A new approach to extracting biofilm from environmental plastics using ultrasound-assisted syringe treatment for isotopic analyses

• Published in: The Science of the total environment 2022-11, Vol.849, p.157758-157758, Article 157758
• Main Authors: Battulga, Batdulam, Atarashi-Andoh, Mariko, Nakanishi, Takahiro, Koarashi, Jun
• Format: Article
• Language: English
• Subjects: Biofilm; Coastal river; Plastic debris; Radiocesium (137Cs); Stable carbon (13C) and nitrogen (15N) isotopes
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.157758

Plastics are one of the ubiquitous and artificial types of substrates for microbial colonization and biofilm development in the aquatic environment. Characterizing plastic-associated biofilms is key to the better understanding of organic material and mineral cycling in the “Plastisphere”—the thin layer of microbial life on plastics. In this study, we propose a new method to extract biofilms from environmental plastics, in order to evaluate the properties of biofilm-derived organic matter through stable carbon (δ13C) and nitrogen (δ15N) isotope signatures and their interactions with radionuclides especially radiocesium (137Cs). The extraction method is simple and cost-effective, requiring only an ultrasonic bath, disposable plastic syringes, and a freeze drier. After ultrasound-assisted separation from the plastics, biofilm samples were successfully collected via a sequence of syringe treatments, with less contamination from plastics and other mineral particles. Effective removal of small microplastics from the experimental suspension was satisfactorily achieved using the method with syringe treatments. Biofilm-derived organic matter samples (14.5–65.4 mg) from four river mouths in Japan showed 137Cs activity concentrations of