Sulfides, Disulfides, and Related Compounds

Interest in the possible persistence of aliphatic sulfides has arisen since they are produced in marine anaerobic sediments, and dimethylsulfide may be implicated in climate alteration (Charlson et al. 1987). Dimethylsnlfoniopropionate is produced by marine algae as an osmolyte, and has aronsed attention for several reasons. It can be the source of climatically active dimethylsulfide (Yoch 2002), so the role of specific bacteria has been considered in limiting its flux from the ocean and deflecting the prodncts of its transformation into the microbial sulfur cycle (Howard et al. 2006). 

Sulfides and related componnds may be degraded by a range of different pathways, which are illustrated in the following examples  

Bacteria selected for growth with bis-(3-pentflnorophenylpropy)-sulfide as sulfur source are able to use dimethyl sulfoxide, dibenzyl snlfide, and some long-chain disulfides as sources of sulfur (van Hamme et al. 2004). Degradation takes place by oxidation to the sulfone, scission of the C-S bond to an alkanol, and an alkyl sulfinate that is degraded with loss of the snlfnr, which is nsed for growth. 

The anaerobic redaction of dimethyl snlfide to methane (Oremland et al. 1989), and of dibenzyl disulfide to toluenethiol and finally tolnene (Miller 1992) has been described. Methanomethylovorans hollandica is able to grow anaerobically with both dimethyl sulfide and methanethiol (Lomans et al. 1999) whereas dimethyl sulfide, which is used as an electron donor for the growth of Rhodobacter sulfidophilus, is converted into dimethyl sulfoxide (Hanlon et al. 1994). 

FIGURE 11.9 Elimination reactions during metabolism of aliphatic sulfur compounds (a) cysteine, (b) methionine, and (c) 2-dimethylsulfoniopropionate. 

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