# Lactic acid bacteria isolated from mammalian feces exhibit distinct diversity and probiotic traits

## TL;DR

Lactic acid bacteria from mammal feces show unique diversity and probiotic effects, including increased longevity in worms.

## Contribution

The study identifies LAB from diverse mammals and demonstrates their probiotic potential through modulation of stress pathways in C. elegans.

## Key findings

- Lactic acid bacteria from piglets increased C. elegans lifespan by 42.9%.
- LAB strains activated the DAF-16/FOXO pathway, enhancing stress resistance in worms.
- Specific LAB strains increased expression of stress-related genes like sod-3 and gcs-1.

## Abstract

Lactic acid bacteria (LAB) play an essential role in mammalian gut health and are promising candidates for probiotic use. In this study, we have identified LAB isolated from fecal samples of bats, calves, cats, or piglets or from the vaginal mucosa or teat skin of a lactating sow. Specifically, we identified 98 lineages belonging to the phyla Bacillota, Pseudomonadota, or Actinomycetota. Enterococcus faecalis was the only species common to all mammal groups. The LAB communities were functionally different depending on the host they originated from. Caenorhabditis elegans fed with Lactiplantibacillus plantarum PA27 lived 42.9% longer than C. elegans fed with Escherichia coli OP50. Additionally, C. elegans worms fed with L. plantarum PA17 or PA19 had longer body length than C. elegans worms fed with E. coli OP50. L. plantarum PA17, PA19, and PA27, isolated from piglets, were selected to evaluate how the signaling pathway (DAF-16/FOXO) was modulated during regulation of oxidative and thermal stress-related genes (sod-3, hsp-16.2, and gcs-1). The proportion of C. elegans with nuclear DAF-16 increased among worms fed with L. plantarum PA17, PA19, or PA27 (40% to 96%) compared to worms fed with the E. coli OP50 control (22%). The sod-3 and gcs-1 genes were more expressed in C. elegans fed with L. plantarum PA27. These results highlight that LAB isolated from mammals are potentially effective probiotics that can modulate responses to oxidative stress by activating the DAF-16/FOXO pathway, which promotes gut health and longevity.

The online version contains supplementary material available at 10.1007/s11274-026-04801-8.