Adsorption of metal ions to microorganisms and dental plaque.

Abstract

The adsorption of metal ions to 14 species of microorganisms including oral bacteria and samples of dental plaque was investigated. At around neutral pH, which is similar condition as the oral environment, high levels of silver adsorption to cells were demonstrated with Propionibacterium acnes and Fusobacterium nucleatum, while Porphyromonas gingivalis and Actinomyces levoris showed lower levels of silver adsorption. Adsorption of copper ions was observed at higher levels in both P. acnes and Corynebacterium matruchotii. P. gingivalis and A. levoris strains showed only low level adsorption. Samples of dental plaque from 3 different origins were collected from 2 adults respectively or collected and mixed from 124 dental students. These samples showed lower levels of nickel and silver adsorption than P. acnes, and higher levels of metal adsorption than P. gingivalis. The release of the nickel ions, which has been well known as a causative agent for mucous epithelium and skin allergies, from P. acnes cells bound the metal ions by washing was examined. The metal ions were readily released from the bacterial cells by washing with EDTA but not almost by water. This finding indicates that metal ions adsorbed to bacterial cells are not easily released by washing with water. These results suggests that several oral bacteria and dental plaque possess an increased capacity for adsorption of dental metal ions in oral environments. Yamamura, et al.: Metal adsorption to microorganisms and dental plaque 621