Sulphate reduction pathway

Jorgensen B. B. and Bak F. (1991) Pathways and microbiology of thiosulphate transformations and sulphate reduction in a marine sediment (Kattegat, Denmark). Appl. Environ. Microbiol 57(3), 847-856. 

The nucleotides are then used in the synthesis of the sulphur amino acids. The pathway is still uncertain, but it is thought that PAPS is reduced to sulphide via sulphite. The amino acid serine is then combined with sulphide to produce cysteine. Thiosulphate is readily used by microbes in place of sulphate and is thought to be on the direct reduction pathway. The overall reaction may be represented as follows ... 

FIGURE 4. Pathway of dissimilatory sulphate reduction in Desulfovibrio. (adapted from Roy Trudinger 73). ... 

Anions from the Schiffs base (78) can be C- or A -alkylated with ethyl iodide or diethyl sulphate. The ratio of the products depends both on the solvent and on the presence of 18-crown-6. In non-polar solvents, the crown ether increases the solubility of the base, and C-alkylation is the major pathway. In dipolar aprotic solvents, the 18-crown-6 breaks up ion pairs by solvation of the Na" cation, and favours A -alkylation. A nerylsulphonamide, formed from (79), undergoes regiospecific reductive desulphonylation to give nerol (80), which implies that (79) is an effective synthon for cisoid iso-prenoids. Chiral complexes of crown ethers, e.g. (81), catalyse the Michael addition reaction of j3-keto-esters and methyl vinyl ketone to give adducts in high optical yields. ... 

As shown in Figure 6, CT is susceptible to transformation by parallel, competing pathways. Transformation of CT to CO, occurs in mixed cultures under methanogenic, denitrifying, and sulphate-reducing conditions, but typically, CF is also produced by a parallel pathway [3, 26,30,69,80]. Desulfobacterium autotrophicum [37] and Clostridium sp. [71] reductively dehalogenated CT to trichloromethane and... 

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