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The genus Halomonas possesses bacteria that are halophilic or halotolerant and exhibit a wide range of pH tolerance. The genome of Halomonas sp. Soap Lake #7 was sequenced to provide a better understanding of the mechanisms for salt and pH tolerance in this genus. The bacterium’s genome was found to possess two complete multiple resistance and pH antiporter systems, Group 1 and Group 2. This is the first report of both multiple resistance and pH antiporter Groups 1 and 2 in the genome of a haloalkaliphilic bacterium.

Aims Development of biomineralization technologies has largely focused on microbially induced carbonate precipitation (MICP) via Sporosarcina pasteurii ureolysis; however, as an obligate aerobe, the general utility of this organism is limited. Here, facultative and anaerobic haloalkaliphiles capable of ureolysis were enriched, identified and then compared to S. pasteurii regarding biomineralization activities. Methods and results Anaerobic and facultative enrichments for haloalkaliphilic and ureolytic micro-organisms were established from sediment slurries collected at Soap Lake (WA). Optimal pH, temperature and salinity were determined for highly ureolytic enrichments, with dominant populations identified via a combination of high-throughput SSU rRNA gene sequencing, clone libraries and Sanger sequencing of isolates. The enrichment cultures consisted primarily of Sporosarcina- and Clostridium-like organisms. Ureolysis rates and direct cell counts in the enrichment cultures were comparable to the S. pasteurii (strain ATCC 11859) type strain. Conclusions Ureolysis rates from both facultatively and anaerobically enriched haloalkaliphiles were either not statistically significantly different to, or statistically significantly higher than, the S. pasteurii (strain ATCC 11859) rates. Work here concludes that extreme environments can harbour highly ureolytic active bacteria with potential advantages for large scale applications, such as environments devoid of oxygen. Significance and impact of the study The bacterial consortia and isolates obtained add to the possible suite of organisms available for MICP implementation, therefore potentially improving the economics and efficiency of commercial biomineralization.

Soap Lake, located in Washington State, is a meromictic soda lake that was the subject of a prior National Science Foundation funded Microbial Observatory. Several organisms inhabiting this lake have been identified as producers of siderophores that are unique in structure. Two isolates found to be of the species Halomonas, SL01 and SL28, were found to produce suites of amphiphilic siderophores consisting of a peptidic head-group, which binds iron appended to fatty acid moieties of various lengths. The ability for siderophores to self-assemble into vesicles was determined for three suites of amphiphilic siderophores of unique structure (two from SL01 and one from SL28). These siderophores resemble the amphiphilic aquachelin siderophores produced by Halomonas aquamarina strain DS40M3, a marine bacterium. Vesicle self-assembly studies were performed by dynamic light scattering and epifluorescence microscopy. The addition of ferric iron (Fe3+) at different equivalents, where an equivalence of iron is defined as equal to the molarity of the siderophore, demonstrated vesicle formation. This was suggested by both dynamic light scattering and epifluorescence microscopy. Bacteria thriving under saline and alkaline conditions are capable of producing unique siderophores that self-assemble in micelles and vesicles due to ferric iron chelation.

Thioalkalimicrobium cyclicum Sorokin et al. 2002 is a member of the family Piscirickettsiaceae in the order Thiotrichales. The γ-proteobacterium belongs to the colourless sulfur-oxidizing bacteria isolated from saline soda lakes with stable alkaline pH, such as Lake Mono (California) and Soap Lake (Washington State). Strain ALM 1(T) is characterized by its adaptation to life in the oxic/anoxic interface towards the less saline aerobic waters (mixolimnion) of the stable stratified alkaline salt lakes. Strain ALM 1(T) is the first representative of the genus Thioalkalimicrobium whose genome sequence has been deciphered and the fourth genome sequence of a type strain of the Piscirickettsiaceae to be published. The 1,932,455bp long chromosome with its 1,684 protein-coding and 50 RNA genes was sequenced as part of the DOE Joint Genome Institute Community Sequencing Program (CSP) 2008.

