Lactobacillus reuteri AN417 cell-free culture supernatant as a novel antibacterial agent targeting oral pathogenic bacteria

Kyung Mi Yang,Ji-Sun Kim,Jeong-Kyu Oh,Doo-Sang Park,Hye-Sung Kim,Young-Youn Kim,Kwang-Hak Bae,Hye-Won Jung

doi:10.1038/s41598-020-80921-x

Kyung Mi Yang, Ji-Sun Kim + Show 6 more

Open Access

https://doi.org/10.1038/s41598-020-80921-x

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Abstract

Lactobacillus reuteri AN417 is a newly characterized probiotic strain. The activity of AN417 against oral pathogenic bacteria is unknown. We investigated the antibacterial activity of cell-free L. reuteri AN417 culture supernatant (LRS) against three oral pathogens: Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans. P. gingivalis and F. nucleatum have been implicated in periodontal disease, whereas S. mutans causes dental caries. Exposing these oral pathogenic bacteria to LRS significantly reduced their growth rates, intracellular ATP levels, cell viability, and time-to-kill. The minimal inhibitory volume of LRS was 10% (v/v) against P. gingivalis, 20% (v/v) for F. nucleatum, and 30% (v/v) for S. mutans. LRS significantly reduced the integrity of biofilms and significantly suppressed the expression of various genes involved in P. gingivalis biofilm formation. The L. reuteri AN417 genome lacked genes encoding reuterin, reuteran, and reutericyclin, which are major antibacterial compounds produced in L. reuteri strains. LRS treated with lipase and α-amylase displayed decreased antibacterial activity against oral pathogens. These data suggest that the antibacterial substances in LRS are carbohydrates and/or fatty acid metabolites. Our results demonstrate that LRS has antimicrobial activity against dental pathogenic bacteria, highlighting its potential utility for the prevention and treatment of P. gingivalis periodontal disease.

Highlights

Lactobacillus reuteri AN417 is a newly characterized probiotic strain
The results showed that L. reuteri AN417 displayed the strongest antibacterial activity against pathogens
The findings indicated that cell-free culture supernatant derived from L. reuteri AN417 exhibited the highest activity against P. gingivalis and potentially against other oral pathogenic bacteria

Summary

Introduction

Lactobacillus reuteri AN417 is a newly characterized probiotic strain. The activity of AN417 against oral pathogenic bacteria is unknown. P. gingivalis and F. nucleatum have been implicated in periodontal disease, whereas S. mutans causes dental caries Exposing these oral pathogenic bacteria to LRS significantly reduced their growth rates, intracellular ATP levels, cell viability, and time-to-kill. P. gingivalis and F. nucleatum are Gram-negative and obligate anaerobes that cause periodontal d iseases[7,8] These two oral pathogens degrade collagen, induce halitosis, and produce endotoxins, such as lipopolysaccharides (LPS), which destroy alveolar bone and cause tooth loss[9]. S. mutans produces acidic compounds and plays an important role in the formation of biofilms on teeth, which cause dental c aries[10] These oral pathogens can penetrate directly into the vascular endothelial cells or enter damaged blood vessels and adhere to specific organs, leading to systemic disease[11]. A recent review highlighted potential antimicrobial agents, including those produced by lactic acid bacteria, for the treatment of dental d iseases[4]

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