Abstract
Soap Lake is a meromictic, alkaline (∼pH 9.8) and saline (∼14–140 g liter-1) lake located in the semiarid area of eastern Washington State. Of note is the length of time it has been meromictic (at least 2000 years) and the extremely high sulfide level (∼140 mM) in its monimolimnion. As expected, the microbial ecology of this lake is greatly influenced by these conditions. A bacterium, Halanaerobium hydrogeniformans, was isolated from the mixolimnion region of this lake. Halanaerobium hydrogeniformans is a haloalkaliphilic bacterium capable of forming hydrogen from 5- and 6-carbon sugars derived from hemicellulose and cellulose. Due to its ability to produce hydrogen under saline and alkaline conditions, in amounts that rival genetically modified organisms, its genome was sequenced. This sequence data provides an opportunity to explore the unique metabolic capabilities of this organism, including the mechanisms for tolerating the extreme conditions of both high salinity and alkalinity of its environment.
Highlights
Soap Lake is a meromictic, haloalkaline lake located in Washington State
The distribution of the genes into clusters of orthologous groups (COGs) functional categories is provided in Figure 1 and Table 2
The gene count for the different Kyoto Encyclopedia of Genes and Genomes (KEGG) categories is similar between Halanaerobium hydrogeniformans and Halanaerobium praevalens GSLT except for a few categories (Table 2)
Summary
Soap Lake is a meromictic, haloalkaline lake located in Washington State. It thought that the aerobic and anaerobic layers of this lake have not mixed in over 2000 years (Peyton and Yonge, 2002). The lake’s meromictic characteristic is due to the steep gradient in salt concentrations between the mixolimnion and the monimolimnion, 15 gL−1 and 140 gL−1, respectively (Sorokin et al, 2007), and the shape of the lake’s basin (Edmondson and Anderson, 1965). It is the terminal lake in the chain of lakes that formed in the Lower Grand Coulee during the Missoula Floods. The concentrations of bicarbonates in Soap Lake were always found to be lower than the carbonates with 2000 mgL−1 in the mixolimnion and 4,800 mgL−1 in the monimolimnion (Anderson, 1958)
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