Science Tokyo discovers new lactic acid bacteria from shibazuke

A new lactic acid bacterium has been found in shibazuke, a traditional pickle from Kyoto. The discovery was made by a research team consisting of Professor Takuji Yamada from the School of Life Science and Technology, Institute of Science Tokyo and Dr. Kazunori Sawada from Gurunavi. The newly discovered Lactiplantibacillus plantarum KY5-ES5 produces a novel type of exopolysaccharide (EPS) containing glycerol. EPS are important components related to "viscosity" and "smoothness" in foods. These findings were published in Scientific Reports.

The research team used synthetic medium to culture the strain, avoiding the influence of natural product-derived components in the medium, and conducted detailed analysis of the EPS produced by this strain. First, high-performance liquid chromatography revealed that the EPS was composed of monosaccharides such as glucose, galactose, and glycerol in a ratio of approximately 6:3:1. There have been almost no reports of EPS containing glycerol in this way. Furthermore, NMR analysis confirmed that in this EPS, the monosaccharides are connected by various bonding patterns, and that it has a branched structure and glycerol phosphate modifications. This distinctive structure suggested that the EPS has the potential to create high viscosity and smooth texture.

The newly identified EPS can naturally improve the texture of plant-based yogurts and fermented beverages, leading to improved quality in fermented foods. Because it can add viscosity and smoothness without using chemical additives, it could also contribute to the development of clean label foods that value additive-free products, for which demand has been growing in recent years. Furthermore, since the EPS produced by this lactic acid bacterium has a structure that has not previously been reported, in the future it can be found to possess new functionalities such as immunomodulatory effects and antioxidant effects, becoming an important foundation for the functionality of fermented foods.

From now on, the functions of the newly discovered EPS will be further researched to explore whether it has effects such as regulating the intestinal environment, alleviating oxidative stress, and/or balancing immunity. The researchers also aim for industrial applications to plant-based fermented beverages and alternative dairy products.

Journal Information
Publication: Scientific Reports
Title: A novel glycerol-containing exopolysaccharide from the ropy strain Lactiplantibacillus plantarum KY5-ES5 and its impact on medium viscosity
DOI: 10.1038/s41598-025-29706-8