Antibacterial properties of metallic elements for alloying evaluated with application of JIS Z 2801 : 2000

Antibacterial properties of 21 metallic elements used as alloying elements (Al, Si, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Ag, Sn, Ta, W, Pb, Au, Pt) was studied. Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus subsp. aureus (Gram-positive bacteria) were used as model bacteria. The film attachment method was adopted for evaluation of antibacterial activity, and Japan industrial standard Z 2801:2000 was applied as the criterion for evaluate antimicrobial abilities of samples. Silver and Cu showed strong bactericidal effects as expected, and following them Co, Ni and Al were moderately toxic. Physiological effects of metals depended on the specie of bacteria. For example, Ni decreased the total viable count of E. coli to 10 cfu/mL in 4 h, while it took 24 h to decrease the total viable count of S. aureus. By judgment following to JIS Z 2801:2000, Pt and Pb were effective only for E. coli, while V and Zr were only for S. aureus. Gold was not toxic even though Au3+ had been reported as strong toxic. Also Mo showed antibacterial effects which can be resulting from decrease in pH of the bacteria suspension.