IISc researchers discovered CRhAB, a cow rumen enzyme that breaks down up to 95% of a bacterial biofilm’s polysaccharide matrix, weakening two WHO-priority antibiotic-resistant pathogens.
Researchers at the Indian Institute of Science (IISc) have identified an enzyme from cow gut microbes that can break down the protective polysaccharide matrix of bacterial biofilms — a discovery that could offer a new angle of attack against some of the world’s most stubborn antibiotic-resistant infections. The findings were published in npj Biofilms and Microbiomes (2026).
Why Biofilms Are So Hard to Treat
The research targets Acinetobacter baumannii, a bacterium the World Health Organization classifies as a critical priority pathogen. It readily forms biofilms on wounds and medical surfaces, contributing to persistent infections and delayed healing, and many current treatments are ineffective against it. Biofilms are communities of bacteria encased in a matrix of polysaccharides, proteins, lipids, and extracellular DNA that forms a physical barrier — reducing how well antimicrobials and the body’s own immune cells can penetrate and act.
Where the Enzyme Comes From: A Cow’s Rumen
The IISc team turned to an unusual source for a solution: the bovine rumen, or cow gut. Using genomic data from rumen microbes, researchers identified enzymes capable of digesting cellulose — a polysaccharide that’s also abundant in a cow’s diet. “Polysaccharides are one of the major components [of bacterial biofilms], constituting between 45% and 95%,” explained Debasis Das, Associate Professor at IISc’s Department of Inorganic and Physical Chemistry and co-corresponding author on the study. These polysaccharides cross-link with each other, giving biofilms much of their structural strength.
One Enzyme, Two Dangerous Pathogens
The team’s key discovery is an enzyme they’ve named CRhAB — Cow rumen hydrolase against A. baumannii. It proved highly effective against biofilms formed by both A. baumannii and a second pathogen, Klebsiella pneumoniae, drastically reducing biofilm formation and suppressing the expression of key biofilm-related genes in both bacteria. “Both A. baumannii and K. pneumoniae are among the most notorious of the ESKAPE pathogen group, and thankfully, this enzyme acts against both. It’s a dual bacterial strategy with one enzyme,” said Dipshikha Chakravortty, Professor at IISc’s Department of Microbiology and Cell Biology and co-corresponding author. Critically, the researchers describe the approach as weakening the bacteria’s defenses rather than directly killing them — a mechanism they say could help restore the effectiveness of existing antibiotics while reducing the selective pressure that drives further resistance.
From Lab Dish to a Wound Dressing
To test a real-world application, the team developed a medical gauze with the CRhAB enzyme imbibed in it and evaluated it in a mouse wound infection model. Reshma Ramakrishnan, former PhD student at IISc and the study’s first author, noted a practical challenge in the process: “Maintaining the enzyme-immobilised gauze over the wound throughout the study was particularly difficult because the mice naturally tried to remove the dressing. We had to optimise the experimental setup to ensure that the gauze remained in place while minimising stress to the animals.”
What’s Next: Diabetic Foot Infections and an Inhalable Formulation
The research is still in its early stages, and the team has outlined several directions for future work: a patch-like wound dressing aimed at treating difficult infections such as diabetic foot infections, delivery systems for respiratory infections including those caused by K. pneumoniae, and the possibility of combining multiple enzymes to target a broader range of biofilm-forming pathogens. The team’s longer-term ambition is even more specific. “A long-term goal is to develop an inhalable or nebulisable CRhAB formulation that delivers the enzyme directly to the lungs, thereby preventing biofilm formation and disrupting established biofilms,” Ramakrishnan said. “Such a localised, non-invasive approach could offer a promising new treatment for chronic A. baumannii respiratory infections.”