Composite Bacteria Breakthrough: Enhanced Biodegradation of Hydrolyzed Polyacrylamide for a Cleaner Oilfield Future

A New Microbial Alliance for Cleaner Oilfields

The global oil industry faces a persistent environmental challenge — wastewater contaminated with hydrolyzed polyacrylamide (HPAM), a polymer used in enhanced oil recovery. While HPAM improves crude extraction, its residues cause severe ecological and operational problems, from reservoir blockages to the release of toxic acrylamide monomers.

In an innovative study published in Biodegradation (2025) by researchers from the China University of Petroleum (East China), scientists identified and optimized a powerful composite bacterial system capable of efficiently degrading HPAM and breaking down stubborn polymer gels.

Meet the Microbial Duo: Agrobacterium pusense and Stutzerimonas balearica

From oilfield wastewater samples, ten HPAM-degrading bacterial strains were initially screened. Among them, Agrobacterium pusense (NMYGYA2) and Stutzerimonas balearica (SCE1) stood out for their synergy. When combined, these bacteria achieved a remarkable 81.2% HPAM removal efficiency — outperforming all previously reported single or mixed strains.

“The composite system not only degrades HPAM faster but also works effectively at temperatures up to 55°C,”.

This robustness makes the bacteria ideal candidates for field-scale bioremediation of polymer-contaminated wastewater and blocked oil reservoirs.

How It Works: The Science of Biodegradation

Through enzyme-driven reactions, the composite bacteria hydrolyze the amide groups in HPAM and cleave carbon-carbon bonds in the polymer chain. Analytical methods like Fourier Transform Infrared Spectroscopy (FTIR) and Gel Permeation Chromatography (GPC) revealed that HPAM’s molecular weight dropped dramatically — from 3.7 × 10⁶ Da to 1.9 × 10⁵ Da after degradation.

Crucially, no carcinogenic acrylamide monomer was detected after the process, confirming the method’s environmental safety.

Optimization and Results: A Biotech Milestone

The researchers optimized the culture conditions to boost biodegradation:

Urea (800 mg/L) as a nitrogen source
Glucose (500 mg/L) as a carbon source
CaCl₂ (50 mg/L) to enhance enzyme activity

Under these optimized conditions, the composite culture achieved 81.2% HPAM degradation — the highest rate recorded so far.

Condition	HPAM Removal Efficiency
Before optimization	45.9%
After optimization	81.2%

Gel-Breaking Power for Oilfield Applications

Beyond biodegradation, the bacterial pair showed impressive gel-breaking ability, reducing HPAM gel viscosity by over 60%. This breakthrough could help unblock oil wells, improving recovery rates while minimizing environmental damage.

“These bacteria could become bio-based alternatives to chemical gel breakers used in oilfields,”

Why It Matters: Toward Sustainable Oilfield Bioremediation

The environmental footprint of polymer flooding in oilfields is a growing concern. Traditional chemical degradation methods are costly and polluting. This microbial solution offers a low-cost, eco-friendly, and highly efficient alternative, aligning with global efforts toward greener energy and industrial practices.

For related research on sustainable microbial bioremediation, see Frontiers in Environmental Science.

Conclusion

The synergistic combination of Agrobacterium pusense and Stutzerimonas balearica represents a major advancement in HPAM biodegradation and gel-breaking technology. By optimizing microbial cooperation, this research paves the way for eco-innovations in wastewater treatment and oilfield management.

The next frontier? Exploring how quorum sensing — the bacterial communication system — influences such synergistic biodegradation processes.

Reference

Wang, J., Zhang, X., Han, H., Jia, Y., Zhang, H., Jia, Y., & Li, H. (2025). Improved hydrolyzed polyacrylamide biodegradation and gel breaking performance of composite bacteria. Biodegradation, 36(5), 101. https://doi.org/10.1007/s10532-025-10196-4