Researchers unlock kefir’s hidden potential for sustainable biopolymer production
A team of Brazilian researchers from the Federal University of Pelotas has successfully optimized the production of exopolysaccharides (EPS) — natural biopolymers produced by lactic acid bacteria (LAB) — isolated from traditional kefir grains. Their findings, published in European Food Research and Technology, could reshape how we design functional foods and biotechnological materials.
What are exopolysaccharides, and why do they matter?
Exopolysaccharides are long-chain carbohydrate molecules synthesized by beneficial bacteria such as Leuconostoc and Pediococcus species.
They are known for their immunomodulatory, antioxidant, and antimicrobial properties, and are widely used as natural thickeners, stabilizers, and texture enhancers in fermented foods. Beyond food, they also hold promise in pharmaceuticals, cosmetics, and environmental applications such as heavy-metal removal.
Kefir: a natural source of beneficial bacteria
Kefir, a fermented milk beverage, is rich in diverse microbial communities — lactic acid bacteria, acetic acid bacteria, and yeasts — coexisting in a symbiotic matrix called kefir grains.
These grains not only produce the beverage’s characteristic texture and tang but also harbor EPS-producing strains capable of improving gut health and food quality.
From five kefir samples, the team isolated 44 LAB strains, of which eight were microbiologically safe and efficient EPS producers.
Meet the standout strain: Leuconostoc mesenteroides KLM6
Among the isolates, Leuconostoc mesenteroides KLM6 showed exceptional potential.
By fine-tuning its growth conditions — pH and temperature — the researchers achieved a 105.1% increase in EPS yield, reaching 0.841 g/L, compared to initial standard fermentation parameters.
The breakthrough came from identifying the optimal combination of pH 5.0 and 50.5 °C, which triggered stress responses enhancing EPS synthesis.
“Environmental stress can act as a driver for exopolysaccharide production.”
“This understanding allows for scalable, cost-effective production of biopolymers using safe, food-grade bacteria.”
Ensuring safety and functionality
All EPS-producing isolates were evaluated for antimicrobial resistance, enzyme activity, and hemolytic potential to confirm food safety.
Most were classified as GRAS (Generally Recognized As Safe), with no virulence genes detected.
Carbohydrate fermentation tests revealed that the majority of isolates were heterofermentative, producing lactic acid, ethanol, and CO₂ — a desirable feature for balanced flavor and texture in dairy fermentation.
Industrial promise and environmental relevance
The optimized EPS yield suggests industrial feasibility without expensive supplements or additives.
Such biopolymers could replace synthetic thickeners and emulsifiers, reducing environmental impact while supporting clean-label food innovation.
“Kefir grains represent a sustainable reservoir of functional microorganisms,”
“Harnessing them for EPS production can contribute to greener, more natural product formulations.”
Key findings
- 44 LAB isolates obtained from kefir; 8 produced EPS safely.
- Leuconostoc mesenteroides KLM6 achieved the highest yield (0.841 g/L).
- Optimized conditions: pH 5.0, 50.5 °C, 24 hours.
- Yield increased by 105% compared with standard fermentation.
- EPS confirmed by presence of glycosyltransferase (GT) gene.
Applications and future directions
The study demonstrates that controlling pH and temperature stress can significantly boost EPS productivity.
Future research could explore scaling up fermentation systems and testing EPS functionality in real food matrices like yogurts and probiotic drinks.
This discovery paves the way for developing natural texture enhancers and functional food ingredients that align with current sustainability and health trends.
Reference
Bierhals, C. K., Siqueira, M. F. F., de Souza Sigali, S., Kroning, I. S., de Lima Costa, I. H., Massaut, K. B., Lopes, G. V., da Silva, W. P., & Fiorentini, Â. M. (2025). Exopolysaccharides produced by lactic acid bacteria from kefir: production and optimization of cultivation conditions. European Food Research and Technology. https://doi.org/10.1007/s00217-025-04920-w
