SEARCH · PubMed Health

Results for “hypersalinity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

PubMed2005

Methylohalobius crimeensis gen. nov., sp. nov., a moderately halophilic, methanotrophic bacterium isolated from hypersaline lakes of Crimea.

A novel genus and species are proposed for two strains of methanotrophic bacteria isolated from hypersaline lakes in the Crimean Peninsula of Ukraine. Strains 10Ki(T) and 4Kr are moderate halophiles that grow optimally at 1-1.5 M (5.8-8.7%, w/v) NaCl and tolerate NaCl concentrations from 0.2 M up to 2.5 M (1.2-15%). This optimum and upper limit are the highest for any methanotrophic bacterium known to date. The strains are Gram-negative, aerobic, non-pigmented, motile, coccoid to spindle-shaped bacteria that grow on methane or methanol only and utilize the ribulose monophosphate pathway for carbon assimilation. They are neutrophilic (growth occurs only in the range pH 6.5-7.5) and mesophilic (optimum growth occurs at 30 degrees C). On the basis of 16S rRNA gene sequence phylogeny, strains 10Ki(T) and 4Kr represent a type I methanotroph within the 'Gammaproteobacteria'. However, the 16S rRNA gene sequence displays <91.5 % identity to any public-domain sequence. The most closely related methanotrophic bacterium is the thermophilic strain HB. The DNA G+C content is 58.7 mol%. The major phospholipid fatty acids are 18:1omega7 (52-61%), 16:0 (22-23%) and 16:1omega7 (14-20%). The dominance of 18:1 over 16:0 and 16:1 fatty acids is unique among known type I methanotrophs. The data suggest that strains 10Ki(T) and 4Kr should be considered as belonging to a novel genus and species of type I methanotrophic bacteria, for which the name Methylohalobius crimeensis gen. nov., sp. nov. is proposed. Strain 10Ki(T) (=DSM 16011(T)=ATCC BAA-967(T)) is the type strain.

Bacterial Typing Techniques↗

PubMed2005

Roseisalinus antarcticus gen. nov., sp. nov., a novel aerobic bacteriochlorophyll a-producing alpha-proteobacterium isolated from hypersaline Ekho Lake, Antarctica.

A Gram-negative, aerobic to microaerophilic rod was isolated from 10 m depths of the hypersaline, heliothermal and meromictic Ekho Lake (East Antarctica). The strain was oxidase- and catalase-positive, metabolized a variety of carboxylic acids and sugars and produced lipase. Cells had an absolute requirement for artificial sea water, which could not be replaced by NaCl. A large in vivo absorption band at 870 nm indicated production of bacteriochlorophyll a. The predominant fatty acids of this organism were 16 : 0 and 18 : 1omega7c, with 3-OH 10 : 0, 16 : 1omega7c and 18 : 0 in lower amounts. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylcholine. Ubiquinone 10 was produced. The DNA G+C content was 67 mol%. 16S rRNA gene sequence comparisons indicated that the isolate represents a member of the Roseobacter clade within the alpha-Proteobacteria. The organism showed no particular relationship to any members of this clade but clustered on the periphery of the genera Jannaschia, Octadecabacter and 'Marinosulfonomonas' and the species Ruegeria gelatinovorans. Distinct morphological, physiological and genotypic differences to these previously described taxa supported the description of a new genus and a novel species, for which the name Roseisalinus antarcticus gen. nov., sp. nov. is proposed. The type strain is EL-88T (=DSM 11466T=CECT 7023T).

Aerobiosis↗

PubMed2005

Idiomarina seosinensis sp. nov., isolated from hypersaline water of a solar saltern in Korea.

