Methods in Enzymology Vol.243 Inorganic Microbial Sulfur Metabolism

This chapter describes sulfate transport in microorganisms. It discusses uptake experiments with whole cells of dissimilatory sulfate-reducing bacteria (SRB). The performance of an assimilatory sulfate uptake system requires effective uptake of sulfate to secure biosynthesis. High affinity is more advantageous than high rates of uptake or a low energy requirement for the process. Sulfate-transport systems must allow uptake at high rates. High affinity is required, especially in fresh-water environments, which typically reveal low sulfate concentrations. L-methionine, thiosulfate, and in some species cysteine, are used as sulfur sources to repress assimilatory sulfate transport systems. With dissimilatory SRB the highest accumulation factors are obtained after continuous growth in chemostats under sulfate limitation. Assimilatory sulfate transport is easier to follow than dissimilatory sulfate transport, as the uptake rates are lower, primary transport systems (if involved) are unidirectional, and the label is fixed in the cells. Dissimilatory sulfate reduction results in the formation of volatile H2S, which is immediately set free. Therefore, for transport studies dissimilatory sulfate reduction must be inhibited, if possible, without interfering with the driving forces for sulfate accumulation.

• Series: Methods in Enzymology (Book 243)
• Hardcover: 682 pages
• Publisher: Academic Press;
• Language: English
• ISBN-10: 0121821447
• ISBN-13: 978-0121821449
• Product Dimensions: 6 x 1.5 x 9 inches

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