New, biological, and safer soaps

Surfactants are synthesized from petroleum and are the main active ingredient in most soaps, detergents, and shampoos. Biosurfactants, produced by bacteria, are safer and can replace synthetic surfactants.

Rhamnolipid molecules are some of the safest surfactants known and are particularly attractive, thanks to their biodegradability, minimal toxicity, and amenability to be produced from industrial waste. But there's a problem. They are made using Pseudomonas aeruginosa, a pathogenic bacterium harmful to humans.

"If we want to fully gain the benefits of rhamnolipids, we need to grow these pathogenic bacteria on a huge scale. And because that's a health risk, the industry is looking for alternatives," explained Professor Gauthier. The molecules produced by these bacteria are usually mixed with other compounds or virulence factors, making them trickier to use.

To address the problem, the research team identified molecules that resemble rhamnolipids in Pantoea ananatis, a non-pathogenic bacterium. The team was then able to chemically synthesize these molecules, called ananatosides, in the laboratory, raising the possibility that they could be produced on a larger scale than using bacteria. The industry is already showing interest in these promising new biosurfactants.

A look at the structure

The new molecule comes in two different forms, A and B. Ananatoside A structure is described as closed, while B is open. The molecule A is closed in on itself to form a loop. The process that closes the loop is called lactonization, and it has also been achieved with rhamnolipids to create new molecules.

The team has shown that the lactonized form has a large impact on the biological action of the molecules. It minimizes the surface-active properties of rhamnolipids and renders them toxic.

Now the researchers want to characterize further new biosurfactants and make the molecules more stable.

An interdisciplinary team

INRS professor Éric Déziel helped with the research as an expert on biosurfactants. His team produced and isolated ananatosides produced naturally from the bacteria Pantoea.

Mayri Alejandra Dìaz De Rienzo, a lecturer at the Liverpool John Moores University in England, also took part as an INRS guest professor. Her expertise in the fermentation and downstream processing of biosurfactants helped the team identify the surface-active properties of these new biosurfactants.

Maude Cloutier, a PhD student and recipient of a Vanier Canada Graduate Scholarship, and Marie-Joëlle Prévost, a recipient of a summer scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC), aided the team with their chemical synthesis work in the laboratory.