Dear Sir. Concerning your issue about the effects of lower pH value on the bacterial growth . The optimum growth pH is the most favorable pH for the growth of an organism. The lowest pH value that an organism can tolerate is called the minimum growth pH and the highest pH is the maximum growth pH. These values can cover a wide range, which is important for the preservation of food and to microorganisms’ survival in the stomach. For example, the optimum growth pH of Salmonella spp. is 7.0–7.5, but the minimum growth pH is closer to 4.2. I think the following below links may help you in your analysis:

https://cnx.org/contents/NxduIcMv@3/The-Effects-of-pH-on-Microbial-Growth

https://aem.asm.org/content/aem/39/3/604.full.pdf

https://www.physics.uoguelph.ca/psi/papers/Bacteria%20&%20Biofilms/Bacteria_Adhesion/Tan_BiotechBioeng98.pdf

Thanks