# Developing a Novel Fermented Milk with Anti-Aging and Anti-Oxidative Properties Using Lactobacillus kefiranofaciens HL1 and Lactococcus lactis APL015

## TL;DR

A new fermented milk using two bacteria strains improves cognitive function and reduces aging and oxidative stress in mice.

## Contribution

A co-culture of L. kefiranofaciens HL1 and L. lactis APL015 enhances fermented milk viability and health benefits.

## Key findings

- FM improved cognitive behavior and reduced oxidative damage in aging mice.
- FM lowered inflammation and increased antioxidant enzyme activity in the brain.
- FM increased short-chain fatty acid producers and cecal butyrate while reducing harmful gut bacteria.

## Abstract

Background/Objectives: Lactobacillus kefiranofaciens HL1, isolated from kefir, exhibits antioxidant and anti-aging activities, defined here as improved cognitive function and reductions in oxidative stress and inflammatory markers. However, its poor milk viability limits application. This study developed a novel fermented milk by co-culturing HL1 with Lactococcus lactis subsp. cremoris APL015 (APL15) to enhance fermentation and health benefits. Methods: HL1 and APL15 were co-cultured to produce fermented milk (FM), and fermentation performance, microbial viability, texture, and syneresis were evaluated. A D-galactose-induced aging BALB/c mouse model was used to assess cognitive function, oxidative stress, inflammation, antioxidant enzyme activity, and gut microbiota after 8 weeks of oral administration. Results: FM reached pH 4.6 within 16 h, with high viable counts (~109 CFU/mL) for both strains. HL1 viability and texture were maintained, with smooth consistency and low syneresis. In vivo, FM improved cognitive behavior (Y-maze, Morris water maze), reduced oxidative damage (MDA), lowered IL-1β and TNF-α, and enhanced brain SOD levels. FM-fed mice exhibited increased short-chain fatty acid producers, higher cecal butyrate, and reduced Clostridium perfringens. Conclusions: The co-cultured fermented milk effectively delivers HL1 and provides antioxidant, anti-inflammatory, and anti-aging effects in vivo, likely via gut–brain axis modulation. It shows promise as a functional food for healthy aging.