Characterization and degradation mechanism of a newly isolated hydrolyzed polyacrylamide-degrading bacterium Alcaligenes faecalis EPDB-5 from the oilfield sludge

• Published in: Environmental pollution (1987) Vol. 363; no. Pt 1; p. 125124
• Main Authors: Yu, Yaqiu, Li, Yanshuo, Sun, Bingjian, Cui, Jinbo, Liu, Hao, Sun, Yuxiang, Xu, Qinglin, Boisse, Nicolas, Voelker, Francois, Matioszek, Dimitri, Favero, Cédrick, Kieffer, Johann, Li, Yiming, Lu, Jinren, Li, Haoshuai, Bao, Mutai
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-12-2024
• Subjects: Alcaligenes; Biodegradation; Genomics; Hydrolyzed polyacrylamide (HPAM); Polymer-flooding produced water; Biodegradation; Polymer-flooding produced water; Hydrolyzed polyacrylamide (HPAM); Alcaligenes; Genomics
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2024.125124

Hydrolyzed polyacrylamide (HPAM) is posing serious threats to ecosystems. However, biodegradation is an effective method to remove HPAM owing to its low cost and environmental friendliness. In this study, Alcaligenes faecalis EPDB-5 was isolated as a highly efficient HPAM degrading strain from sludge contaminated with polymerized produced water from Daqing oilfield. Under the optimal conditions, the strain EPDB-5 demonstrated an impressive HPAM degradation rate of 86.05%, the total nitrogen (TN) removal of 71.96% and chemical oxygen demand (COD) removal of 67.98%. Meanwhile, it can maintain a stable degradation rate higher than 75% under different pH and temperature conditions. 27 genes that play a key role in HPAM degradation were annotated by metagenomics sequencing. The key genes were involved in multiple KEGG pathways, including biofilm formation, biosynthesis secondary metabolites, and metabolic pathways. SEM, GPC, and FTIR analyses revealed that the structure of HPAM after biodegradation showed pores, a significant decrease in molecular weight, -NH2 detachment, and carbon chain breakage. Particularly, we propose a possible mechanism of biofilm formation - HPAM degradation - biofilm disappearance and reorganization. Moreover, the degradation rate of strain EPDB-5 on real wastewater containing HPAM was 29.97% in only three days. This work expands our knowledge boundary about the HPAM degradation mechanism at the functional gene level, and supports the potential of strain EPDB-5 as a novel auxiliary microbial resource for the practical application of HPAM.
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•Alcaligenes faecalis EPDB-5 isolated from HPAM-contaminated Daqing oilfield sludge.•Strain EPDB-5 showed 86.05% efficient degradation rate of HPAM.•Strain EPDB-5 exhibited excellent environmental adaptability.•Link genomic and epigenetic means to establish possible HPAM degradation mechanism.