The use of silver-coated ceramic beads for sterilization of Sphingomonas sp in drinking mineral water

It has been established that certain heavy metals including silver have antibacterial properties, and that they may be useful components of antibacterial materials. This knowledge of the antibacterial activity of silver has already been put to use to decrease the occurrence of urinary catheter infections and to develop topical antibacterial agents for burn victims. In this study, the ability of silver-coated ceramic beads (Ag-CBs), sintered at 375, 400, 425, or 450 degrees C, to sterilize Sphingomonas sp. in commercial mineral water was evaluated. Over 3% (w/v) Ag-CBs in mineral water completely sterilized Sphingomonas sp. after 6 h, regardless of the sintering temperature. The Ag-CBs sintered at 400 degrees C were the most useful since they did not produce clouding in the water and the bacteria were effectively killed. The antimicrobial activity of the 400 degrees C-sintered Ag-CBs was comparable to that of free silver ions at 15 mu g/l, showing that the silver ions released from the Ag-CBs resulted in the complete sterilization of the microbial cells in mineral water. These results suggest that Ag-CBs present an easy-to-use option for mineral water sterilization.