Soap Lake, located in Washington State, is a naturally occurring saline and alkaline lake. Several organisms inhabiting this lake have been identified as producers of siderophores that are unique in structure. Bacterial isolates, enriched from Soap Lake sediment and water samples, were screened for siderophore production using both the chrome azurol S (CAS) agar plate and liquid methods. Bacterial isolate Halomonas sp. SL01 was found to produce relatively high concentrations of siderophores in liquid medium (up to 40 µM). Siderophores from the isolate were separated from the culture supernatant using solid phase extraction and purified by high-performance liquid chromatography (HPLC). Siderophore structure was determined using LC/MS/MS (liquid chromatography/mass spectrometry/mass spectrometry) and fatty acid methyl ester (FAME) GC. Two distinct new families of amphiphilic siderophores were produced by isolate SL01. All siderophores ranged in size from 989 to 1096 atomic mass units and consisted of a conserved peptidic head group (per family), which coordinates iron, coupled to fatty acid moieties. The fatty acyl moieties were C10–C14 in length and some with hydroxyl substitutions at the third α position. These siderophores resembled amphiphilic aquachelin siderophores produced by Halomonas aquamarina strain DS40M3, a marine bacterium as well as siderophores from isolate Halomonas sp. SL28 that was found to produce amphiphilic siderophores. Bacteria thriving under saline and alkaline conditions are capable of producing unique siderophores resembling those produced by microbes inhabiting marine environments.

Soap Lake is a small saline lake in central eastern Washington that is sharply stratified into two layers. In addition to being highly alkaline (~pH 10), Soap Lake also contains high concentrations of sulfide. Here, we report the community profile of the prokaryotic microbiota associated with Soap Lake surface water.

The microbial community diversity and composition of meromictic Soap Lake were studied using culture-dependent and culture-independent approaches. The water column and sediments were sampled monthly for a year. Denaturing gradient gel electrophoresis of bacterial and archaeal 16S rRNA genes showed an increase in diversity with depth for both groups. Late-summer samples harbored the highest prokaryotic diversity, and the bacteria exhibited less seasonal variability than the archaea. Most-probable-number assays targeting anaerobic microbial guilds were performed to compare summer and fall samples. In both seasons, the anoxic samples appeared to be dominated by lactate-oxidizing sulfate-reducing prokaryotes. High numbers of lactate- and acetate-oxidizing iron-reducing bacteria, as well as fermentative microorganisms, were also found, whereas the numbers of methanogens were low or methanogens were undetectable. The bacterial community composition of summer and fall samples was also assessed by constructing 16S rRNA gene clone libraries. A total of 508 sequences represented an estimated >1,100 unique operational taxonomic units, most of which were from the monimolimnion, and the summer samples were more diverse than the fall samples (Chao1 = 530 and Chao1 = 295, respectively). For both seasons, the mixolimnion sequences were dominated by Gammaproteobacteria , and the chemocline and monimolimnion libraries were dominated by members of the low-G+C-content group, followed by the Cytophaga-Flexibacter-Bacteroides (CFB) group; the mixolimnion sediments contained sequences related to uncultured members of the Chloroflexi and the CFB group. Community overlap and phylogenetic analyses, however, not only demonstrated that there was a high degree of spatial turnover but also suggested that there was a degree of temporal variability due to differences in the members and structures of the communities.

