DEGRADATION OF MONOSODIUM METHANEARSONIC ACID BY SOIL MICROORGANISMS

Monosodium methanearsonic acid (MSMA) was chosen as the model compound for a study of the degradation of organic arsenicals in soil. Comparison of evolved 14CO2 from four sterile and nonsterile soils 60 days after treatment with MSMA-14C showed that from 1.7 to 10.0% of the MSMA-14C was degraded in nonsterile soil, as compared with 0.7 % in steam-sterilized controls. Four soil microorganisms isolated in pure culture degraded from 3 to 20% of the MSMA-14C to 14CO2 when grown in liquid culture containing 10 p.p.m. of MSMA and 1 gram per liter of yeast extract. Thin-layer chromatography (TLC) on silica gel G-coated plates effected the separation of MSMA, arsenate, and arsenite. Only arsenate and MSMA were detected after TLC of extracts from the soil and microbial growth experiments. These data indicate that soil microorganisms are at least partly responsible for MSMA degradation in soil. © 1968, American Chemical Society. All rights reserved.