MIXED BACTERIAL CULTURE FOR ATRAZINE DEGRADATION

摘要

The present invention provides a mixed bacterial culture, designated as theculture Atz Mix 1, which originates from the soil exposed to long-termcontamination with atrazine and other s-triazine compounds. The culture AtzMix 1 degrades atrazine at various tempetaures (1O~C to 30~C) in a wide rangeof atrazine concentrations (several ppb to ten thousand ppm), withoutformation of toxic metabolites and leading to the complete atrazinedegradation (mineralization). Atz Mix 1 is a stable mixed culture consistingof at least four members of different morphological, physiological andcatabolic properties. Molecular characterization of the culture Atz Mix 1showed the presence of catabolic genes trzN,atzB, atzC coding the enzymes forthe degradation of atrazine to cyanuric acid and the gene trzD coding theenzymes for subsequent opening of s-triazine ring whereas high degree ofmineralization of ring labelled [14C] atrazine (approximately 80%) confirmedthat the degradation proceeded to yield CO2 and NH4 +. The microbiologicalmethod of degrading atrazine and other s-triazine compounds, which is part ofthe present invention, is advantageous over the so far described methods usingindividual bacterial cultures. This is primarily due to the specific growthand catabolic characteristics of the mixed culture Atz Mix 1 used as abiological agent, i.e. due to its capability to express sustained growth andatrazine- degrading efficiency under the conditions similar to those occurringin atrazine- contaminated environment (e.g. varying temperatures, low C/Nratio, presence of preferential nitrogen source, high atrazineconcentrations). Furthermore, it should be emphasized that the inhibition ofatrazine degradation in the presence of readily accessible nitrogen sourcesobserved with majority of the so far described individual bacterial strainswas not recorded with the culture Atz Mix 1. Accordingly, it can be expectedthat the microbiological method of the present invention will be suitable forremediation of atrazine-contaminated soils, even those rich in nitrogen, aswell as for accelerating the process of atrazine mineralization in wastewaters containing high concentrations of s-triazine compounds.