A research team has developed a synthetic microbial consortium that completely reduces soluble uranium [U(VI)] to insoluble U(IV) within 48 hours, showing nearly twice the efficiency of a single-strain system. The study reveals how Shewanella oneidensis MR-1 and Pseudomonas aeruginosa LXZ1 cooperate to accelerate extracellular electron transfer (EET).
P. aeruginosa LXZ1 secretes pyocyanin, which interacts with the outer-membrane cytochrome OmcA in MR-1, while its extracellular DNA forms conductive networks within the biofilm. These mechanisms jointly enhance electron flow and energy metabolism, overcoming the limitations of conventional microbial reduction. The findings highlight a community-based approach for sustainable uranium bioremediation.
READ MORE: Meet the microbes revolutionising the sustainable recovery of critical metals
READ MORE: Scientists translate nuclear waste site data into microbial ecosystem insights
Uranium contamination from mining and natural leaching threatens groundwater safety due to the high solubility and mobility of hexavalent uranium [U(VI)]. Bioreduction by dissimilatory metal-reducing bacteria converts soluble U(VI) to insoluble U(IV), offering an environmentally friendly remediation strategy. However, this process is often limited by low redox mediator production and poor biofilm conductivity in single-species systems. Synthetic microbial communities that combine complementary metabolic and electron-transfer functions may provide a more efficient alternative. Due to these limitations, it is necessary to investigate cooperative microbial systems that can achieve faster and more complete uranium reduction.
Synthetic microbial consortium
A study by the University of South China and Xi’an University of Technology, published (DOI: 10.1016/j.ese.2025.100629) in Environmental Science and Ecotechnology in October 2025, reports a synthetic microbial consortium capable of complete uranium reduction within 48 hours. The system combines Shewanella oneidensis MR-1, a model metal-reducing bacterium, with Pseudomonas aeruginosa LXZ1 isolated from uranium-contaminated soil. Through electrochemical experiments, molecular simulations, and gene expression analysis, the researchers revealed how phenazine-mediated electron transfer and extracellular DNA jointly improve the efficiency of microbial uranium reduction.
The researchers co-cultured S. oneidensis MR-1 with P. aeruginosa LXZ1, forming a synthetic microbial community that removed 75% of uranium within 12 hours and achieved complete reduction after 48 hours, compared with 60% by MR-1 alone. This improvement arose from two complementary mechanisms. P. aeruginosa LXZ1 secreted pyocyanin, a redox-active phenazine, which bound to MR-1’s outer-membrane cytochrome OmcA and shifted its redox potential, facilitating directional electron flow and reducing proton-transfer constraints.
Meanwhile, P. aeruginosa LXZ1 released extracellular DNA (eDNA) that organized into conductive structures, enhancing electron transport across the biofilm. Electrochemical gating tests showed a fourfold increase in current output, which decreased sharply after DNase I digestion, confirming the essential role of eDNA. Transcriptomic results indicated upregulation of metabolic and EET-related genes (ldh, ndh, fdh, pflB, ackA), along with higher NAD⁺/NADH ratios and ATP levels. Together, these processes established a stable and efficient electron-transfer network for uranium immobilization.
Metal reduction
“Our results show how naturally occurring microbial interactions can be used to improve metal reduction efficiency,” said Dr. Xizi Long, corresponding author of the study. “By combining Shewanella and Pseudomonas, we achieved a balance between metabolic complementarity and electron transfer enhancement. Pyocyanin functions as an intercellular redox mediator, while extracellular DNA provides a conductive matrix. This cooperative design illustrates how microbial communities can be organized for more effective environmental remediation.”
The synthetic microbial consortium offers a feasible and sustainable method for uranium-contaminated soil and groundwater treatment. Its design demonstrates how interspecies electron exchange can improve the stability and conductivity of biofilms, potentially extending to other redox-active pollutants such as chromium, arsenic, or technetium. Beyond environmental cleanup, the findings deepen understanding of microbial electrochemical cooperation and may inform future developments in bioenergy conversion and microbial material design. This approach exemplifies how ecological cooperation principles can be applied to optimize bioremediation efficiency in complex environments.
No comments yet