A halotolerant, alkaliphilic dissimilatory Fe(III)-reducing bacterium, strain SFB, was isolated from salt flat sediments collected from Soap Lake, WA. 16S ribosomal ribonucleic acid gene sequence analysis identified strain SFB as a novel Bacillus sp. most similar to Bacillus agaradhaerens (96.7% similarity). Strain SFB, a fermentative, facultative anaerobe, fermented various hexoses including glucose and fructose. The fructose fermentation products were lactate, acetate, and formate. Under fructose-fermenting conditions in a medium amended with Fe(III), Fe(II) accumulated concomitant with a stoichiometric decrease in lactate and an increase in acetate and CO(2). Strain SFB was also capable of respiratory Fe(III) reduction with some unidentified component(s) of Luria broth as an electron donor. In addition to Fe(III), strain SFB could also utilize nitrate, fumarate, or O(2) as alternative electron acceptors. Optimum growth was observed at 30 degrees C and pH 9. Although the optimal salinity for growth was 0%, strain SFB could grow in a medium with up to 15% NaCl by mass. These studies describe a novel alkaliphilic, halotolerant organism capable of dissimilatory Fe(III) reduction under extreme conditions and demonstrate that Bacillus species can contribute to the microbial reduction of Fe(III) in environments at elevated pH and salinity, such as soda lakes.

Culture-dependent and -independent techniques were used to study the diversity of chemolithoautotrophic sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake containing an unprecedentedly high sulfide concentration in the anoxic monimolimnion. Both approaches revealed the dominance of bacteria belonging to the genus Thioalkalimicrobium , which are common inhabitants of soda lakes. A dense population of Thioalkalimicrobium (up to 10 7 cells/ml) was found at the chemocline, which is characterized by a steep oxygen-sulfide gradient. Twelve Thioalkalimicrobium strains exhibiting three different phenotypes were isolated in pure culture from various locations in Soap Lake. The isolates fell into two groups according to 16S rRNA gene sequence analysis. One of the groups was closely related to T. cyclicum , which was isolated from Mono Lake (California), a transiently meromictic, haloalkaline lake. The second group, consisting of four isolates, was phylogenetically and phenotypically distinct from known Thioalkalimicrobium species and unique to Soap Lake. It represented a new species, for which we suggest the name Thioalkalimicrobium microaerophilum sp. nov.

Schmidt’s stability concept is used in a comparison of profiles of temperature and salinity for six meromictic lakes in 1953–4958 and 1972. The dual control of density in these lakes is emphasized by distinguishing “thermal” from “chemical” (or “meromictic”) stability. A slight modification of the Schmidt equation is made to yield a plot with depth of the minimum work required for destratification. Significant erosion of the salinity stratification has occurred in nearly all those lakes investigated, with consequent decreases in stability. Soap Lake, in the Lower Grand Coulee, has been considerably modified by dilution; one effect has been to prolong the existence of meromixis by at least 20 years.

The profiles of soluble fallout plutonium in two partially anoxic waters revealed minimum concentrations at the 02-H2S interface, indicating Pu removal onto particulate phases of Fe and other oxidized species that form during the redox cycle. In Saanich Inlet, an intermittently anoxic fjord in Vancouver Island, Canada, the concentration of soluble Pu in the anoxic zone was slightly less than in the oxygenated surface layer. In Soap Lake, a saline meromictic lake in eastern Washington State, Pu concentrations in the permanently anoxic zone were at least an order of magnitude higher than at the surface. Differences in the chemical characteristics of these two waters suggest important chemical species that influenced the observed Pu distribution. In the permanently anoxic zone of Soap Lake, high values of total alkalinity ranging from 940 to 1,500 meq liter-‘, sulfide species from 38 to 128 FM, dissolved organic carbon from 163 to 237 mg liter-‘, and total dissolved solids from 80 to 140 ppt, all correlated with the observed high concentration of Pu. In Saanich Inlet, where total alkalinity ranged from 2.1 to 2.4 meq liter-’ and salinity from 25 to 32%~ and H,S concentration in May 198 1 showed a maximum of 8 PM, the observed Pu concentrations were significantly lower than for the Soap Lake monimolimnion.

