# Oral Administration of Freeze‐Dried Lactobacillus zeae Alleviates Periodontitis by Affecting the Oral and Intestinal Flora

## TL;DR

This study shows that freeze-dried Lactobacillus zeae N165 can reduce periodontitis in animals by improving oral and gut bacteria and reducing inflammation.

## Contribution

The novel contribution is identifying Lactobacillus zeae N165 as an effective oral probiotic that alleviates periodontitis through specific microbial and metabolic mechanisms.

## Key findings

- Lactobacillus zeae N165 inhibits harmful bacteria like Fusobacterium nucleatum and Porphyromonas gingivalis in vitro.
- Freeze-dried L. zeae N165 reduces alveolar bone resorption and pro-inflammatory markers in periodontitis-affected rats.
- The probiotic modulates oral and intestinal microbiota and affects metabolic pathways like glutamine degradation and biotin metabolism.

## Abstract

Due to the high incidence of periodontal diseases in pet cats and dogs, the purpose of this study is to screen bacteria with beneficial oral health effects and assess the effectiveness of its freeze‐dried cell. In this study, we explored the effects of oral probiotics by determining the bacteriostatic ability, percentages of self‐aggregation and co‐aggregation in vitro, and through microbial community analysis, the alleviating effect of freeze‐dried cells on periodontitis and its mechanism of action were evaluated.
Lactobacillus zeae N165 significantly inhibited
Fusobacterium nucleatum
and
Porphyromonas gingivalis
, and it had high co‐aggregation rates of 96.78% and 88.94% with
F. nucleatum
and
P. gingivalis
, respectively. In vivo, freeze‐dried
L. zeae N165 cells significantly reduced alveolar bone resorption, TNF‐α, and IL‐6 levels in rats with periodontitis, maintained a healthy oral and intestinal microbial community structure, and regulated the dominant species to alleviate periodontitis. The prediction of functions by the KEGG database analysis of oral flora revealed that freeze‐dried
L. zeae N165 cells may alleviate periodontitis via four pathways: reduction of glutamine degradation, modulation of lipopolysaccharide levels, biosynthesis of polyketide glycan units, and biotin metabolism.
L. zeae N165 showed promising results in both in vitro and in vivo experiments, suggesting new directions for the oral probiotics industry.

First, probiotic strain
Lactobacillus zeae N165 with oral antibacterial activity, autoaggregation ability and coaggregation ability was screened through in vitro experiments. Then, in vivo efficacy evaluation was conducted on this strain, and a mouse model was used to verify its ameliorative effect on periodontitis. The results demonstrated that this strain could alleviate alveolar bone resorption, reduce the levels of pro‐inflammatory factors TNF‐α and IL‐6, maintain the structural stability of oral and intestinal microbiota, and regulate the composition of dominant bacterial species. To further explore the potential metabolic and molecular mechanisms underlying the alleviation of periodontitis by
Lactobacillus zeae N165, KEGG pathway analysis was performed. It was found that this process was mediated by reducing glutamine degradation, regulating lipopolysaccharide levels, biosynthesizing polyketide units, and metabolizing biotin.