engleski

Diversity and activity of atrazine-degrading community enriched from agrochemical factory soil

Bacterial community enriched from an agrochemical factory soil exposed to long-term contamination by atrazine and other s-triazine compounds was characterized with respect to its catabolic activity, diversity and genetic potential. This community mineralized cca 71% of [14C-ring] atrazine and 57% of [14C-ethyl] atrazine within 4 days of batch cultivation in mineral salts medium containing atrazine as the only N source. Degradation activity of the community toward different s-triazine compounds was also demonstrated. Restriction fragment length polymorphism (RFLP) analysis of the 16S rRNA clone library revealed high diversity of bacterial populations forming the community. The analyzed cloned sequences clustered within the Proteobacteria, the Actinobacteria, Bacteroidetes and Firmicutes. Dominant RFLP families were related to Pseudomonas, Flavobacterium, Paenibacillus and Arthrobacter species. Plate cultivation analysis showed that community consisted of four culturable members, possessing catabolic activities. Two of them, Arthrobacter sp. ATZ1 and Arthrobacter sp. ATZ2, are involved in the upper pathway, while Ochrobactrum sp. CA1 and Pseudomonas sp. CA2, are involved in the lower pathway of atrazine degradation [1]. Plasmid profiles and Southern blot analyses revealed that in the community member ATZ2, the trzN, atzB, atzC genes and insertion sequence IS1071 were located on 190-kb plasmid. The trzD gene and IS1071 were detected on 355-kb plasmid in the community members CA1 and CA2, while the location of atzA remained unknown. Quantitative PCR showed that the abundances of atzBC genes relative to 16S rRNA were 0.4 and 0.8%, respectively, while the abundance of trzD gene was 0.04%. The relative abundance of atzA gene was approx. 100-fold lower than that of trzD. The enriched community represents a complex bacterial association expressing substantial atrazine-mineralizing activity and a broad specificity toward a range of s-triazine compounds. The obtained results also suggested that, in addition to plasmid conjugation, IS could play a role in dispersing atrazine-catabolic genes within soil microbiota.

atrazine; biodegradation; bacterial community; diversity; atz genes; trz genes.

nije evidentirano