Identification of extracellular arsenical metabolites in the growth medium of the microorganisms apiotrichum humicola and scopulariopsis brevicaulis

Abstract

The separation and identification of some of the arsenic species produced in cells present in the growth medium when the microorganisms Apiotrichum humicola (previously known as Candida humicola) and Scopulariopsis brevicaulis were grown in the presence of arsenicals were achieved by using hydride generation-gas chromatography-atomic absorption spectrometry methodology (HG GC AA). Arsenite, monomethylarsonate, dimethylarsinate and trimethylarsine oxide were detected following incubation with arsenate. With arsenite as a substrate, the metabolites were monomethylarsonate, dimethylarsinate and trimethylarsine oxide; monomethylarsonate afforded dimethylarsinate and trimethylarsine oxide, and dimethylarsinate afforded trimethylarsine oxide. Trimethylarsine was not detected when the arsenic concentration was 1 ppm.

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

“…An extended model (Fig. 5) for arsenic methylation involving both cells and medium was proposed (67). The observed reaction rates suggested a possible sequential transfer of 2 methyl groups from SAM to methylarsonate as indicated.…”

“…Preconditioning of cells with dimethylarsinate improves trimethylarsine formation from arsenate and dimethylarsinate. In later experiments, the nonvolatile components of C. humiculus and S. brevicaulis were identified (67). These experiments used low levels (1 ppm) of the arsenic substrates, and under these conditions there was no detectable formation of trimethylarsine with either organism.…”

Biomethylation of Arsenic in an Arsenic-rich Freshwater Environment

“…The determination of inorganic and methylated arsenic in biological samples was accomplished using the hydride generation coupled with atomic absorption spectrometry 23,34 or mass spectrometry. 24,31,35 In previous work concerning the biomethylation of arsenic, Cullen et al measured arsine or methylated arsines using an HG-GC-MS system operating in the wide-scan mode to investigate the biomethylation of arsenic by marine algae.…”

Arsenic speciation by hydride generation-Quartz furnace atomic absorption spectrometry. Optimization of analytical parameters and application to environmental samples

“…Biological reactions occurring in terrestrial [9,10] and marine organisms [11][12][13][14] convert inorganic arsenate (AsV) and arsenite (AsIII) to monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA) and trimethylarsine oxyde (TMAO). Moreover, microorganisms are able to reduce arsenate in arsenite previously released into solution prior to methylation [15,16].In order to understand these biochemical processes and since arsenic toxicity depends on its speciation [17], several techniques have been developed to determine the concentrations of the different arsenic compounds [18][19][20][21][22]. Methods based on HPLC separation are more and more often used in arsenic speciation and a review of the main techniques using this separation has been recently published by Guerin et al [23].…”

“…Biological reactions occurring in terrestrial [9,10] and marine organisms [11][12][13][14] convert inorganic arsenate (AsV) and arsenite (AsIII) to monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA) and trimethylarsine oxyde (TMAO). Moreover, microorganisms are able to reduce arsenate in arsenite previously released into solution prior to methylation [15,16].…”