Integrated metagenomic model insight towards understanding the effects of biochar on microplastics degradation in flooded soil

Soil microbial communities, containing a rich tapestry of bacteria, fungi, and archaea, serve as the cornerstone of terrestrial ecosystems, orchestrating essential biogeochemical processes and maintaining ecological balance. However, the emergence of microplastics pollution has cast a shadow over these vital ecosystems. Microplastics, minute plastic particles measuring less than 5mm, have infiltrated soils globally, ushering in a new era of environmental challenges. Beyond their physical presence, microplastics introduce novel contaminants into these ecosystems, potentially reshaping the composition and functionality of soil microbial communities. Currently, the detection and the removal of microplastics in terrestrial ecosystems have emerged as areas of significant research focus and challenge. Metagenomics is a transformative branch of genomics that allows the direct study of genetic information obtained from environmental samples. It allows for a closer examination of the functionality of complex soil microorganisms and their responses to environmental stressors. To unravel the complex relationship of interactions between microplastic pollution and soil microbial communities, the research reported in this PhD thesis employed an integrated metagenomic strategy, which offers an all-encompassing view of the genetic diversity and metabolic potential of these intricate ecosystems. The studies associated to the present project investigate the capacity of microorganisms and functional materials such as biochar and magnetic biochar to perform soil remediation. The final results showed that members of the genus Nocardia and Pseudomonas present in the soil are able to degrade microplastics and plasticizers together with magnetic biochar. Additionally, it was observed that polyvinyl chloride microplastics exhibited higher methane emission potential than other thermoplastic microplastics. Furthermore, we extended the application of this integrated genomic approach to a sludge system, also characterized by anaerobic conditions, and elucidated the response of microorganisms within the sludge to nanoparticles. These studies thus shed light on the microbial communities structure and their responses to emerging pollutants. The findings from these investigations hold the promise of informing targeted strategies for the remediation of microplastic-contaminated soils and the sustainable management of waste-activated sludge. In the face of burgeoning environmental challenges, this research endeavors to provide a novel perspective for mitigating the ecological repercussions of emerging pollutants in terrestrial ecosystems, thus safeguarding the delicate balance of our planet's soils and their microbial inhabitants.