results: 1. Enrichment experiments resulted in the selection of mixed bacterial culture (Atz Mix 1 NCAIM (P) B 001329 2005-12-091) originating from an agrochemical factory soil. 2. The culture exhibits degrading activity at atrazine concentrations of several ppb to ten thousand ppm and temperatures of 10ºC to 30ºC. 3. Ring-labelled [14C]atrazine mineralization of 78% confirmed culture`s capability to degrade atrazine to CO2 and NH4+. 4. The culture also exhibits sustained growth and atrazine-degrading efficiency under the conditions similar as those occurring in contaminated soils (C limitation, low C/N ratio, presence of preferential N source) and the conditions specific for industrial effluents (high concentrations of s-triazine compounds). Conclusions: 1. Developed innovative bioremediation methods where the culture Atz Mix1 is used as bioaugmentation agent are considered advantageous over the so-far described methods using monocultures. 2. The methods are recommended for cleaning atrazine-contaminated soils and natural waters as well as for treatmant of industrial effluents containing s-triazine compounds. Reference: 1 Mixed bacterial culture for atrazine degradation. WO 2007/0966681 A1.

s-triazine; biodegradation; bacterial culture

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