PHA Microplastic Aging Decreases N2O Sink Capacity: Released γ-Butyrolactone Decouples Denitrifying Electron Transfer and Oxidative Phosphorylation

• DOI: 10.1021/acs.est.4c07717
• Publication Date: 2025-01-09T07:45:40Z
• Authors: Yu Zhang; Jing Lu; Xiao-Zheng Zhang; Zheng-Zhe Zhang; Ren-Cun Jin
• Keywords: Sink (geography)

Bacterial denitrification is a main pathway for soil N2O sinks, which crucial assessing and controlling emissions. Biobased polyhydroxyalkanoate (PHA) microplastic particles (MPs) degrade slowly in conventional environments, remaining inert extended periods. However, the impacts of PHA aging on bacterial sink capacity before degradation remain poorly understood. Here, model strain Paracoccus denitrificans was exposed to 0.05-0.5% (w/w) virgin aged MPs. Although no significant changes molecular weights were observed, MPs hindered cell growth reduction rates, leading surge 1H NMR spectroscopy UPLC-QTOF-MS analysis identified γ-butyrolactone as key component released from Metabolic verifications at cellular level confirmed its inhibition ATP synthesis. The that protonated hydrolyzed spontaneously periplasm would compete protons with ATPase destroy coupling between denitrifying electron transfer oxidative phosphorylation. Consequently, energy-deficient cells reduced supply reduction, did not contribute energy conservation. This work unveils novel mechanism by impairs highlights need consider environmental risks posed biobased aging.