ORIGINAL ABSTRACT

Glyphosate, the active ingredient in many broad-spectrum herbicides, is extensively used in agriculture but has come under increasing scrutiny due to its potential impacts on non-target microbial communities. To investigate these effects within a controlled yet ecologically relevant framework, Winogradsky columns, self-contained sediment-based ecosystems, were employed as a model system. A novel, non-destructive sampling approach was introduced using macroporous elastomeric silicone foam (MESIF) integrated in stainless-steel frames to enable spatiotemporal monitoring of benthic microbial communities. These MESIF-loaded frames were vertically embedded in columns filled with lake sediment and subjected to varying experimental conditions, including light exposure and glyphosate treatment. Microbial colonization of the MESIF was assessed via amplicon sequencing at defined time points. Glyphosate-treated columns exhibited delayed microbial stratification and diminished development of characteristic pigmentation associated with functional groups such as iron-oxidizing and sulfate-reducing bacteria. Although within-column alpha diversity remained relatively constant, glyphosate exposure led to distinct shifts in community composition, including an increased abundance of taxa potentially involved in glyphosate degradation. These findings demonstrate the effectiveness of combining Winogradsky columns with MESIF-based sampling for studying environmental stressors and underscore glyphosate's influence on microbial succession and functional diversity in sediment ecosystems.