Microplastics (MPs) are emerging pollutants whose occurrence is a global problem in natural ecosystems including soil. Among MPs, polyvinyl chloride (PVC) is a well-known polymer with remarkable resistance to degradation, and because its recalcitrant nature serious environmental concerns are created during manufacturing and waste disposal. The effect of PVC (0.021% w/w) on chemical and microbial parameters of an agricultural soil was tested by a microcosm experiment at different incubation times (from 3 to 360 days). Among chemical parameters, soil CO₂ emission, fluorescein diacetate (FDA) activity, total organic C (TOC), total N, water extractable organic C (WEOC), water extractable N (WEN) and SUVA₂₅₄ were considered, while the structure of soil microbial communities was studied at different taxonomic levels (phylum and genus) by sequencing bacterial 16S and fungal ITS2 rDNA (Illumina MiSeq). Although some fluctuations were found, chemical and microbiological parameters exhibited some significant trends. Significant (p < 0.05) variations of soil CO₂ emission, FDA hydrolysis, TOC, WEOC and WEN were found in PVC-treated soils over different incubation times. Considering the structure of soil microbial communities, the presence of PVC significantly (p < 0.05) affected the abundances of specific bacterial and fungal taxa: Candidatus_Saccharibacteria, Proteobacteria, Actinobacteria, Acidobacteria and Bacteroides among bacteria, and Basidiomycota, Mortierellomycota and Ascomycota among fungi. After one year of experiment, a reduction of the number and the dimensions of PVC was detected supposing a possible role of microorganisms on PVC degradation. The abundance of both bacterial and fungal taxa at phylum and genus level was also affected by PVC, suggesting that the impact of this polymer could be taxa-dependent.

Biodegradable mulching films offer an eco-friendly alternative to petroleum-based plastics in agriculture, but their effects on soil parameters are not well understood. A microcosm experiment (20 °C, 75% field capacity) investigated the impact of two doses (0.021% and 1% w/w) of a biodegradable polymer on soil chemical and microbiological properties over a year. The 1% dose significantly (p < 0.05) increased CO₂ emissions, water-extractable organic C, and hydrolytic activity. A significant (p < 0.05) effect on microbial alpha- and beta-diversity was noted only during short- and medium-term incubations. In contrast, a taxon-related response was found for both bacterial and fungal taxa affecting the abundance of the genera Aquicella, Cellvibrio, Bacillus, Ramlibacter, and Saccharibacteria genera incertae sedis among bacteria, and Malassezia, Orbilia, and Rhodotorula among fungi (including both yeast and filamentous lifestyles). Microbial functions revealed a greater impact on fungal communities compared to bacterial ones. However, after one year of exposition, only a marginal effect on the abundance of both bacterial and fungal functional groups was found in the microcosms. A significantly higher concentration of tightly bound exopolysaccharides in the presence of 1% biodegradable polymer at the start of the experiment suggested their key role in microbial degradation of bioplastics via biofilm formation.

To investigate the combined impacts of temperature and plant residues on the mineralization capacity of soil organic matter, in addition to the impact on the taxonomic composition and activity of the soil microbiome, a 364-day experiment involving gray forest soil (Greyzemic Phaeozem Albic) was conducted under controlled laboratory conditions. Three substrate treatments were applied, control (C), amendment with aspen leaves (L), and amendment with aspen branches (B), combined with three temperature regimes (2, 12, and 22 °C). The results showed that long-term experimental warming reduced microbial alpha diversity (number of species and richness), increased microbial respiration and decomposition rates, and altered community composition. Over the year, the percentage of mineralization of added carbon was higher for leaves (29.9%–57.8%) than for branches (20.1%–47.6%). The efficiency of organic matter decomposition increased by 1.5- to 2-fold between 2 and 12 °C. Across all treatments, Proteobacteria were found to be the dominant phylum. According to α-diversity analysis, leaves served as the most preferred substrate for enhancing species representation. β-diversity analysis results indicated that temperature was the most significant factor shaping the microbial community’s structure. Our research findings provide new insights into soil organic matter formation and highlight the need for further research on microbial functional genes.

Microplastics are emerging pollutant found in many ecosystems including soil. Within them, polyvinyl chloride (PVC) is one of the most toxic polymers and is known for its remarkable resistance to degradation. The recalcitrant nature of PVC and the improper waste disposal could cause serious environmental concerns. In addition, the possible fragmentation and accumulation of small plastic particles in agricultural soils might have impacts on soil chemical and microbiological properties. Based on these considerations, a microcosm experiment was set up to investigate the effects of PVC microplastics (0.021% w/w) on soil chemical properties and soil bacterial and fungal communities at different incubation times (from 3 to 360 days).Among chemical parameters, soil CO2 emissions, fluorescein diacetate hydrolysis (FDA), total organic C (TOC), total N, water extractable organic C (WEOC), water extractable N (WEN) and SUVA254 were investigated, while the structure of soil microbial communities was studied at different taxonomic levels (phylum and genus) by sequencing bacterial 16S and fungal ITS2 rDNA (Illumina MiSeq). The number and the dimensions of PVC particles were also evaluated after one year of experiment.The results showed that the presence of PVC particles in soil caused significant (p < 0.05) variations in chemical parameters in short- and medium-term, thus suggesting that the presence of this polymer in soil can affect the turnover of organic matter. In the long period, instead, an increase of the soil enzymatic activity (FDA) was observed.The analysis of microbiological parameters showed that PVC microplastics significantly affected (p < 0.05) the structure of soil microbial communities changing the abundances of specific bacterial and fungal taxa: Acidobacteria, Actinobacteria, Bacteroides, Candidatus_Saccharibacteria, and Proteobacteria, , among bacteria, and Ascomycota, Basidiomycota, and Mortierellomycota among fungi, suggesting that the impact of this polymer could be taxa-dependent.A significant (p < 0.05) decrease of the number and dimensions of PVC particles was also detected after one year of incubation, supposing a possible role of microbial community on polymer degradation.

To investigate the combined impacts of temperature and plant residues on the mineralization capacity of soil organic matter and taxonomic composition and activity of the soil microbiome, a 364-day experiment with gray forest soil was carried out in a controlled laboratory conditions. Three substrate management, control (C), augmented with aspen leaves (L) and branches (B), and three temperature settings (2, 12, and 22^oC) comprised the treatment levels. According to the findings, long-term experimental warming reduced alpha diversity (number of species), increased microbial respiration and decomposition rates, and changed community composition. It has also lowered active soil organic matter. In comparison to branches, the percentage of mineralization in leaves was higher during the course of the year (29.9-57.8% and 20.1-47.6%, respectively). The efficiency of organic matter decomposition rose by 1.5 to 2 times between 2 and 12°C. It has been discovered that all experimental versions are dominated by Proteobacteria. According to α-diversity analysis, leaves were the most preferred substrate for increasing species representation. Temperature was the most significant factor affecting the microbial community’s structure, according to β-diversity data. Our research provides new insights into the soil organic matter formation, and raises interesting questions regarding the microbiological drivers of this process.