Shintaro Kikuchi*, Toshie Terada*, Chigusa Seki*, Takashi Oshima*, Takuji Sawaya**, Katsutoshi Hokari***, Yasuo Umehara*** and Kazuhiro Takamizawa****

* Department of Applied Microbiology, Muroran Institute of Technology
** Hokkaido Industrial Technology Center
*** Nippon Chemical Feed Co. Ltd.
**** Department of Biotechnology, Faculty of Agriculture, Gifu University

+ Correspondence should be addressed to Shintaro Kikuchi:
(27-1 Mizumoto, Muroran, Hokkaido 050 Japan)

Abstract

Microbial removal of cadmium from a waste tissue (hepatopancreas) of a scallop was examined. During a sequential and mixed cultivation of soil microbes and a strain of sulfate-reducing bacteria in an extract of the tissue, cadmium was removed completely from the extract as the metal-sulfide precipitated. Whereas a significant amount of cadmium remained in the extract after the cultivation of soil microbes or the sulfate-reducing bacterium alone. These results suggested that protein-bound cadmium in the tissue extract would be transformed to a free-state by enzymes like proteases secreted by soil microbes, and then, metal sulfide could be formed with the free-cadmium and hydrogen sulfide produced by the sulfate-reducing bacterium. Availability of the cadmium-free preparation as feed was also discussed.

Key words: a waste tissue of scallop, microbial removal of cadmium, soil microbes, sulfate-reducing bacteria, cadmium sulfide