Antimicrobial effects of quaternary phosphonium salt intercalated clay minerals on Escherichia coli and Staphylococci aureus

The aim of this research was to determine the antimicrobial properties and influence factors of four clay minerals intercalated by quaternary phosphonium salt (tetradecyl tributyl phosphonium bromide, TDTB) on antimicrobial effects. Escherichia coli (E. coli) and Staphylococci aureus (S. aureus) were chosen for Minimal Inhibitory Concentration (MIC) tests to evaluate the antimicrobial activities of organ-clay minerals. The properties of organ-clay minerals were analyzed by FTIR, XRD, TEM, Z-Average and Zeta potential, and the releasing amount of TDTB into the broth was measured by ICP. The results showed that montmorillonites-TDTB inhibited the growth of E. coli and S. aureus, and the MICs were 200 ± 20 and 80 ± 15 mg/L, respectively. The amount of TDTB released into the broth was 3.42 ± 0.71%. According to the properties of organ-clay mineral, it was indicated that the antimicrobial activities of organ-clay mineral were the synergic effect of the releasing amount of TDTB, Zeta potential, particle size and distribution. The organ-clay mineral with the larger releasing amount of TDTB, the higher Zeta potential, the same particle size with bacterial size and the narrower size distribution exhibited better antimicrobial activity. The present study demonstrated the properties of organ-clay minerals effected their antimicrobial activities, provided theoretically guidance to promote the antimicrobial activity of clay minerals.