The sulfur cycle in a permanently meromictic haloalkaline lake

Abstract

Soap Lake is a haloalkaline lake located in central Washington. This lake is a remnant of the Missoula flood events that created the landscape of western Montana, the southeastern portion of Washington state, and much of Oregon. It is 15,000 -20,000 years old, and has maintained a stable meromixis for the last 10,000 years. This carbonate lake is characterized by a brackish mixolimnion, and a monimolimnion with a salinity of ~14%. The pH of both layers of the lake is approximately 10. Both layers also have a high concentration of dissolved sulfate, with the mineral mirabilite (Na 2 SO 4 ·10H 2 O) found in the monimolimnion sediments. Sulfide concentrations in the monimolimnion exceed 100 mM. As part of the mission of the NSF Soap Lake Microbial Observatory, microorganisms involved in the sulfur cycle in this lake were studied in terms of their diversity and function. High rates of sulfate reduction were measured in both layers of the lake, with new species of sulfate-reducing bacteria seen in both areas. A particularly novel psychrophilic sulfur oxidizer was isolated from the monimolimnion. This organism has the ability to induce the formation of mirabilite, which was assumed to be an abiotically deposited evaporite mineral. This is the first evidence for a biogenic origin of this mineral. This leads to the possibility that related sulfate minerals, such as those reported on the Mars surface, may have a biogenic origin.

A Streamlined Strategy for Biohydrogen Production with Halanaerobium hydrogeniformans, an Alkaliphilic Bacterium

“…Soap Lake, Washington, a highly haloalkaline lake, possesses a pH value of 10, 15–140 g/L NaCl, and anaerobic lake bottom sediments with extraordinarily high sulfide concentrations (Anderson, 1958; Mormile et al, 1999; Pinkart et al, 2006; Sorokin et al, 2007; Dimitriu et al, 2008) making it an ideal location to obtain haloalkaliphilic bacteria.…”

“…There is a wide diversity of alkaliphilic bacteria spanning several phylogenic groups, most notably from soda lakes (Duckworth et al, 1996 ; Jones et al, 1998 ; Rees et al, 2004 ); however, their application for H 2 production has not been investigated. Soap Lake, Washington, a highly haloalkaline lake, possesses a pH value of 10, 15–140 g/L NaCl, and anaerobic lake bottom sediments with extraordinarily high sulfide concentrations (Anderson, 1958 ; Mormile et al, 1999 ; Pinkart et al, 2006 ; Sorokin et al, 2007 ; Dimitriu et al, 2008 ) making it an ideal location to obtain haloalkaliphilic bacteria.…”