Bio-mineralization of heavy elements on microbial cell surface

Onuki, Toshihiko; Tanaka, Kazuya  ; Jiang, M.; Kozai, Naofumi   ; Sakamoto, Fuminori  ; Suzuki, Yoshinori*; Utsunomiya, Satoshi*

The interaction of heavy elements involving actinides with microorganisms has been studied by experiments. Here, we report the nanoscale mineralization process of REE phosphate on microbial cell surfaces and sorption of REE by biogenic Mn oxide. We found that dissolved Ce was accumulated on the cell surface, and precipitated as nanoscale phosphate mineral, even though no P was added in the solution. The analyses of nanoscale phosphate mineral indicate that the sorbed Ce on the cell surfaces reacted with P released from inside the yeast cell, resulting in the formation of Ce(III) phosphate nanocrystallites of monazite. The biogenic Mn oxide (plus microbial cells) showed large a positive Ce anomaly in acid solution. With increasing pH, the positive Ce anomaly became less pronounced. Furthermore, negative Ce anomalies were observed at a pH of more than 6.5. This anomaly change was caused by organic matters released by bacteria.