The study examines how interfacial stresses within droplets and flowing fluids influence bacterial survival and virulence in ways that have often been overlooked.
“Bacteria frequently experience fluid motion in their natural environments, from water bodies to human capillaries, but this phenomenon has been largely ignored by researchers. Our research shows that the stresses caused by fluid flows can trigger important changes in bacterial cells,” lead author Siddhant Jain said.
The paper discusses several key environments where bacteria experience fluid-induced stresses. In evaporating droplets, the interfacial forces and flow patterns can affect where bacteria end up and how they survive the drying process.
“Interestingly, bacteria that dry at the edges of droplets often show higher viability and virulence compared to those in the centre. Airborne droplets create a different stress environment, with bacteria in levitated droplets often showing higher viability but potentially becoming more virulent,” the researchers said.
When droplets containing bacteria impact surfaces at high speeds, such as during a sneeze, the forces involved can alter bacterial physiology, potentially pushing bacteria into a viable but non-culturable state and increasing their ability to infect host cells. In flowing fluids like blood vessels or industrial pipes, bacteria experience shear forces that can trigger genetic changes altering their behaviour and virulence.
“Understanding how bacteria respond to these fluid environments is crucial for addressing real-world problems… It has implications for disease transmission, especially during events like the Covid-19 pandemic, as well as for developing new strategies to combat antibiotic-resistant infections,” co-author Professor Saptarshi Basu said.
Researchers highlight several areas where further research is needed, including decoupling the effects of fluid stresses from other stresses bacteria experience, investigating how different surfaces and deposition methods affect bacterial survival on fomites, exploring the genetic mechanisms behind how bacteria sense and respond to fluid stresses, and using advanced technologies like organ-on-chip models to study bacterial behaviour in more realistic environments.
The study emphasises that most previous studies on bacterial physiology have used static culture conditions that don’t reflect the dynamic fluid environments bacteria encounter in nature. By incorporating fluid dynamics into microbiology research, scientists may gain new insights into how bacteria survive, spread, and cause disease.
As antibiotic resistance continues to pose a growing threat to global health, understanding these fundamental aspects of bacterial behaviour could lead to novel approaches for preventing and treating infections. Researchers hope their findings will inspire more interdisciplinary research combining microbiology, fluid mechanics, and bioengineering to tackle these important questions.
“This field is both complex and fascinating. By considering these dynamic flow conditions, we may uncover surprising new findings that could ultimately enhance human health,” another co-author, Dipshikha Chakravortty, said.