Environmental Behavior of Ametryne and Its Influences on the Soil Microbial Community Diversity / Comportamento ambiental da ametrina e suas influências sobre a diversidade da comunidade microbiana dos solos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The herbicide ametryne is relatively persistent in the environment and is among the five most used in the sugarcane crop in Brazil. Radiometric and molecular techniques were applied in this study to evaluate sorption/desorption and biodegradation of ametryne and the impact caused its residence time on the structure and diversity of the soil microbial community, respectively. The soils were collected from forested areas, with no history of ametryne application. One of them showed a clayey (NVef) and the other one a sandy (RQo) texture. Ametryne presented low to moderate sorption potential (Kd = 2.2 e 9.9 L kg-1 in the RQo and NVef soils, respectively). In parallel, the biodegradation rate (t1/2 = 16 and 36 days in the NVef and RQo, respectively) and the formation of soil bound residues of 14C-ametryne in soil (59 and 38 % of applied amount in the NVef and RQo, respectively) were much greater in NVef soil, showing its higher dissipation rate. There was also formation of a metabolite of environmental importance, which corresponded to 19 and 26 % of applied amount in the RQo and NVef soils, respectively. The genomic soil DNA was extracted with further application of the Polymerase Chain Reaction associated to the Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technique. Ametryne application changed the structure of microbial community in both soils, but this change was more pronounced in the NVef soil, mainly in the initial periods of incubation. The sequencing data showed predominance of the following phyla: Proteobacteria, Acidobacteria, Actinobacteria, and Bacteroidetes. There was selection of certain phyla in the NVef, even only with 7 days of ametryne application; however, there was no reduction in the phyla number in the RQo. This led to the conclusion that microbial population diversity may vary with ametryne application, but it will depend on the soil type

ASSUNTO(S)

ametryne diversity biodegradabilidade ametrina dgge diversidade biodegradation. dgge

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