Small amounts of methylmercury were produced during 7 days aerobic growth in the presence of sublethal amounts of mercuric chloride by the following bacterial species studied:Pseudomonas fluorescens, Mycobacterium phlei, Escherichia coli, Aerobacter aerogenes, Bacillus megaterium.
Under the same conditions methylmercury was also formed by mycelium of the fungi investigated:Aspergillus niger, Scopulariopsis brevicaulis andSaccharomyces cerevisiae.
The concentration of the methylmercury produced by the various organisms did not vary much and was of the same order of magnitude as that found in Swedish experiments with lake sediments.
In bacteria most of the methylmercury formed was present in the culture liquid, whereas the remainder was in or on the cells. In contrast, methylmercury formed by fungi was for the greater part present in the mycelium.
The production of methylmercury byE. coli andA. aerogenes was lower under anaerobic conditions than under aerobic conditions.