By Abbas Nazil
Scientists at Tohoku University have developed a new bacterial energy model that explains how antimicrobial resistance spreads in aquatic environments.
The study reveals that bacteria strategically redistribute their limited energy resources when exposed to environmental stressors such as heavy metals.
This process directly influences their ability to grow, form protective biofilms, tolerate pollutants, and transfer resistance genes to nearby bacteria.
The findings provide important insights into how pollution can unintentionally accelerate the global antimicrobial resistance crisis.
The research was led by Assistant Professor Katayoun Amirfard and Professor Daisuke Sano from Tohoku University in Japan.
Their work was published in the peer-reviewed journal *Water Research* on December 18, 2025.
Antimicrobial resistance occurs when bacteria evolve mechanisms that allow them to survive substances designed to kill them.
While these defenses improve survival, they require significant energy investment.
Because bacteria have limited energy, they must constantly balance competing biological needs.
The researchers sought to understand how this balance shifts in water environments under chemical stress.
The team focused on zinc oxide, a widely used industrial material frequently detected in aquatic systems.
Zinc oxide is commonly released into water through manufacturing, personal care products, and urban runoff.
Using laboratory data, scientists examined bacterial growth rates, biofilm mass, population density, and gene-transfer efficiency.
These values were incorporated into a mathematical framework based on Dynamic Energy Budget theory.
The model tracked how bacterial energy allocation changed over time following zinc oxide exposure.
Results showed that early exposure caused bacteria to divert energy toward metal resistance mechanisms.
This shift reduced the energy available for conjugation, the process through which resistance genes spread between bacteria.
At higher zinc oxide concentrations, biofilm formation was also significantly weakened.
However, under moderate stress, bacteria were still able to maintain enough energy to pass resistance traits to neighboring cells.
This finding highlights a critical tipping point where environmental pollution may promote antimicrobial resistance rather than suppress it.
According to the researchers, understanding these thresholds is essential for effective water management.
Professor Sano noted that the model offers valuable clues for preventing resistant bacteria from spreading in natural water systems.
Assistant Professor Amirfard emphasized that environmental pathways of antimicrobial resistance remain poorly understood globally.
She stated that most existing research focuses on hospitals and clinical settings rather than rivers, lakes, and wastewater.
The study provides the first mechanistic explanation of how bacteria prioritize energy under environmental pressure.
This approach allows scientists to predict how pollutants influence resistance dynamics over time.
Experts say the findings could support improved pollution control policies and wastewater treatment strategies.
The research also offers a scientific foundation for assessing long-term public health risks linked to contaminated water.
As antimicrobial resistance continues to rise worldwide, environmental insights such as these are becoming increasingly critical.
The authors hope the model will guide future research and inform sustainable approaches to water quality protection.
