engleski

Mixed bacterial culture for remediation of s-triazine contaminated environment and treatment of industrial effluents

The present work describes a mixed bacterial culture of natural origin deposited as the culture Atz Mix 1 in the National Collection of Agricultural and Industrial Microorganisms, Budapest, Hungary under the number NCAIM (P) B 001329 2005-12-09[1]. The culture was enriched from an agrochemical factory soil exposed to long-term contamination by atrazine and other s-triazine compounds. Growth kinetics and biodegradation studies have shown that Atz Mix 1 exhibits sustained growth and efficiently degrades atrazine at various temperatures (10º ; C to 30º ; C) in a wide variety of concentrations (several ppb to ten thousand ppm), without formation of toxic metabolites. High mineralization degree of ring-labelled [14C] atrazine (approximately 80%) further shows that atrazine degradation proceeds to the complete mineralization, yielding CO2 and NH4+. PCR assessment of the culture genetic potential reveals the presence of catabolic genes trzN, atzB, atzC coding the enzymes for the degradation of atrazine to cyanuric acid and the gene trzD coding the enzymes for subsequent opening of s-triazine ring. The present work also describes a biodegradation method in which the culture 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 are 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 industrial effluents (high concentration of atrazine and other s-triazine compounds). Accordingly, it can be expected that this method will be suitable for bioremediation of atrazine-contaminated soils, even those rich in nitrogen, and for accelerating the process of atrazine mineralization in contaminated natural waters and industrial effluents.

atrazin; agrochemical factory soil; biodegradation; trz; atz

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