ECOPHYSIOLOGICAL EVIDENCE THAT ACHROMATIUM-OXALIFERUM IS RESPONSIBLE FOR THE OXIDATION OF REDUCED SULFUR SPECIES TO SULFATE IN A FRESH-WATER SEDIMENT

Citation
Nd. Gray et al., ECOPHYSIOLOGICAL EVIDENCE THAT ACHROMATIUM-OXALIFERUM IS RESPONSIBLE FOR THE OXIDATION OF REDUCED SULFUR SPECIES TO SULFATE IN A FRESH-WATER SEDIMENT, Applied and environmental microbiology, 63(5), 1997, pp. 1905-1910
Citations number
45
Categorie Soggetti
Microbiology,"Biothechnology & Applied Migrobiology
ISSN journal
00992240
Volume
63
Issue
5
Year of publication
1997
Pages
1905 - 1910
Database
ISI
SICI code
0099-2240(1997)63:5<1905:EETAIR>2.0.ZU;2-4
Abstract
Achromatium oxaliferum is a large, morphologically conspicuous, sedime nt-dwelling bacterium, The organism has yet to be cultured in the labo ratory, and very little is known about its physiology, The presence of intracellular inclusions of calcite and sulfur have given rise to spe culation that the bacterium is involved in the carbon and sulfur cycle s in the sediments where it is found, Depth profiles of oxygen concent ration and A, oxaliferum cell numbers in a freshwater sediment reveale d that the A, oxaliferum population spanned the oxic-anoxic boundary i n the top 3 to 4 cm of sediments, Some of the A, oxaliferum cells resi ded at depths where no oxygen was detectable, suggesting that these ce lls may be capable of anaerobic metabolism, The distributions of solid -phase and dissolved inorganic sulfur species in the sediment revealed that A. oxaliferum was most abundant where sulfur cycling was most in tense, The sediment was characterized by low concentrations of free su lfide, However, a comparison of sulfate reduction rates in sediment co res incubated with either oxic or anoxic overlying water indicated tha t the oxidative and reductive components of the sulfur cycle were tigh tly coupled in the A, oxaliferum-bearing sediment, A positive correlat ion between pore mater sulfate concentration and A, oxaliferum numbers was observed in field data collected over an 18-month period, suggest ing a possible link between A, oxaliferum numbers and the oxidation of reduced sulfur species to sulfate, The field data were supported by l aboratory incubation experiments in which sodium molybdate-treated sed iment cores were augmented with highly purified suspensions of A, oxal iferum cells, Under oxic conditions, rates of sulfate production in th e presence of sodium molybdate were found to correlate strongly,vith t he number of cells added to sediment cores, providing further evidence for a role for A, oxaliferum in the oxidation of reduced sulfur.