Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 01, 2026 53 minutes ago
Dental News: Researchers have identified a newly emerging strain of beneficial oral bacteria that could help protect teeth and gums while maintaining a healthier balance of microbes inside the mouth. The newly studied bacterium, known as Streptococcus salivarius G7, has demonstrated impressive safety and oral health benefits, raising hopes that it could become a next-generation probiotic specifically designed for oral care.
Scientists discover a promising new oral probiotic that can suppress harmful dental bacteria while helping maintain a
healthy balance of microbes in the mouth
The research was conducted by scientists from the Division of Regenerative and Reconstructive Sciences, School of Dentistry, University of California Los Angeles (UCLA), USA, and the Department of Oral Microbiology and Immunology, College of Dentistry, Dankook University, Republic of Korea.
A Friendly Bacterium Already Living in the Mouth
Unlike many probiotics that originate from the gut, Streptococcus salivarius is naturally one of the earliest bacterial species to colonize the human mouth. It is considered a normal resident of the oral environment and plays an important role in preventing harmful microbes from gaining a foothold.
Scientists have long been interested in certain strains of S. salivarius because they can produce natural antibacterial compounds called bacteriocins. These compounds act like microscopic weapons that suppress disease-causing bacteria without disturbing the entire microbial ecosystem.
The newly discovered G7 strain was isolated from the mouth of a healthy adult and subjected to extensive genetic and laboratory testing to determine whether it could be safely developed as an oral probiotic.
Extensive Safety Testing Shows Promising Results
One of the most important requirements for any probiotic is safety. The researchers performed whole-genome sequencing and detailed biological analyses to ensure that the G7 strain did not possess characteristics that could be harmful to humans.
The genetic analysis confirmed that the strain did not contain virulence factors that might cause disease. Importantly, it also lacked transferable antibiotic-resistance genes, reducing concerns that it could contribute to the growing global problem of antibiotic resistance.
The bacterium was also tested against multiple antibiotics commonly used in medicine. Results showed that its resistance levels remained well below internationally accepted safety limits.
Further tests demonstrated very low toxicity toward both oral cells and intestinal cells. Researchers also found that the strain did not produce D-lactate, a compound that can contribute to serious metabolic complications in certain vulnerable individuals.
Less Acid Means Less Risk of Tooth Decay
One of the key findings involved acid production. Tooth decay develops when oral bacteria produce acids that gradually dissolve tooth enamel. The notorious cavity-causing bacterium Streptococcus mutans is particularly effective at creating highly acidic conditions.
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When researchers compared the two bacteria, they discovered that S. salivarius G7 produced significantly less acid. After 12 hours of growth, the cavity-causing S. mutans reduced environmental pH to approximately 3.5, while the G7 strain maintained a much milder pH of about 5.38.
This difference is important because enamel begins to demineralize at around pH 5.5. The findings suggest that G7 is far less likely to contribute to tooth decay and may help preserve a healthier oral environment.
Strong Activity Against Harmful Oral Pathogens
Perhaps the most exciting discovery was the strain's ability to inhibit several bacteria associated with oral diseases.
Laboratory experiments showed that substances produced by S. salivarius G7 significantly suppressed the growth of several dangerous microbes, including Streptococcus mutans, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Enterococcus faecalis. These bacteria are commonly linked to cavities, gum disease, periodontal infections, and root canal-related infections.
In several tests, the G7 strain actually displayed stronger antimicrobial activity than a standard reference strain of S. salivarius, highlighting its potential therapeutic value.
Helping Restore Balance in Oral Biofilms
The human mouth contains more than 700 different microbial species that exist together in complex communities called biofilms. Oral diseases often emerge when this delicate ecosystem becomes unbalanced.
In experiments using biofilms created from human saliva samples, researchers found that adding S. salivarius G7 significantly reduced populations of Streptococcus mutans while preserving overall beneficial bacterial communities.
This
Dental News report highlights an increasingly important concept in oral health research: instead of simply killing bacteria, scientists are now seeking ways to restore microbial balance. The G7 strain appeared capable of supporting this balance by selectively reducing harmful organisms without disrupting the wider oral ecosystem.
Conclusions
The findings suggest that Streptococcus salivarius G7 could become an important new probiotic for oral health. The strain successfully passed a wide range of safety evaluations, including genetic screening, antibiotic susceptibility testing, toxicity assessments, and metabolic analyses. Beyond safety, it demonstrated several desirable oral health properties, including low acid production, potent activity against disease-causing bacteria, and the ability to help maintain a balanced oral microbiome. By reducing cavity-associated bacteria while preserving beneficial microbial communities, the strain may offer a more natural and sustainable approach to preventing dental disease. Although larger human clinical studies will still be needed, the evidence so far indicates that G7 is a highly promising candidate for future oral probiotic products aimed at improving dental and gum health.
The study findings were published in the peer reviewed journal: Microorganisms.
https://www.mdpi.com/2076-2607/14/6/1234
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