Sun Yanchen

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Last Name
Sun
First Name
Yanchen
ORCID
0000-0003-1265-2738

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  • Article
    Distinct microbial communities degrade cellulose diacetate bioplastics in the coastal ocean
    (American Society for Microbiology, 2023-12-06) Sun, Yanchen ; Mazzotta, Michael G. ; Miller, Carolyn A. ; Apprill, Amy ; Izallalen, Mounir ; Mazumder, Sharmistha ; Perri, Steven T. ; Edwards, Brian ; Reddy, Christopher M. ; Ward, Collin P.
    Cellulose diacetate (CDA) is a bio-based plastic widely used in consumer products. CDA is a promising alternative to conventional thermoplastics due to its susceptibility to biodegradation in various environments. Despite widespread evidence for the degradation of CDA, relatively little is known about the microorganisms that drive degradation, particularly in the ocean. Recently, we documented the biodegradation of CDA-based materials (i.e., fabric, film, and foam) in a continuous-flow natural seawater mesocosm on the timescales of months, as indicated by mass loss, enzyme activity, and respiration to carbon dioxide. These findings paved the way for the present study aimed at identifying key microbial taxa implicated in CDA degradation. Analysis based on 16S rRNA gene amplicon sequencing of bacteria and archaea revealed that material type, incubation time, material morphology (e.g., fabric vs film), and plasticizer content significantly influenced the microbial community structure. Differential abundance analysis revealed that bacterial taxa affiliated with the families of Arenicellaceae, Cellvibrionaceae, Methyloligellaceae, Micavibrionaceae, Puniceicoccaceae, Spirosomaceae, and Thermoanaerobaculaceae, and the order of Pseudomonadales potentially initiated the degradation (i.e., deacetylation) of CDA fabric and film. These taxa were notably distinct from CDA-degrading microbes reported in non-seawater environments. Collectively, the findings lend further support for CDA as a promising next-generation, high-utility, and low-environmental persistence bioplastic material.
  • Article
    Strategies to reduce the environmental lifetimes of drinking straws in the coastal ocean
    (American Chemical Society, 2024-01-30) James, Bryan D. ; Sun, Yanchen ; Izallalen, Mounir ; Mazumder, Sharmistha ; Perri, Steven T. ; Edwards, Brian ; de Wit, Jos ; Reddy, Christopher M. ; Ward, Collin P.
    Nonpersistence in natural environments with benign degradation products is a growing design criterion for consumer plastics. However, data on their biodegradation rates and environmental lifetimes in the coastal ocean are lacking, limiting informed engineering and regulatory decisions. Single-use drinking straws, a common marine litter relevant to key stakeholders, exemplify this. To fill this knowledge gap, commercial drinking straws made of cellulose diacetate (CDA), polyhydroxyalkanoates (PHA), paper, polylactic acid (PLA), and polypropylene (PP) were incubated for 16 weeks in a flow-through seawater mesocosm and monitored for degradation and microbial community composition. CDA, PHA, and paper straws reduced in mass by up to 50%, projecting environmental lifetimes of 10–20 months in the coastal ocean. PP and PLA showed no measurable mass loss. Lifetimes depended on the material and dimensions of the straw, demonstrating the need to balance function and degradation properties. The materials that biodegraded exhibited unique microbial communities driven by chemical structure, whereas those materials that were persistent exhibited similar communities despite substantial differences in chemical structure. To reduce the persistence of drinking straws, we hypothesized that changing the product form (i.e., surface area), not just the material, can reduce their environmental lifetimes. To test our hypothesis, we evaluated the biodegradation of a prototype foamed CDA straw. Its specific surface degradation rate was more than double that of its solid counterpart, resulting in a shorter projected environmental lifetime than the paper straws. Our findings provide the initial constraints of the environmental lifetimes of several commercial drinking straws and identify strategies to design next-generation bioplastic consumer products with reduced persistence.