Bioactive compounds with possible industrial applications are identified in extremophilic bacteria from the Andes

Researchers isolated a strain of Pseudomonas alcaligenes that can withstand temperatures as high as 44 °C from a hot spring in Chile, and characterized the substances produced by the bacterium that help it survive extreme conditions.

By Thais Szegö  |  Agência FAPESP – An article published in the journal Scientific Reports describes how researchers analyzed biofilm produced by bacteria found in the El Medano hot springs, located in Chile in the central Andes, and concluded that one of its key ingredients can be used to develop natural additives for the pharmaceutical and food industries. 

The biofilm ingredient in question is an exopolysaccharide (EPS), a cluster of extracellular carbohydrate polymers produced by the thermotolerant Med1 strain of the bacterium Pseudomonas alcaligenes, which grows in the 34 °C-44 °C temperature range. The EPS protects the bacterium’s cells in the inhospitable environment of its habitat, characterized by high temperatures, acidic pH values, and elevated concentrations of metals. 

With demand for natural bioactive compound growing in several industries, research on EPSs has intensified owing to structural and functional properties that offer valuable alternatives to synthetic additives. Microbial EPSs also have several advantages over plant-derived polysaccharides, including a much wider array of physicochemical properties and biological activities. 

These include antiviral, antitumor, immunoregulatory, antioxidant and emulsifying effects. The EPSs are also good at flocculation – facilitating the aggregation of small particles in a liquid or solution to form larger clusters. Given all these benefits, the EPSs receive ample attention from the food, cosmetics, biomedical, biomaterials and wastewater treatment industries.

Studying structures derived from extremophilic bacteria (able to thrive under environmental conditions that are extreme for most living beings, in terms of pressure, acidity, salinity, heat etc.) is a way to understand them better and create opportunities to derive novel resources from these substances with biotechnological applications.

“We chose to study the hot springs in the central Chilean region of Maule because they are relatively unexplored in terms of biotechnological aspects of the value-added bioactive compounds produced by bacteria as part of their resistance to the stress caused by factors in the environment they inhabit,” said João Paulo Fabi, a professor in the Department of Food and Experimental Nutrition at the University of São Paulo’s School of Pharmaceutical Sciences (FCF-USP) in Brazil, and a co-author of the article. 

The first part of the study – conducted in partnership by Brazilian, Chilean, American and Iraqi researchers, with the support of the Food Research Center (FoRC), one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP – consisted of isolating the bacterium from a water sample collected from the hot springs, sequencing its genome, and experimenting with optimization of EPS production at a high temperature to confirm its thermotolerance. 

The isolated strain was found to tolerate 44 °C, with an optimum growth temperature of 37 °C. This is good news, according to the researchers, because unwanted microorganisms cannot grow at this high temperature during the EPS production process.

The second part of the study comprised physical and chemical characterization of the EPS and a functional analysis with a view to its technological application by the food and pharmaceutical industries. As part of this stage, Aparna Banerjee, a professor at the Autonomous University of Chile, visited Fabi’s lab with the support of Chile’s National Fund for Scientific and Technological Development (Fondecyt). “The study concluded that the EPS produced by P. alcaligenes Med1 has unique structural properties and thermal stability, as well as exhibiting significant antioxidant, emulsification and flocculation activity, making it suitable for potential applications by the food and pharmaceutical industries as a natural additive,” Fabi said. 

The exclusive structural data obtained via genome sequencing and analytical studies also provides a basis for exploring other extremophilic bacterial EPSs with similar applications. “Although more tests and regulatory approvals are needed for commercial use, this EPS displays strong potential as a natural alternative to synthetic additives, especially in applications that require thermal stability and biocompatibility,” he said. 

Also according to Fabi, the results of the research also offer a model for optimizing EPS production and new perspectives on the bioactivity of this compound, potentially leading to the development of sustainable or ecofriendly additives for various sectors, including the food, cosmetics and pharmaceutical industries. 

The article “Unveiling a novel exopolysaccharide produced by Pseudomonas alcaligenes Med1 isolated from a Chilean hot spring as biotechnological additive” is at: www.nature.com/articles/s41598-024-74830-6.