3.3.2 pH value
In a liquid environment, changes in pH affect the surface charge properties of bacteria through the isoelectric point theory[112]. When the pH in the fluid domain is greater than the bacterial isoelectric point, the ionization of the carboxyl groups of amino acids on the bacterial surface makes them negatively charged; when the pH in the liquid environment is less than the bacterial isoelectric point, the ionization of the amino groups of amino acids on the bacterial surface makes them positively charged.
Sheng et al. [113] measured the adhesion of three bacteria (Pseudomonas sp, D. desulfuricans, and D. Singaporeans, with isoelectric points of 2.1, 3.5, and 2.7, respectively) to 316 stainless steel (SS316) in different pH artificial seawater (ASW) environments, as shown in Table 1.