Biodegradation and Ecotoxicity of Poly(1-Hexene-Maleic Anhydride): Insights into Environmental Behavior and Biological Impact

The persistent accumulation of polymers in terrestrial ecosystems poses significant environmental challenges. Herein, the biodegradation of poly(1-hexene-maleic anhydride) (HMA) in soil and <i>Pseudomonas aeruginosa</i> was investigated to mitigate its environmental impact. The experimental results revealed that the mineralization rate of HMA reached 17.6% after 90 days of incubation in soil. Bacterial degradation led to a 79.0% weight loss after cultivation with <i>Pseudomonas aeruginosa</i> for 30 days. In addition, HMA exposure induced distinct shifts in soil microbial communities, with <i>Proteobacteria</i> abundance increasing from 40.3 to 48.9% after the initial 5 days but subsequently declining to 34.6% due to the inhibitory effects of biodegradation intermediates. Furthermore, phytotoxicity assays demonstrated that soybean seedlings exhibited pronounced root elongation, reduced lateral root formation, and elevated oxidative stress biomarkers after HMA exposure. Earthworm (<i>Eisenia fetida</i>) tests revealed that the biotoxicity of HMA depended on both concentration and exposure time. The median lethal concentration after 24 h was 3.63 mg/cm², and the mortality rate reached 46.7% after 14 days in soil. Progressive degradation of HMA mitigated both oxidative stress and biotoxic effects over time, indicating a self-attenuating ecological risk profile. These findings provide a comprehensive understanding of the environmental behavior, biodegradation mechanisms, and biotoxic effects of HMA, offering valuable insights for the design and assessment of sustainable petroleum-based polymers.