Soap Lake and Lake Lenore occupy adjacent basins in the Lower Grand Coulce, Washington, but show several strong limnological contrasts despite correspondence in rates and trends of heat storage. Seasonal events in the dynamics of phytoplankton and zooplankton populations generally coincide with different phases in thermal behavior of the lakes. Both lakes show a dramatic summer decline in phytoplankton population density, with spring and fall periods of more intense activity. In Soap Lake, which stratifies thermally in summer, a dense algal population is established in the metalimnion. The summer phytoplankton minima in both lakes coincide with maximum development of zooplankton populations, although there is no conclusive evidence that zooplankton grazing actually limits phytoplankton growth. The seasonal phytoplankton cycles may be more closely dependent on nutrient depletion in surface waters, and oxygen inhibition of photosynthesis might also be implicated. Close agreement was evident in 14C productivity measurements for both lakes, but these may have been affected by oxygen inhibition in light and dark bottles. Both lakes, however, are highly productive, and productivity estimates are comparable with those obtained for soda lakes elsewhere.

In the Lower Grand Coulee, Washington, Diaptomus nevadensis in Soap Lake contains larger amounts of the carotenoid astaxanthin than in Lake Lenore. During winter, Diaptomus sicilis contains larger amounts of pigment in both lakes, but in summer individuals from Lake Lenore are much reduced in pigment while those from Soap Lake are unchanged. The amount of astaxanthin might be a reflection of the amount of pigment in the copepods’ diet or might reflect the relative importance of selective forces acting for and against pigmentation, Seasonal variations in copepod carotenoid content did not correspond with variations in total lipid content. Algal abundance was measured by chlorophyll a and plant carotenoids correlated with copepod carotenoids only in the case of D. neuadensis in Soap Lake. The percent of D. nevadensis guts containing algae was correlated with their pigment content in both lakes. Visually oriented predators, such as damselfly nymphs from both lakes and salamander larvae from Lake Lenore, selected red copepods, but few predators from Lake Lenore contained D. nevadensis. Since members of this species were rare, the probability of finding a predator that had consumed one was low. When fed identical diets, copepods from Lake Lenore were a fifth to a thirtieth as efficient at assimilating carotenoid as those from Soap Lake. This supports the hypothesis that the pigment differences are the result of natural selection. Selective predation is implicated as the explanation for the small amounts of pigment in Lake Lenore copepods.

The central part of the State of Washington has an arid climate and contains a number of saline lakes. Several are meromictic and show a variety of vertical gradients of salinity and temperature. The mixolimnion of Soap Lake has been diluted by increased entry of freshwater from 39.4 g/liter in 1946 to 18.0 in 1964 while the monimolimnion has been maintained at more than 130 g/liter. The stability of the chemocline was studied by an injection of radioactive rubidium. The radioactivity spread laterally in all directions, mostly in a layer less than 2 m thick, to a maximum observed mean radius of 53 m in 13 days. The corresponding eddy diffusion coefficient is 3.2 cm2/sec.

