IMPACT OF HERBICIDES ON THE ABUNDANCE AND STRUCTURE OF INDIGENOUS β-SUBGROUP AMMONIA-OXIDIZER COMMUNITIES IN SOIL MICROCOSMS

摘要

In this study, mixtures of five herbicide-formulated products (atrazine, dicamba, fluometuron, metolachlor, and sulfen- trazone) were applied to soil microcosm columns in increasing concentrations. The toxic impact of herbicides on the indigenous β-subclass Proteobacteria autotrophic ammonia-oxidizer (β-AAO) community was assessed. The β-AAO population abundances were estimated by competitive polymerase chain reaction (PER) targeting the gene amoA, encoding the ct-subunit of ammonia monooxygenase. Community structure was examined by PCR and denaturing gradient gel electrophoresis targeting 16S rDNA with band excision and sequence analysis, and by analysis of amoA gene fragment clone libraries.