A photocatalytic Anammox@LC-COF biohybrid overcomes oxidative stress defense for resilient nitrogen removal.

Authors

Jiangshan Xi, Tingjun Dong, Guangchao Si, Li Zhang

Published in

Bioresource technology. Pages 136058. Oct 12, 2026. Epub Oct 12, 2026.

Abstract

Anaerobic ammonium oxidation (anammox) is central to low-carbon nitrogen removal, but its engineering application remains vulnerable to environmentally induced oxidative stress, whereby excessive reactive oxygen species (ROS) accumulation damages functional proteins and disrupts proteostasis. Here, we developed a low-crystallinity covalent organic framework-coupled anammox photocatalytic biohybrid, Anammox@LC-COF, to enhance oxidative stress defense and proteostasis through renewable photogenerated electron input. Results showed that Anammox@LC-COF exhibited broad tolerance to various engineering disturbances, including dissolved oxygen, low temperatures, pH fluctuations, and nitrite shocks. During 95 days of prolonged oxidative stress, Anammox@LC-COF sustained a robust total nitrogen removal efficiency of approximately 85%, whereas conventional anammox declined to 50.10%. It also increased the live-cell fraction, electron transport system activity, and specific anammox activity by 1.93-fold, 4.52-fold, and 3.28-fold, respectively. Mechanistic analysis indicated that LC-COF-derived photogenerated electrons established a coordinated antioxidative mechanism coupling front-end ROS interception with back-end proteostasis restoration. Specifically, photogenerated electrons activated a latent superoxide reductase-bacterioferritin-mediated ROS-scavenging pathway in anammox bacteria. Together with the traditional SOD-CAT antioxidant system, this dual pathway resulted in a 73.14% lower intracellular ROS level and curtailed oxidative damage at its source. In addition, photogenerated electrons enhanced the ferredoxin/thioredoxin reductive network by 1.97-fold, promoting chaperone-assisted refolding and quality control-mediated damaged protein clearance. This supported the recovery of core anammox metabolism under oxidative stress, with predicted HDH- and HZS-encoding gene abundances increasing by 4.26- and 1.43-fold, respectively. Overall, this photocatalytic biohybrid provides a broadly applicable solution to anammox environmental sensitivity, advancing its deployment in sustainable wastewater treatment.

PMID:
42863710
Bibliographic data and abstract were imported from PubMed on 13 Oct 2026.

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