# _Lactobacillus rhamns GG_ as Biosensor for Oral and Systemic Health Conditions: A Pilot Study
## 3 Results and Discussion
These results imply that SLPO circumstances severely impair the structural integrity and form of cells, necessitating enhanced MreB activity. The variation highlights MreB's essential function in maintaining cell structure under environmental and physiological stress. Cell Shape-Determining Protein (MreB) is a protein found in bacteria that is homologous to actin, a cytoskeletal protein in eukaryotes. MreB plays a crucial role in maintaining cell shape, particularly in rod-shaped bacteria, by organizing the cell wall synthesis machinery [57]. MreB may be upregulated in response to conditions that require enhanced cell wall synthesis or repair, such as exposure to stressors that damage the cell wall or in nutrient-rich conditions. This can help maintain cell shape and integrity under adverse conditions. Currently, little research on bacterial biosensors and proteomics exists. Some studies successfully used proteomics to identify stress response proteins in _Escherichia coli_-based biosensors. In a study, [PERSON] et al. developed a biosensor capable of detecting cellular stress triggered by inefficient protein secretion from the cytoplasm, as well as protein aggregation in the periplasm [58]. The study showed that the biosensor's fluorescence fingerprint could be used to identify induction conditions that stay within the cell's capacity, thereby avoiding stress. These optimized conditions led to improved biomass production and, in some cases, higher yields of soluble recombinant proteins [58]. Similarly, research on _Lactobacillus_ strains has demonstrated their ability to modulate protein expression in response to environmental stressors [57; 58]. According to the results of this work, LGG can serve as a biosensor for changes in metabolism, virulence and stress levels (Figure 4). Probiotic effector molecules derived from LGG have been identified, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes. To the best of our knowledge, no study has been performed in the oral environment. Compared to these studies, the current research on LGG provides novel insights into its potential as an oral biosensor, particularly in detecting bacterial protein expression and pathways that could be related to human oral and systemic health. In a study by [PERSON] et al. [59], it was shown that certain genes and proteins involved in oxidative stress resistance play a key role in the redox balance mechanisms of _Lactobacillus_ species, as they are directly linked to the cellular signaling pathways activated by reactive oxygen species (ROS). Among the commonly identified oxidative stress-related genes and proteins in _Lactobacillus_ spp. are thioredoxin reductase, heme-dependent catalase, thioredoxin, DNA protection protein, and NAD(P)/FAD-dependent oxidoreductase. Particularly, thioredoxin and thioredoxin reductase--along with the genes that encode them--form what is known as the thioredoxin antioxidant system, which plays a central role in protecting the cell from oxidative damage. However, it is worth noting that only a limited number of _Lactobacillus_ species naturally possess these oxidative stress resistance genes and proteins [59]. The future of using LGG as a biosensor lies in its integration into carriers, such as wearable dental aligners, to enable extended and continuous monitoring. This approach would be beneficial in conditions such as diabetes, cardiovascular disease, and inflammatory disorders, where treatment effectiveness varies widely among individuals. Future directions should also prioritize the optimization of LGG as biosensor designs to improve sensitivity and specificity. Increasing the range of proteomic analysis to include diverse populations and environmental conditions will further validate the diagnostic capabilities of LGG. Moreover, longitudinal studies can assess the long-term efficacy and reliability of LGG-based biosensors in clinical settings.