GROWTH KINETICS OF STREPTOCOCCUS SALIVARIUS IN VARIOUS CULTURE MEDIA AND EVALUATION OF ITS PROBIOTIC POTENTIAL FOR DENTISTRY

Subject. The oral cavity represents a complex microbial ecosystem in which the balance between commensal and pathogenic microorganisms plays a key role in maintaining oral health. Probiotic bacteria capable of producing bacteriocins are considered promising agents for the prevention of oral infectious diseases. Among them, Streptococcus salivarius is a commensal microorganism of the oral cavity capable of producing antimicrobial peptides that inhibit the growth of pathogenic bacteria. Objective: To evaluate the growth kinetics of Streptococcus salivarius in different nutrient media and to determine the optimal conditions for biomass accumulation and viability of bacterial cells for potential probiotic applications in dentistry. Materials and Methods. The strain Streptococcus salivarius was cultivated in four nutrient media: meat-peptone broth, sugar broth, medium 199 and MRS medium. Growth kinetics were evaluated by measuring optical density at 600 nm every hour for 24 hours using a PowerWave X spectrophotometer. The duration of the lag phase, growth rate and maximal concentration of viable cells were analyzed. Statistical analysis was performed using StatTech v.4.8.7. Results and Discussion. Significant differences in the duration of the lag phase were observed depending on the composition of the culture medium. The longest adaptation period was recorded in MRS medium (16 hours), which exceeded that in other media by approximately eight times (p = 0.001). The transition from the exponential to stationary phase in meat-peptone broth occurred significantly faster (10±2.7 h) than in MRS medium (20 ±1 h; p = 0.01). The highest concentration of viable cells was detected in meat-peptone broth (881.1 ±419.2 arbitrary units; p = 0.006 compared with MRS). Medium 199 and sugar broth also demonstrated significantly higher viable cell counts compared with MRS medium (699.4 ±61.9 and 713.5 ±134.9 arbitrary units respectively). Conclusion. The composition of nutrient media significantly affects the growth kinetics and viability of Streptococcus salivarius. Media containing readily available nutrient substrates provide faster adaptation and higher biomass yield. These findings may be useful for optimizing the cultivation of probiotic strains producing bacteriocins for the prevention of oral infectious diseases and modulation of the oral microbiome in dentistry.