Lactobacillus rhamnosus GG as Biosensor for Oral and Systemic Health Conditions: A Pilot Study

Early disease detection using biosensors is a significant challenge in modern medicine. This study aimed to investigate Lactobacillus rhamnosus GG (LGG) as a bacterial biosensor for biomarkers indicative of oral and systemic health conditions. For this purpose, LGG was cultured and then exposed to phosphate buffer, 10 wt.% sucrose solution, pH = 4.0, lactic acid, and filter-sterile saliva from five subjects. A total of 10 groups consisted of filter-sterile, freshly pooled saliva of subject 1 (SANT), subject 2 (SLAN), subject 3 (SLFU), subject 4 (SLPA), subject 5 (SLPO), phosphate buffer solution (pH = 7.4, BUF), and PBS with resin. Subsequently, the proteomic profiling of the samples was done by high-resolution mass spectrometry, focusing on the expression of bacterial proteins. The samples were evaluated for the biosensing capacity of LGG through its proteomic expression. Statistical comparisons were performed to outline proteomic changes, clustering upregulated and downregulated proteins relevant to stress response, metabolism, and environmental adaptation. The identification of key proteins associated with metabolic regulation, response to oxidative stress, and bacterial adaptation was possible using heatmaps and volcano plots. Each subject’s salivary composition also presented its unique, characteristic proteomic signature. Results showed a massive downregulation of proteins linked with stress under nutrient-rich conditions. In conclusion, the early detection of protein expression modifications related to environmental niche changes has shown that LGG can serve as a promising novel diagnostic tool, potentially overcoming many drawbacks of current physicochemical transducer-based biosensors.