Characterization of dynamic plastisphere and their underlying effects on the aging of biodegradable and traditional plastics in freshwater ecosystems

Recently, biodegradable plastics (BPs) are emerging as a sustainable alternative to traditional plastics. When released into an aquatic environment, the biodegradable performance of BPs is influenced by biochemical processes, especially the developed plastisphere. However, studies addressing the biodegrading capacity of BPs and traditional plastics within the plastisphere are still limited. Here, we investigated plastisphere community variations and their capacity to biodegrade polyethylene terephthalate (PET) and starch-based plastics (SBP) for four time periods (15, 30, 45, and 80 days) in three freshwaters. Unexpectedly, there is no significant difference in the microbial communities and network structure of the plastisphere between SBP and PET. Moreover, SBP tended to age rapidly at the early stage (0-15 days), while the aging degree of SBP and PET did not display an obvious difference at 80 days. Partial least squares path modeling suggested that plastic aging was mainly dominated by keystone taxa of network and aquatic environmental factors. These results suggest that the aging rate of commercial BPs may not be as fast as we imagine in freshwaters (SBP ≈ PET), and the environmental behaviors of BPs in the aquatic environment should be paid more attention to.