Fiscal Year
FY 2025
April 2025 – March 2026

Principal Investigator
Batdulam Battulga
Postdoctoral Researcher, Advanced Institute for Marine Ecosystem Change (WPI-AIMEC)

Co-Investigators
Takeshi Obayashi
Professor, Graduate School of Information Sciences
Minoru Ikeda
Division of Coastal Field Science for Biological Production, Department of Biological Production Science, Graduate School of Agricultural Science

Research Keywords
Microplastics ; Plastisphere ; Biofilm community ; Environmental dynamics analysis

1. Research Overview

Microplastics (plastic particles smaller than 5 mm) have become a major environmental concern because they persist in aquatic ecosystems and may influence biodiversity and ecosystem functioning. In aquatic environments, microplastic surfaces are rapidly colonized by microorganisms, forming biofilms collectively known as the Plastisphere. These microbial communities influence the environmental fate of microplastics and may contribute to nutrient cycling, microbial interactions, and other ecosystem processes. However, the composition, assembly, and ecological functions of Plastisphere communities remain insufficiently understood.

This project investigated the microbial community structure and potential ecological functions of biofilms associated with environmental microplastics collected from aquatic environments in Miyagi and Aomori Prefectures, Japan, and the Tuul River Basin, Mongolia. An interdisciplinary approach integrating field surveys, molecular microbial analyses, and bioinformatics was employed to compare Plastisphere communities across contrasting aquatic environments. Water, sediment, and environmental microplastic samples were collected from the study sites, and DNA extracted from microplastic-associated biofilms was analyzed using 16S rRNA amplicon sequencing. Bioinformatics analyses were conducted to characterize community composition, diversity, co-occurrence patterns, and predicted ecological functions. Comparative analyses were further performed to examine relationships between microbial communities and local environmental conditions.

The study revealed that microbial communities associated with microplastics differed in composition from those in the surrounding environmental media (i.e., water and sediment). Further analyses suggested that these communities exhibit distinct ecological characteristics across sampling locations, indicating that local environmental conditions influence the assembly and potential functions of the Plastisphere. These findings provide new insights into the microbial community structure and potential ecological functions of microplastic-associated biofilms across different aquatic environments. This study establishes a comparative dataset of Plastisphere microbial communities from freshwater and coastal environments in Japan and Mongolia and provides a framework for integrating molecular microbial ecology with bioinformatics to investigate microplastic-associated microorganisms. The resulting datasets and analytical approaches provide a valuable foundation for future studies aimed at understanding microbial colonization of environmental microplastics and developing data-driven approaches for aquatic environmental monitoring.

2. Significance of the Research and Future Prospects

This study advances our understanding of the ecological significance of microbial communities inhabiting microplastic surfaces in aquatic environments. By integrating environmental monitoring, molecular microbial analysis, and bioinformatics, the project established an interdisciplinary framework for investigating the interactions between microplastics and microorganisms.

The findings demonstrate that the Plastisphere contains site-specific microbial communities with distinct ecological characteristics, highlighting its potential as an indicator of environmental conditions and ecosystem health. The analytical approaches developed in this project provide a valuable framework for future studies of aquatic microbial ecology and environmental monitoring.

In addition to microbial community data, this study generated comprehensive field observations on the physical characteristics and distribution of microplastics across different aquatic environments. These datasets provide an important foundation for developing next-generation monitoring approaches. In future research, we aim to integrate field observations with artificial intelligence (AI)-based image analysis to improve the detection and characterization of microplastics. Such approaches have the potential to reduce the time, labor, and cost associated with conventional field surveys while enabling more efficient, scalable, and continuous environmental monitoring through AI-assisted predictive models.

The results will support future research on the ecological consequences of microplastic pollution, contribute to collaborations on aquatic ecosystem conservation, and provide a scientific basis for developing innovative monitoring strategies and environmental management policies.

3. Conclusion

Microplastics provide surfaces for microorganisms to form biofilms known as the Plastisphere, creating unique microbial habitats in aquatic environments. This project investigated the microbial communities associated with microplastics collected from aquatic environments in Japan and Mongolia using DNA sequencing and bioinformatics analyses. The study found that microbial community composition differed among sampling locations, suggesting that local environmental conditions shape the structure and potential ecological functions of the Plastisphere. By combining environmental observations with metabarcoding and bioinformatics analyses, this research establishes a framework for characterizing microplastic-associated microbial communities and provides a scientific basis for future environmental monitoring.