11:15 〜 11:30
[AHW18-08] Microbial life on plastics and its implications for elemental cycling in the aquatic environment
Growing attention has been addressed on microbial attachment and biofilm formation on plastic debris especially on microplastics (MPs; sizes: < 5 mm) in the aquatic environment. Since the presence of MPs allows increased heterotrophic activities in the environment, exploring the biofilm-forming microbial communities in Plastisphere (microbial life on plastics) is key to a better understanding of their impact on aquatic biogeochemical cycling. Hence, the current study is focused on bacterial and fungal community composition, diversity, and structure in MP-associated biofilms to emphasize the potential alteration of elemental cycling by the presence of MPs in the coastal aquatic environment.
In this study, we collected MP, surface water, bottom sediment, and coastal sand samples from two contrasting coastal areas (Shin and Shinano Rivers in Ibaraki and Niigata prefectures, respectively) of Japan on a seasonal basis. Surface morphology and attached microorganisms on MPs were visually inspected by scanning electron microscopy (SEM). A high-throughput sequencing using Illumina MiSeq was performed in the collected samples to investigate the microbial community composition and diversity among different samples. In addition, different morphotypes (fiber, films, foams, and fragments) of MPs were applied to the microbial analysis to identify the substrate influence on microbial colonies.
The significantly different abundance of operational taxonomic units (OTUs) as well as community separation patterns by non-metric multidimensional scaling (NMDS) were observed in the samples which demonstrates the distinctive microbial community structure on anthropogenic MPs compared to other samples. The dominant bacterial phyla were Proteobacteria, Actinobacteriota, Bacteroidota, and Firmicutes which reaching to 90% of the total bacterial community. In addition, Ascomycota, Basidiomycota, Chytridiomycota, and Monoblepharomycota were observed to be the dominant fungal phyla in the samples. Our results reveal that distinct microbial assemblages on MPs that different from those in the ambient environment. Furthermore, differences in microbial taxa among the seasonal variation as well as morphotypes of MPs were observed. The results reveal the different metabolic functional diversity of microorganisms on MPs. The current research highlights the microbial diversity on MPs which could be useful to undercover the plastic-associated nutrient cycling in the aquatic environment.
Keywords: microplastics, biofilm-forming microorganisms, bacterial and fungal diversity, community composition, coastal river, seasonal variations.
Acknowledgments:
The authors thank Ms. Mutsumi Shimizu, Ms. Misuzu Kaminaga, Ms. Kikuko Yoshigaki, and Ms. Shinako Okano of the Japan Atomic Energy Agency (JAEA) for support with the laboratory and field work; Dr. Eriko Suzuki and Dr. Afiqa Mohamad of JAEA for assistance with the SEM analysis. We also acknowledge the great support from Dr. Hiro Nagano from Niigata University, Dr. Shunsuke Matsuoka from Kyoto University, and Dr. Toshiaki Kondo from Japan International Research Center for Agricultural Sciences with microbial analysis. This work was supported by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Research Activity Start-up (grant number: 21K21336).
In this study, we collected MP, surface water, bottom sediment, and coastal sand samples from two contrasting coastal areas (Shin and Shinano Rivers in Ibaraki and Niigata prefectures, respectively) of Japan on a seasonal basis. Surface morphology and attached microorganisms on MPs were visually inspected by scanning electron microscopy (SEM). A high-throughput sequencing using Illumina MiSeq was performed in the collected samples to investigate the microbial community composition and diversity among different samples. In addition, different morphotypes (fiber, films, foams, and fragments) of MPs were applied to the microbial analysis to identify the substrate influence on microbial colonies.
The significantly different abundance of operational taxonomic units (OTUs) as well as community separation patterns by non-metric multidimensional scaling (NMDS) were observed in the samples which demonstrates the distinctive microbial community structure on anthropogenic MPs compared to other samples. The dominant bacterial phyla were Proteobacteria, Actinobacteriota, Bacteroidota, and Firmicutes which reaching to 90% of the total bacterial community. In addition, Ascomycota, Basidiomycota, Chytridiomycota, and Monoblepharomycota were observed to be the dominant fungal phyla in the samples. Our results reveal that distinct microbial assemblages on MPs that different from those in the ambient environment. Furthermore, differences in microbial taxa among the seasonal variation as well as morphotypes of MPs were observed. The results reveal the different metabolic functional diversity of microorganisms on MPs. The current research highlights the microbial diversity on MPs which could be useful to undercover the plastic-associated nutrient cycling in the aquatic environment.
Keywords: microplastics, biofilm-forming microorganisms, bacterial and fungal diversity, community composition, coastal river, seasonal variations.
Acknowledgments:
The authors thank Ms. Mutsumi Shimizu, Ms. Misuzu Kaminaga, Ms. Kikuko Yoshigaki, and Ms. Shinako Okano of the Japan Atomic Energy Agency (JAEA) for support with the laboratory and field work; Dr. Eriko Suzuki and Dr. Afiqa Mohamad of JAEA for assistance with the SEM analysis. We also acknowledge the great support from Dr. Hiro Nagano from Niigata University, Dr. Shunsuke Matsuoka from Kyoto University, and Dr. Toshiaki Kondo from Japan International Research Center for Agricultural Sciences with microbial analysis. This work was supported by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Research Activity Start-up (grant number: 21K21336).