Recording and Analysis of the Impact of Microplastics on Soil Microbial Communities through Case Studies

Microplastics are synthetic solid particles of primary or secondary origin, mainly derived from the fragmentation and degradation of larger plastic materials.Pollution by plastics and microplastics is widespread in the environment, with aquatic ecosystems having been studied more extensively.In recent years, however, increasing research interest has been directed toward the contamination of terrestrial ecosystems by microplastics, which occur in various forms and originate from multiple sources and pathways of entry into soils.Numerous studies have been conducted to investigate the effects of microplastics on the physicochemical properties of soils, plant growth and soil microorganisms, and consequently on animal and human health, as microplastics have been shown to enter the food chain.The present thesis focuses on the identification and analysis of the effects of microplastics on soil microbial communities.To this end, data from scientific articles and case studies were collected, analyzed and comparatively evaluated.Soil microbial communities play a crucial role in biogeochemical cycles, soil fertility and plant growth.The reviewed studies indicate that microplastics, depending on polymer type, size, shape and concentration, affect the abundance, structure and composition of microbial communities, as well as gene expression, enzymatic activity, and microbial functional traits.Low concentrations of microplastics, mainly conventional polymers, were associated with transient increases in microbial activity and diversity, whereas higher concentrations and biodegradable polymers were linked to decreased alpha diversity, shifts in the relative abundance of key bacterial groups, and restructuring of functional processes related to microbial respiration and the biogeochemical cycles of carbon, nitrogen and phosphorus.These changes may lead to modifications in fundamental soil properties, such as pH, aggregate stability, and nutrient cycling, thereby indirectly affecting overall soil ecosystem functioning.Additionally, certain microorganisms have been reported to utilize microplastics as a carbon source.Finally, this thesis highlights the need for future research to address existing knowledge gaps, by considering different soil types, more realistic experimental approaches, longer time scales, and the combined presence of microplastics with other soil contaminants.