BRITISH scientists have shed new light on exactly how disinfectants destroy harmful bacteria, in research that could help develop more effective products in the fight against infection and antimicrobial resistance.
Researchers led by The University of Manchester, working with British industry and scientists at the Science and Technology Facilities Council’s ISIS Neutron and Muon Source, have investigated the microscopic processes that take place when common disinfectant ingredients encounter bacterial membranes.
The study found that two different disinfectant compounds can work more effectively when used together, with one helping the other penetrate and damage bacterial membranes.
The research, carried out in collaboration with industrial partner Arxada, was supported through a Biotechnology and Biological Sciences Research Council Prosperity Partnership award.
It is another example of British scientific expertise being brought together with industry and some of the country’s most advanced research facilities to tackle major real-world problems.
Understanding how disinfectants actually work
Disinfectants play an important role in preventing infections in hospitals, workplaces, public buildings and homes.
Effective cleaning can reduce cross-contamination and the spread of infectious disease, potentially helping to reduce hospitalisations and the need for antibiotic treatment.
Yet despite the enormous quantities of disinfectant products used around the world, scientists say there is still much to learn about precisely how their individual ingredients interact with microbes at the molecular level.
The researchers examined two representative disinfectant surfactants, didecyldimethyl ammonium chloride, known as DDAC, and hexaethylene glycol monododecyl ether, or C12E6.
They tested the substances separately and together against Gram-negative bacteria, a group which includes E. coli.
Scientists then used advanced neutron techniques to examine how the substances interacted with model bacterial membranes.
Experiments were conducted using instruments at the ISIS Neutron and Muon Source, part of the UK’s Science and Technology Facilities Council, as well as neutron reflectivity experiments at the Institut Laue-Langevin.
The team also worked closely with the ISIS deuteration laboratory, using selective deuteration techniques to build a detailed picture of what was happening within the outer and inner bacterial membranes.
Combination produced stronger effect
The scientists found C12E6 attached to the outer membrane of E. coli and partially entered its inner membrane. On its own, however, it caused only relatively mild destabilisation and did not significantly disrupt the membrane.
DDAC behaved differently.
It strongly bound to and penetrated both the outer and inner membranes, causing leakage and cellular damage, which helps explain its effectiveness as a disinfectant.
Crucially, researchers discovered that combining the two substances could improve the process.
C12E6 helped DDAC insert into the bacterial membrane, increasing disruption. However, the scientists also found that the balance between the ingredients matters, because excessive amounts of C12E6 slowed DDAC’s bacteria-killing action.
The findings could therefore help scientists and manufacturers understand not simply which ingredients kill bacteria, but how different ingredients can be combined in carefully formulated products to achieve the best results.
Helping the fight against antimicrobial resistance
Professor Jian Lu, lead author of the study, said the molecular interactions revealed by the experiments were helping researchers understand the different roles played by surfactants within formulated products.
He said connecting their membrane-disrupting behaviour with their antimicrobial effectiveness could help pave the way for new product formulations in the fight against antimicrobial resistance.
Antimicrobial resistance, or AMR, occurs when microorganisms such as bacteria evolve so that medicines designed to kill them become less effective. It is regarded as a major global health challenge, making research into infection prevention and effective disinfection increasingly important.
Dr Jordan Petkov, Director Strategic Projects and External Research at Arxada, said access to Britain’s cutting-edge scientific infrastructure had been “absolutely critical” to the work.
He said collaboration with scientists at the STFC’s ISIS facility had provided invaluable insight into how biocides work at the most fundamental level and helped the researchers test their hypotheses.
The partnership is now set to continue, bringing together The University of Manchester, industry and UK Research and Innovation facilities to investigate one of the most pressing scientific and societal challenges facing the world.
The study has been published in the Journal of Colloid and Interface Science.
From Manchester’s researchers to the world-class neutron facilities at ISIS, the work demonstrates the formidable scientific capability Britain possesses when its universities, industry and national laboratories combine their expertise.
At a time when antimicrobial resistance poses an increasing international challenge, British science is once again helping to provide the knowledge that could underpin the technologies and products of the future.
