Environmental Engineering Reference
In-Depth Information
Chemolithotrophic microorganisms, primarily SRB, shuttle electrons to sulfoxy
compounds or S
0
with the accumulation of H
2
S where sulfur is in the most reduced
form. Aerobic SOB and CSB facilitate the removal of reduced sulfur compounds with
the production of sulfate. Although there has been considerable advancement to
understand the enzymology of enzymes for production and utilization of H
2
S, further
studies are needed to establish gene activities for these sulfur-metabolizing enzymes.
Such genomic studies should provide an insight into ancestry for horizontal gene
transfer and to understand the energetic processes that drive the inorganic sulfur
reactions. Since considerable similarity exists in the enzymology of H
2
S production
and H
2
S utilization, future studies will be needed to determine which process
evolved first.
Furthermore, investigations of the evolutionary links between the biological
cycles of sulfur and nitrogen will be important to pursue since [4Fe-4S] clusters,
iron porphyrins, and MGD cofactors are used in enzymes for both sulfite to
hydrogen sulfide and nitrite to ammonia reduction [
20
].
Abbreviations and Definitions
A. Acidianus
acetyl-CoA acetyl-coenzyme A
ADP adenosine 5'-diphosphate
Alc. Allochromatium
AMP adenosine 5'-monophosphate
APS adenosine 5'-phosphosulfate
APSR adenylylsulfate reductase
Ar. Archaeoglobus
aSiR assimilatory-type sulfite reductase
asr anaerobic sulfite reduction
ATP adenosine 5'-triphosphate
ATPS ATP sulfurylase
CSB colorless sulfur bacteria
D. Desulfovibrio
Dba. Desulfobacter
Dbu. Desulfobulbus
DMSO dimethylsulfoxide
Drm. Desulfuromonas
Dsm. Desulfomicrobium
dSiR dissimilatory sulfite reductase
Dst. Desulfotomaculum
D. vulgaris
H
Desulfovibrio vulgaris
Hildenborough
ʔ
G
0'
standard free energy change
E.
Escherichia
E
0'
standard reduction potential
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