Sediments from Soap Lake, an alkaline-saline lake on the arid Columbia Plateau, demonstrate postdepositional changes in response to a measured osmotic potential gradient through the sediment. The primary mechanism for osmotic readjustment is redistribution of water and dissolved ions through the sediment, altering scdimcnt water content and pore water salinity. This redistribution provides a mechanism for mobilizing ions from exchange sites and from minerals to form pore waters of altered composition, The historical record of aquatic ecosystems preserved in lake sediments provides information about the evolution of ecosystems and their reaction to environmental change. Microfossils are commonly used as indicators of a lake’s history, but in saline lakes, the biota is often limited, its members may exhibit a wide range of tolerance, and their preservation may be poor. In very saline lakes, a wealth of authigenic minerals can be used for environmental interpretation. In some lakes, however, the water is too saline to use microfossils, yet too dilute to exhibit many authigenic minerals; in such lakes the major record is in the salinity of the pore water. Sediments are multiphase systems; redistribution of ions can occur not only among the phases present in a sediment stratum but also between strata. Because of the likelihood of these postdepositional alterations, direct paleolimnological interpretation based on chemical and mineralogical characteristics of the sediment is difficult. The purpose of this study was to evaluate the usefulness of chemical characteristics of saline sediment for paleolimnological interpretation as well as the diagenetic mechanisms altering the saline sediment after deposition. l Supported by National Research Council of Canada Fellowships and National Science Foundation Grant GB 3567, 2 Present address: Division of Life Sciences, Scarborough College, University of Toronto, West Hill, Ontario. In saline sediments, an important diagenetic mechanism is the movement of water and dissolved ions up and down the sediment column. Because the rates are too slow to measure in the field, this movement has to be inferred indirectly. One approach is to measure sediment water potential. Sediment water potential ( @kACd) is defined as the difference between the chemical potential of water in the sediment ( JLC~) and the chemical potential of pure free water at the same temperature and pressure ( ~~0)) divided by the partial molal volume of water (V*,) to convert !Pksed to units of pressure (Kramer 1969) : !a scd = (j-b /-ho> /En. Since the chemical potential of a system is a measure of its capacity to do work, the sediment water potential gradient defines the direction in which water can move spontaneously: water will move from sediment with a high sediment water potential to sediment with a lower potential. The sediment water potential expression can be written as !I! scd RTln ’ =v*W& [ 1 ,o where e is the vapor pressure of water in the sediment and e” the vapor pressure of pure free water at the same temperature and pressure ( Kramer 1969). Thus, .by measuring the vapor pressure of water in the sediment, we can measure the water potential of the sediment and define the LIMNOLOGY AND OCEANOGRAPHY 403 MAY 1973, V. H(3) 404 MARK A. MANTUANI potential gradients that control the direction of movement of water in the sediment, This concept has been used to study the dynamics of salt and water movement in the soil-plant system, and it seems natural to apply it to readjusting wet, unconsolidated saline sediment. It emphasizes the colligative properties of the system rather than simply focusing on the vertical distribution of a few ions, Finally, sediment water potential allows integration of the various mechanisms that can cause water movement, i. e. !?? sea = *k,n + $I + *k, + *k,, where ek,, is matric or capillary potential, *, is pressure potential, !lXk, is osmotic or solute potential, and 9, is gravitational potential. Since many of these components are most easily expressed in terms of pressure units, it is useful to have +\ksed also expressed as pressure, rather than as the activity of water. Soap Lake, an alkaline-saline lake in the Lower Grand Coulee, Washington, lies in the Columbia Basin, in the rainshadow of the Cascade Mountains. Annual rainfall is less than 25 cm per year, and the potential evaporation is greater than the precipitation throughout the year ( Gilkeson 1962). The Grand Coulee was formed by the Columbia River when it was diverted from its regular channel by ice dams formed during the Wisconsin glaciation; upon retreat of the glacier at the end of the Pinedale glaciation, the last substage of the Wisconsin, the Columbia river reoccupied its old channel, leaving a series of lakes in the coulee (Richmond et al. 1965). The level of Soap Lake, the southernmost lake in the series, dropped below its outlet 11,000 years ago, and the lake rapidly became saline. In the last 20 years alteration of the hydrology of this basin by the Columbia Irrigation Project has significantly diluted Soap Lake (Friedman and Redfield 1971). I chose the sediments of Soap Lake for this study because they should record both its evolution from a dilute periglacial lake to an alkaline-saline lake and the recent dilution.

included in the Columbia Basin Project, the largest single irrigation plan ever conceived. Grant County is large, almost a hundred miles long and fifty miles wide. Within the area has been one of the sparsest populations of the state, yet few agricultural regions have had greater changes resulting from war conditions. What the future will bring when the Columbia Basin Project has been completed and thousands of farms are developed in the region, it is difficult to conjecture. Physically, the county is a southsloping, semi-arid plateau with elevation varying between 1000 and 2000 feet. The county is divided into five parts on the basis of its soils and topography: the Channeled Scablands, the Waterville Plateau, the Quincy Flats, the Folded Ridges, and the Sand Hills. The Channeled Scablands is largest of the five parts occupying the northern and eastern half of the county to the north and east of Soap Lake, Ephrata, and Moses Lake (see map). The scablands are glacial channels left by meltwater of the ice sheet which covered