# Genomic Insights into Probiotic Lactococcus lactis T-21, a Wild Plant-Associated Lactic Acid Bacterium, and Its Preliminary Clinical Safety for Human Application

## TL;DR

This paper explores the genome and safety of Lactococcus lactis T-21, a wild plant-associated probiotic bacterium, showing it has unique traits and is safe for human use.

## Contribution

The study provides the first detailed genomic and clinical safety analysis of the wild Lactococcus lactis T-21 strain.

## Key findings

- Genomic analysis revealed T-21's ability to metabolize diverse plant carbohydrates and produce exopolysaccharides and nisin.
- Preliminary clinical trials showed no adverse effects from consuming T-21-fermented milk in healthy adults.
- T-21's wild plant origin contributes to its metabolic versatility and distinct probiotic properties compared to dairy strains.

## Abstract

Lactococcus lactis T-21 is a lactic acid bacterium isolated from wild cranberries in Japan that demonstrates significant immunomodulatory properties and has been incorporated into commercial health products. However, probiogenomic analyses specific to T-21 have remained largely unexplored. This study performed a thorough genomic characterisation of T-21 and evaluated its safety in initial clinical trials. Genomic analysis revealed substantial genetic diversity and metabolic capabilities, including enhanced fermentative potential demonstrated by its ability to metabolise a wide range of plant-derived carbohydrates, and genetic determinants associated with exopolysaccharide biosynthesis and nisin production, distinguishing T-21 from domesticated dairy strains. These attributes, reflective of its wild plant origin, may contribute to its metabolic versatility and unique probiotic functionalities. A preliminary clinical trial assessing the safety of T-21-fermented milk in healthy Japanese adults indicated no significant adverse outcomes, corroborating its safety for human consumption. Together, these findings support the feasibility of utilising non-dairy, wild plant-origin strains in dairy fermentation processes as probiotics. This study expands our understanding of the genomic basis for T-21’s probiotic potential and lays the groundwork for further investigations into its functional mechanisms and potential applications in promoting human health.