Bacterial centimeter-long electron transfer enhances attenuation of polycyclic aromatic hydrocarbons in freshwater sediment: A mechanistic mini-review

Natural cable bacteria and engineered bio-electrochemical snorkels enable centimeter-scale long-distance electron transfer (LDET) and have been shown to markedly enhance attenuation of polycyclic aromatic hydrocarbons (PAHs) in freshwater sediment. While the mechanisms of cable bacteria are well understood, those by which snorkel enhances attenuation of PAHs remain poorly defined. Because dissolved organic matter (DOM) binds the majority of PAHs in freshwater sediment, the transformation and eventual attenuation of PAHs is theoretically governed by DOM dynamics. Our previous studies preliminarily indicate that the snorkel alters DOM in its photo-chemical and electro-chemical characteristics. Inspired by those findings, this manuscript further reviews current knowledge on how DOM influences transformation of PAHs, summarizes the key DOM attributes involved in transformation of PAHs, analyzes how snorkel modulates these critical DOM attributes, and finally outlines four pathways by which snorkel enhances attenuation of PAHs. Although substantial work is required to validate these proposed pathways and to quantify their respective contributions, this mini-review significantly extends current limited studies including our own and provides the first in-depth analysis of how bacterial LDET enhances attenuation of PAHs, which can guide future sediment remediation strategies that leverage snorkel or other emerging electroactive bacteria-based technologies.

Graphical abstract

The alternative text for this image may have been generated using AI.