Effect of Nitrate Injection on SRB Physiology

By definition, SRB reduce sulfate, although there are some strains that also reduce nitrate, e.g., Desulfovibrio desulfuricans strain ATCC 27774 (Gonzalez et al. 2006). Peculiarly, such strains may not downregulate genes for enzymes involved in sulfate reduction when they are reducing nitrate hence the use of alternative electron acceptors by SRB serves a very different purpose than, for instance, in Escherichia coli, where distinct gene-expression patterns are established for cells grown with...

Dissimilation of Organosulfonates

Desulofnation Reaction

We have seen that the sulfonates are costly to generate. Either a cell invests a high-energy bond to obtain a sulfonate, or it risks oxidative stress by involving an oxygenase. The carbon-sulfonate bond is a strong bond, about as strong as a carbon-carbon bond, and the first organic chemists were astonished at the resistance of taurine to strong acid or alkali. The consequence for the biodegradation of orga-nosufonates is that a very stable bond must be broken. We believe that the natural...

Conclusions and Outlook

Research conducted at deep-sea hydrothermal vents over the last decade has revealed that sulfur oxidation is mediated by a diverse group of organisms. Traditionally, Gammaproteobacteria, either free-living or in a symbiotic association, were seen as the main sulfur-oxidizers at these systems. Only recently have we begun to appreciate the importance of Epsilonproteobacteria for autotrophic carbon production in general and in particular for sulfur oxidation (Campbell et al. 2006). It might well...

Biosynthesis of Organosulfonates

Sulfopyruvate

A major part of our understanding of the biosynthesis of non-carbohydrate, aliphatic sulfonates comes from White (1984, 1986), who set out to characterize the biosynthesis of coenzyme M in methanogenic archaea, and of a sulfolipid in bacteria (capnine Fig. 14.1). The two turned out to be related (Fig. 14.3), and the later discovery that coenzyme M is involved in the cleavage of epoxides in aerobic bacteria involved in alkene degradation (Coleman and Spain 2003) broadens the relevance of White's...

Fsr a Sulfite Detoxification Tool and an Assimilatory Enzyme

In cells receiving sulfite, Fsr and methylcoenzyme M reductase subunits are expressed at comparable levels (Fig. 16.3b) the latter is a catabolic enzyme and represents up to 30 of the cellular protein in a methanogen (Rouviere and Wolfe 1987 Thomas et al. 1987). From the data presented in Sect. 16.7, it can be calculated that the extracts of Methanocaldococcus jannaschii grown with sulfite reduce this oxyanion with H2F420 at a rate of 2.7-3.7 imol min-1 mg-1 protein. With reduced...