By using 1,4-dioxane as the sole source of carbon, a 1,4-dioxane-degrading microorganism was isolated from soil. The fungus, termed strain A, was able to utilize 1,4-dioxane and many kinds of cyclic ethers as the sole source of carbon and was identified as Cordyceps sinensis from its 18S rRNA gene sequence. Ethylene glycol was identified as a degradation product of 1,4-dioxane by the use of deuterated 1,4-dioxane-d 8 and gas chromatography-mass spectrometry analysis. A degradation pathway involving ethylene glycol, glycolic acid, and oxalic acid was proposed, followed by incorporation of the glycolic acid and/or oxalic acid via glyoxylic acid into the tricarboxylic acid cycle.

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The high toxicity of diphenylarsinic acid, found in ground water and well water as a probable consequence of the inappropriate disposal of warfare agents, prompted us to study the reaction, monitored by 1H and 13C NMR spectroscopy, of the compound and its monophenyl analogue, phenylarsonic acid, with cellular thiols as represented, in particular, by glutathione. Glutathione reduced the phenylarsenic acids to trivalent forms and complexed them: diphenylarsinic acid to a monoglutathione adduct and phenylarsonic acid to a diglutathione adduct. The complexes were characterized by 1H and 13C NMR spectroscopy and mass spectrometry. The NMR spectra showed the diastereotopic nature of the two phenyl groups in the diphenylarsinic acid-glutathione compound, and of the two glutathione residues in the phenylarsonic acid-diglutathione complex. The stereochemistry of thiol compounds of phenylarsonic acid was further explored by 1H and 13C NMR spectroscopy of the L-cysteine complex. The diphenylarsinic acid-glutathione complex was stable below pH 12 but at higher pH the complex dissociated into diphenylarsinous acid and reduced glutathione. The released diphenylarsinous acid then oxidized to diphenylarsinic acid with a half-life of about 7 h at pH 13 and at room temperature.

Microorganisms were not directly accumulated when soil contaminated to about 0.5 mM with diphenylarsinic acid (DPAA) was used as the sole source of carbon. However, using toluene as the carbon source yielded several isolates, which were then used in cultivation with DPAA as the sole source of carbon. By these methods, Kytococcus sedentarius strain NK0508, which can grow in up to 0.038 mM DPAA, was isolated. The toxicity of DPAA retarded the growth of K. sedentarius and the direct accumulation of DPAA-utilizing microorganisms from environmental samples. This strain can utilize about 80% of DPAA and phenylarsonic acid as the sole source of carbon for 3 days. Degradation products of DPAA were determined to be cis, cis, muconate and arsenic acid. When K. sedentarius was cultivated with methylphenylarsinic acid and diphenylmethylarsine, about 90% and 10% degradation of the two compounds, respectively, were observed. Diphenylmethylarsine oxide, possibly synthesized by methylation of DPAA, was detected as one of the transformation products. These results suggest that degradation is initiated by splitting of the phenyl groups from the arylarsenic compounds with subsequent hydroxylation of the phenyl groups and ring opening to yield cis, cis, muconate.

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