Modulation of the salivary microbiome using deep-sea marine bacterial strains: A pilot study

Background

The oral microbiome is a critical determinant of both local and systemic health. Dysbiosis, particularly the overgrowth of pathogenic taxa, is implicated in various oral diseases and may contribute to extraoral inflammatory conditions. Although probiotics derived from gut commensals have shown some efficacy, their application to the oral cavity is limited by environmental incompatibility. Marine bacteria, especially those adapted to extreme environments, offer a novel therapeutic avenue due to their inherent antimicrobial and biofilm-disruptive properties.

Aim

This pilot study investigated the potential of deep-sea marine bacterial strains—Marinobacter hydrocarbonoclasticus and Pseudoalteromonas spp.—to modulate the salivary microbiome by suppressing oral pathogens and enriching beneficial commensal species.

Methods

A randomized, controlled, two-arm parallel design was employed involving 20 healthy adult participants. Subjects were assigned either to a Treatment Group (n = 10), receiving a marine-derived bacterial mouthwash for seven days, or a Control Group (n = 10) with no intervention. Unstimulated saliva samples were collected at baseline and post-intervention. Microbial profiling was conducted using 16S rRNA gene sequencing and species-specific quantitative PCR. Analyses included paired t-tests, Principal Component Analysis (PCA), and microbial network inference to assess changes in microbial abundance and community structure.

Results

The Treatment Group demonstrated statistically significant reductions in Streptococcus mutans and Porphyromonas gingivalis (p < 0.001 for both), alongside increases in Streptococcus sanguinis and Veillonella spp. (p < 0.001). PCA revealed a distinct shift in microbial composition post-treatment, with clustering patterns not observed in the Control Group. Co-occurrence network analysis indicated a restructuring of microbial interactions, suggestive of a shift toward a more stable and health-associated microbiome.

Conclusion

The application of marine-derived bacterial strains was associated with favorable modulation of the oral microbiome, including suppression of key pathogens and enhancement of beneficial taxa. While preliminary, these findings highlight the therapeutic promise of marine probiotics as a biologically selective and ecologically supportive approach to oral health. Larger, placebo-controlled studies are warranted to confirm efficacy, assess long-term effects, and evaluate clinical outcomes.