Work

Potential role of anaerobic plant-associated bacteria in naphthenic acid degradation

Year: 2026

Type: article

Abstract: ABSTRACT Plant-associated microorganisms can break down many contaminants, including naphthenic acid fraction compounds (NAFCs)—one of the toxic contaminants in oil sands process-affected water (OSPW). One way to take advantage of these processes is to use constructed wetland treatment systems (CWTSs), where aquatic plants work in coordination with microorganisms to remediate OSPW. However, the dynamics of the microbial communities and the potential contribution of distinct bacteria and fungi inhabiting sediments, rhizosphere, and water that comprise these systems remain poorly understood. To address this, we planted water sedge ( Carex aquatilis ) in mesocosm-scale wetland systems and compared it with unplanted controls. Naphthenic acid fraction compound (NAFC) concentrations and microbial community dynamics among various mesocosm compartments were monitored using mass spectrometry and high-throughput sequencing of the bacterial-archaeal 16S rRNA gene and the fungal ITS2 region. Carex -planted mesocosms reduced NAFC concentrations more rapidly than the unplanted controls, which coincided with shifts in abundance for both bacterial and fungal communities, especially in the Carex rhizosphere. The strongest relationships between microbial taxa and the decrease in NAFC concentrations were for anaerobic bacteria, suggesting a prominent role for these bacteria in NAFC degradation in CWTS. This study highlights potential microbial targets for improving CWTS efficiency for NAFC detoxification during OSPW remediation. IMPORTANCE Naphthenic acid fraction compounds (NAFCs) represent one of the most toxic and persistent contaminants in oil sands process-affected water (OSPW), posing a significant environmental challenge. As oil sands operations continue, large volumes of OSPW have accumulated, requiring effective treatment before any potential environmental discharge. Our study explores bioremediation through constructed wetland systems as a sustainable approach to reduce NAFC concentrations. By uncovering the microbial dynamics involved in NAFC degradation, our research provides critical insights into the identification of microbial communities that can enhance the remediation process. This manuscript contributes to advancing the scientific foundation needed to develop effective, biological solutions for OSPW treatment.

Source: Applied and Environmental Microbiology

DOI: 10.1128/aem.00410-26