Electroactive properties of EABs in response to long-term exposure to polystyrene microplastics/nanoplastics and the underlying adaptive mechanisms.

Given widespread presence of polystyrene (PS) microplastics/nanoplastics (MPs/NPs), the electroactive responses and adaptation mechanisms of electroactive biofilms (EABs) exposed long-term to PS-containing aquatic environments remain unclear. Therefore, this study investigated the impacts of PS MPs/NPs on electroactivity of EABs. Results found that EABs exhibited delayed formation upon initially exposure but displayed an increased maximum current density (Imax) after subsequent exposure for up to 55 days. Notably, EABs exposure to NH2PS NPs (EAB-NH2PSNPs) demonstrated a 50% higher Imax than the control, along with a 17.84% increase in viability and a 58.10% increase in biomass. The cytochrome c (c-Cyts) content in EAB-NH2PSNPs rose by 178.35%, benefiting the extracellular electron transfer (EET) of EABs. Moreover, bacterial community assembly indicated the relative abundance of electroactive bacteria increased to 87.56% in EAB-NH2PSNPs. The adaptability mechanisms of EABs under prolonged exposure to PS MPs/NPs predominantly operate by adjusting viability, EET, and bacterial community assembly, which were further confirmed a positive correlation with Imax through structural equation model. These findings provide deeper insights into long-term effects and mechanisms of MPs/NPs on the electroactive properties of EABs and even functional microorganisms in aquatic ecosystems.

Mechanistic insights into the response of electroactive biofilms to Cd2+ shock: bacterial viability and electron transfer behavior at the cellular and community levels.

Electroactive biofilms (EABs) play a crucial role in environmental bioremediation due to their excellent extracellular electron transfer (EET) capabilities. However, Cd2+ can have toxic effects on the electrochemical performance of EABs, and the comprehensive inhibition mechanism of EABs in response to Cd2+ shock remains elusive. This study indicated that Cd2+ shock significantly reduced biomass and increased oxidative stress in EABs at the cellular level. The bacterial viability of EABs in phase III under 0.5 mM Cd2+ shock (EABCd2+-III0.5) decreased by 16.31% compared to EABCK-III. Moreover, intracellular NADH, c-Cyts, and the abundance of electroactive species were essential indicators to evaluate EET behavior of EABs. In EABCd2+-III0.5, these indicators decreased by 26.32%, 33.40%, and 20.65%, respectively. Structural equation modeling analysis established quantitative correlations between core components and electrochemical activity at cellular and community levels. The correlation analysis revealed that the growth and electron transfer functions of EABs were predictive indicators for their electrochemical performance, with standardized path coefficients of 0.407 and 0.358, respectively. These findings enhance our understanding of EABs' response to Cd2+ shock and provide insights for improving their performance in heavy metal wastewater.