Production of Volatile Derivatives of Metal(loid)s by Microflora Involved in Anaerobic Digestion of Sewage Sludge

Abstract

Gases released from anaerobic wastewater treatment facilities contain considerable amounts of volatile methyl and hydride derivatives of metals and metalloids, such as arsine (AsH 3 ), monomethylarsine, dimethylarsine, trimethylarsine, trimethylbismuth (TMBi), elemental mercury (Hg 0 ), trimethylstibine, dimethyltellurium, and tetramethyltin. Most of these compounds could be shown to be produced by pure cultures of microorganisms which are representatives of the anaerobic sewage sludge microflora, i.e., methanogenic archaea (Methanobacterium formicicum, Methanosarcina barkeri, Methanobacterium thermoautotrophicum), sulfate-reducing bacteria (Desulfovibrio vulgaris, D. gigas), and a peptolytic bacterium (Clostridium collagenovorans). Additionally, dimethylselenium and dimethyldiselenium could be detected in the headspace of most of the pure cultures. This is the first report of the production of TMBi, stibine, monomethylstibine, and dimethylstibine by a pure culture of M. formicicum.Volatile methyl and hydride derivatives of metal(loid)s are found in gases released from natural environments such as sediments, wetlands (40), and hydrothermal springs (26), as well as from anthropogenic environments such as wastewater treatment plants and waste deposits (18). Some of the compounds are of anthropogenic origin, for example, alkylated tin and lead derivatives, whereas others are produced in environmental settings either due to chemical transalkylation or due to biologically mediated methylation and hydride formation (the addition of a formal hydride ion mediated by an organism) (11,36). The production of volatile metal(loid) compounds is a significant part of the biogeochemical cycles of metals (e.g., Bi, Hg, and Sn) and metalloids (e.g., As, Sb, Se, and Te) because of the increased mobility of the resultant compounds. Additionally, most of the volatile derivatives exhibit higher toxicity than their inorganic counterparts, since organic derivatives are lipophilic and are thus more biologically active (35,36). Exceptions are arsenic and selenium, in which cases the inorganic, nonmethylated forms are more toxic than the methylated derivatives (14).Following the pioneering work of Gosio (23) and Challenger et al. (6, 7), the mechanism for the biomethylation of arsenic has been studied extensively with various fungi (10, 15), bacteria (3), archaea (3, 30), and mammals (1, 38, 41), including humans (13). As proposed by Challenger, the biomethylation of selenium and tellurium follows the same mechanism as arsenic but, in general, studies investigating these processes are rather rare (16,22,38). Mercury biomethylation, on the other hand, has been studied in more detail because of poisonings by methylmercury compounds (4,8,29,33). Although stibine has been implicated as a cause in sudden infant death syndrome (31), up to now, only trimethylantimony was detected as a biovolatilization product of antimony in the headspace of soil samples (24) and of pure cultures of Scopulariopsis brevicaulis (12,27). The biomethylation of inorg...

A review on completing arsenic biogeochemical cycle: Microbial volatilization of arsines in environment

“…In anaerobic human gut, marine mud, drilling swamp mud and sewage sludge, where methane is produced as well as volatile metals and metalloids, there is large number of anaerobic methanoarchaea capable of volatilizing As (Bachofen et al, 1995;Michalke et al, 2000). Biomethylation and bio-volatilization of metals and metalloids, As in particular, is very similar to methane biosynthesis and is possibly an inherent feature of methanoarchaea (McBride and Wolfe, 1971;Meyer et al, 2008;Mestrot et al, 2013).…”

“…Pseudomonas and Alcaligenes also produced AsH 3 from both As(III) and As(V) under anaerobic conditions (Cheng and Focht, 1979). According to Wickenheiser's research, TMAs is the only volatile As species formed by sulfatereducing bacteria and the peptolytic bacteria Clostridium collagenovorans, Desulfovibrio gigas and D. vulgaris (Wickenheiser et al, 1998;Michalke et al, 2000). Though TMAs is prone to be oxidized to nonvolatile TMAsO in water environment, TMAsO can be reduced de novo under aerobic or anaerobic conditions by several bacteria.…”

Identification and Characterization of Arsenite Methyltransferase from an Archaeon,Methanosarcina acetivoransC2A

“…1,18 For example, arsenic volatilization has been observed in many paddy soils or wetlands. 19−23 Methylation and volatilization of metal(loid)s have been regarded as an inherent feature of methanoarchaea, 24,25 though the enzymatic mechanism of As methylation by archaea remains unknown.…”

Mercury Inactivates Transcription and the Generalized Transcription Factor TFB in the Archaeon Sulfolobus solfataricus

“…Methanogenic archaea, however, are known to produce volatile methyl and hydride derivatives of metals and metalloids (30). Sulfolobus solfataricus is a hyperthermophile and a member of the Crenarchaeota, one of two major subdivisions of cultivated archaea.…”