Table 1 shows that the adhesion of the three bacteria to SS316 is most excellent at pH 3, decreases when pH increases to 5 and 7 and is least at pH 7. The increase in adhesion at pH 9 is probably due to the ionization of the functional groups (carboxyl and amino groups) on the surface of the bacteria as pH changes.

As the pH rises from 3 to 7, the ionization of the carboxyl groups becomes weaker and more robust. The electrostatic gravitational force between the bacteria and the metal surface gradually increases. Still, at pH 3, the zeta potential of the bacteria approaches 0. The thin double electric layer (EDL) at the solid-liquid interface plays a decisive role. Hence, the bacteria reach the SS316 surface with the lowest adhesion barrier and thus the highest adhesion force. As the pH rises to 9, the concentration of negatively charged COO^- in the liquid environment is more elevated and . It combinestrostatically with the presence of Fe²⁺ on the SS316 surface to produce more excellent adhesion.