Sulfate reductase assays

Enzyme activity Hydrogenase assay or sulfate reductase assay Measures enzyme activity in a field sample as a rate of reaction. Commercial kits are available. Hydrogenase activity may be related to MIC, while sulfate reductase assesses the presence of SRB. 

Enzyme-Based Assays An increasingly popular approach is the use of commercial kits to assay the presence of enzymes associated with microorganisms suspected to cause problems. For example, kits are available for the sulfate reductase enzyme common to SRBs [23]. This technique takes advantage of the fact that SRBs reduce sulfate to sulfide through the APS-reductase enzyme, common to all SRBs. Measurement of the amount of APS-reductase in a sample gives an estimate of SRBs present. The test does not require bacterial growth and the entire test takes only 15 to 20 minutes [19]. 

The MT T assay is another colorimetric method to assess cell viability. NAD(P)H (nicotinamide adenine dinucleotide(P)H)-dependent cellular oxidoreductase enzymes may, under defined conditions, reflect the number of viable cells present. These enzymes are capable of reducing the tetrazolium dye MTT 3-(4,5-diwiethylfhiazol-2-yl)-2,5-diphenylletrazolium bromide to its insoluble purple-coloured formazan (Figure 7.71). In living cells, the originally yellow MTT is converted by cellular reductase to purple formazan (Mosmann, 1983). A solubilisation solution (usually either dimethyl sulfoxide or sodium dodecyl sulfate dissolved in diluted hydrochloric acid) is added to dissolve the insoluble... 

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