O impacto de microplásticos associados ao glifosato e à variação térmica nas comunidades microbianas do solo e da plastisfera

Abstract

The rise of microplastics and pesticide residues in soils represents emerging concerns regarding the health of edaphic environments. This study aimed to evaluate the impact of microplastics on the ecosystem, investigating the effects of polystyrene and polyurethane particles, with and without the presence of the herbicide glyphosate, in Latosol soil, under controlled thermal conditions of 25 °C and 35 °C. The experimental design included 45 samples divided into three groups with nine treatments. The first group was at 25 °C, containing the treatments: control soil, soil with added polystyrene, and soil with polyurethane. The second group maintained the same pattern but the temperature was 35 °C. The third group consisted of soil treatments with glyphosate, soil plus polystyrene and glyphosate, and finally, soil with polyurethane and glyphosate. The units were isolated and placed in a biochemical oxygen demand (BOD) incubator. After a 45-day incubation period, the samples were sequenced, highlighting and amplifying the V4-V5 region of the 16S rRNA gene, via the Illumina MiSeq platform. The sequences were processed using the QIIME 2 pipeline with the q2-DADA2 plugin. The results revealed significant changes in the diversity and composition of phyla in response to the different treatments, demonstrating the plastisphere as a restrictor of ecological niches (p = 3.75×10⁻⁸), especially under thermal stress conditions at 35 °C. The temperature of 25 °C integrated with polystyrene showed greater diversity of phyla, presenting greater colonization for the Bacteroidota phylum, while associated with polyurethane, groups such as Chloroflexi and Firmicutes were evident. Glyphosate, in turn, acted selectively, reducing sensitive phyla such as Acidobacteriota and Planctomycetota, while the dominance of Actinobacteriota and Firmicutes prevailed. These findings corroborate that the interaction between microplastics, herbicides, and thermal variation act as modulating agents of the soil microbiota, propagating synergistic effects of emerging contaminants and climate change on soil functionality.