Preprint / Version 1

The Effect of pH upon the Growth of Streptococcus salivarius


  • Rohit Kottomtharayil High Technology High School



Streptococcus salivarius, pH, oral, oral microbiome


S. mutans is a detriment to the oral microbiome leading to tooth decay and cavities. However, S. salivarius can produce alkaline to restrict the growth of S. mutans. Thus, to optimize the growth of S. salivarius, the present study analyzes the favorable pH level standards for reproduction of S. salivarius. It was hypothesized that environments with alkaline pH levels will disrupt a Streptococcus salivarius cells’ activity and hydrogen bonding. The hypothesis was not supported by the results. The independent variables were the pH levels and time, and the dependent variable was the growth of S. salivarius. Bacteria colonies grew in agar plate environments of pH 5, 6, 7, 8 and 10. Environments with pH 5, pH 6, and pH 10 were incapable of fostering bacteria colonies, while pH7 and pH8 colonies could.


Abranches, J., et al. “Biology of Oral Streptococci.” Microbiology Spectrum, vol. 6, no. 5, 5 Oct. 2018,, 10.1128/microbiolspec.gpp3-0042-2018.

Arweiler, Nicole B., and Lutz Netuschil. “The Oral Microbiota.” Springer Link, Springer International Publishing, 2016,

Deo, Priya Nimish, and Revati Deshmukh. “Oral Microbiome: Unveiling the Fundamentals.” Journal of Oral and Maxillofacial Pathology : JOMFP, vol. 23, no. 1, 2019, pp. 122–128,, 10.4103/jomfp.JOMFP_304_18.

Garcia, S.S., et al. “Targeting Of Streptococcus Mutans Biofilms by a Novel Small Molecule Prevents Dental Caries and Preserves the Oral Microbiome.” Journal of Dental Research, vol. 96, no. 7, 10 Mar. 2017, pp. 807–814, 10.1177/0022034517698096. Accessed 1 Dec. 2020.

Gerdt, Joseph P., et al. “Unraveling the Contributions of Hydrogen-Bonding Interactions to the Activity of Native and Non-Native Ligands in the Quorum-Sensing Receptor LasR.” Organic & Biomolecular Chemistry, vol. 13, no. 5, 2015, pp. 1453–1462,, 10.1039/c4ob02252a. Accessed 10 Jan. 2023.

Hassel, Tammy. “EJPPS | Article| Agar Desiccation – the Causes and How to Address Them.” EJPPS,


Jin, Qusheng, and Matthew F. Kirk. “PH as a Primary Control in Environmental Microbiology: 1. Thermodynamic Perspective.” Frontiers in Environmental Science, vol. 6, 1 May 2018, 10.3389/fenvs.2018.00021.

Olson, Eric R. “Influence of PH on Bacterial Gene Expression.” Molecular Microbiology, vol. 8, no. 1, Apr. 1993, pp. 5–14, 10.1111/j.1365-2958.1993.tb01198.x.

Poorni, Saravanan, et al. “Probiotic Streptococcus Strains in Caries Prevention: A Systematic Review.” Journal of Conservative Dentistry, vol. 22, no. 2, 2019, p. 123, 10.4103/jcd.jcd_505_18. Accessed 5 Sept. 2021.

Ratzke, Christoph, and Jeff Gore. “Modifying and Reacting to the Environmental PH Can Drive Bacterial Interactions.” PLOS Biology, vol. 16, no. 3, 14 Mar. 2018, p. e2004248,, 10.1371/journal.pbio.2004248.

Stašková, Andrea, et al. “Antimicrobial and Antibiofilm Activity of the Probiotic Strain Streptococcus Salivarius K12 against Oral Potential Pathogens.” Antibiotics, vol. 10, no. 7, 29 June 2021, p. 793, 10.3390/antibiotics10070793. Accessed 2 Dec. 2021.

Tristram, H., et al. “Review of Biochemistry of Bacterial Growth.” Science Progress (1933- ), vol. 57, no. 225, 1969, pp. 122–125, Accessed 11 Jan. 2023.