Screening of organomercurial-volatilizing bacteria in the mercury-polluted sediments and seawater of Minamata Bay in Japan

Abstract.

The special organomercurial-volatilizing bacteria found in the seawater and sediments of Minamata Bay were screened to develop a method for the removal of mercury to produce clean products. A total of 104 mercury-resistant bacteria that could grow on an agar plate containing 40 µg/ml of HgCl₂ were isolated from Minamata Bay. Almost all strains were Gram-negative rods. Eight of the 104 strains volatilized only mercuric chloride, while 21 of the 104 strains volatilized all of the organomercurials used in this study. Four strains isolated from the seawater were most resistant to methyl mercuric chloride, ethyl mercuric chloride, thimerosal, and fluorescein mercuric acetate as well as HgCl₂, and volatilized all of the organomercurials used in this study. We were able to screen the most mercury-resistant bacteria and organomercurial-volatilizing bacteria, which contained an organomercurial lyase with a particularly wide range of substrate specificity.