SREL Reprint #1816

Biogeochemistry of sulfide oxidizing bacteria in phreatic karst

H.W. Martin1 and R.L. Brigmon2

1Biogeochemical Ecology Division, Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802
2University of Florida, Department of Physiological Sciences, University of Florida, Gainesville, FL 32601

Introduction: Thiothrix sp. is a sulfide oxidizing mixolithotrophic bacteria that has been identified from ecological niches in the aquifer defined by gradient zones where up-welling anoxic sulfide-containing water contacts aerated water. In springs and underwater limestone caves within the Floridan aquifer in Florida, visible colonies of Thiothrix and other bacteria have been observed by divers as thin white mats or tufts on cave floors and as filamentous masses in the water column. Thiothrix sp. usually grows as a mixotroph, obtaining energy from the oxidation of H2S or HS- to elemental S (So) and carbon from a combination of inorganic (HCO3-) and organic C, can use O2 or NO3- as electron acceptors (Larkin and Shinabarger, 1983; Strohl and Schmidt, 1984) and can fix dissolved N2-N (Polman and Larkin, 1990). Thiothrix thrives in a gradient in flowing water in which the sulfide concentration is about 0.1 to 1.0 mg L-1, the O2 concentration is about 10% or less of saturation, pH is near neutrality (7.0 to 7.5), and Ca2+ concentration is high (Bland and Staley, 1978; Lackey et al., 1965; Larkin and Strohl, 1983; Shuttleworth and Unz, 1991; Williams and Unz, 1989).

SREL Reprint #1816

Martin, H.W. and R.L. Brigmon. 1994. Biogeochemistry of sulfide oxidizing bacteria in phreatic karst. pp. 49-51 In: I.D. Sasowsky and M.V. Palmer (Eds.). Breakthroughs in Karst Geomicrobiology and Redox Geochemistry. Karst Waters Institute, Charles Town, WV. 

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).