A total of 207 bacterial cultures, isolated from environmental samples, was screened for ability to degrade methylmercury. Of these, 30 were found positive for aerobic demethylation. Twenty-two of these were shown to be facultative anaerobes and 21 of these degraded methylmercury anaerobically. All positive species volatilized methylmercury aerobically, and methane was produced as a degradation product. Although methylmercury degradation was complete in most cases, material balances indicated some of the inorganic mercury formed was not volatilized and is presumed bound to the cells. All positive isolates were tolerant to at least 0.5 ,ug of methylmercury per ml, and the extent of volatilization of mercury increased with concentration to the threshold value. The results indicate that demethylating species are prevalent in the environment and may be important in suppressing the methylmercury content of sediments.
A total of 207 bacterial cultures, isolated from environmental samples, was screened for ability to degrade methylmercury. Of these, 30 were found positive for aerobic demethylation. Twenty-two of these were shown to be facultative anaerobes and 21 of these degraded methylmercury anaerobically. All positive species volatilized methylmercury aerobically, and methane was produced as a degradation product. Although methylmercury degradation was complete in most cases, material balances indicated some of the inorganic mercury formed was not volatilized and is presumed bound to the cells. All positive isolates were tolerant to at least 0.5 μg of methylmercury per ml, and the extent of volatilization of mercury increased with concentration to the threshold value. The results indicate that demethylating species are prevalent in the environment and may be important in suppressing the methylmercury content of sediments.
The formation of D-homoannulated isomers during the 16a-hydroxylation of 9a-fluorohydrocortisone and other steroids by Streptomyces roseochromogenes was found to be nonbiological and to be induced by excessive iron in the medium. This iron-induced isomerization could be prevented by the addition of phosphate to the medium. Similar isomerizations during the 1,2dehydrogenation of 9a-fluoro-16a-hydroxyhydrocortisone by Bacterium cyclo-oxydans could also be prevented by the addition of phosphate. Productioni of 3-keto_-A 4-pregnadienes by Bacteriuhm cyclo-oxydans. U. S. Patent 2,822,318. M1OYER, A. J. 1953 Effect of alcohols on t;he mycological production of citric acid in surface and submerged culture. I. Nature of the alcohol effect. Appl. Microbiol.,
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