A halophilic gamma-proteobacterium, designated CL-SP19T, was isolated from hypersaline water from a solar saltern located in Seosin, Korea. Analysis of the 16S rRNA gene sequence revealed an affiliation with the genus Idiomarina. The sequence similarities between CL-SP19T and type strains of the genus Idiomarina ranged from 95.9 to 96.9 %. Cells were straight or slightly curved rods and were motile by means of a single polar flagellum. The major fatty acids were C(15 : 0) iso (17.1 %) and C(17 : 0) iso (15.2 %). Three fatty acids, C(19 : 0)omega8c cyclo (3.5 %), C(14 : 1)omega5c (1.4 %) and C(18 : 3)omega6c (1.2 %), were found in minor quantities, but uniquely in CL-SP19T among Idiomarina species. The DNA G+C content was 45.0 mol%. On the basis of its physiology, fatty acid composition and 16S rRNA gene sequence, strain CL-SP19T could be assigned to the genus Idiomarina but distinguished from the recognized species of the genus. Strain CL-SP19T, therefore, represents a novel species, for which the name Idiomarina seosinensis sp. nov. is proposed, with CL-SP19T (=KCTC 12296T=JCM 12526T) as the type strain.

Bacterial Typing Techniques↗

PubMed2006

Nesiotobacter exalbescens gen. nov., sp. nov., a moderately thermophilic alphaproteobacterium from an Hawaiian hypersaline lake.

A Gram-negative bacterium, designated LA33B(T), was isolated from water collected from a hypersaline lake on uninhabited Laysan Atoll in the Northwestern Hawaiian Islands. Cells of strain LA33B(T) are motile, straight rods that grow between 4 and 45 degrees C and in media containing 1-17.5% (w/v) NaCl. The strain oxidizes carbohydrates, nucleosides, amino acids and organic acids presented as sole carbon sources and constitutive lipolytic and proteolytic enzymes are expressed. Over 75% of the fatty acid pool is cis-11-octadecenoic acid (18:1omega7c). Comparative sequence analysis of the 16S rRNA gene indicates that the strain forms a new lineage in the alpha-2 subclass of the Proteobacteria, with the closest recognized strains being Stappia aggregata NCIMB 2208T and Roseibium denhamense JCM 10543T, with which it shares 94-95% sequence similarity. Strain LA33B(T) differs phenotypically from extant Stappia and Roseibium species, however, in that it is a moderate thermophile, it requires NaCl and tolerates higher NaCl concentrations and it does not express beta-galactosidase or oxidize glycerol. On the basis of genotypic data and phenotypic characteristics, we propose that strain LA33B(T) does not belong to the genera Stappia or Roseibium and that it represents the type species of a new genus, Nesiotobacter. Strain LA33B(T) (= ATCC BAA-994T = CIP 108449T) is proposed as the type strain of the type species of this genus, with the name Nesiotobacter exalbescens gen. nov., sp. nov.

Alphaproteobacteria↗

PubMed2006

Jannaschia seosinensis sp. nov., isolated from hypersaline water of a solar saltern in Korea.

A slightly halophilic alphaproteobacterium, designated CL-SP26T, was isolated from hypersaline water of a solar saltern located in Seosin, Korea. 16S rRNA gene sequence analysis revealed an affiliation with the genus Jannaschia. Sequence similarities between CL-SP26T and type strains of members of the genus Jannaschia were 94.9-97.2 %. Cells were rod-shaped and motile with one or more monopolar flagella. Strain CL-SP26T grew on solid media as circular red colonies. It was able to grow in 3-10 % sea salt; however, no growth occurred in media containing NaCl as the only salt. Strain CL-SP26T grew at 5-35 degrees C and pH 7-10. The major fatty acids were 18 : 1omega7c (64 %) and 18 : 0 (12.0 %). Three fatty acids, 3-OH 14 : 0/iso 16 : 1 (3.6 %), 18 : 3omega6c (2.2 %) and 10-methyl 19 : 0 (1.9 %), found in minor quantities in CL-SP26(T), are unique among Jannaschia species. The DNA G+C content was 63 mol%. According to physiological data, fatty acid composition and 16S rRNA gene sequence analysis, CL-SP26T was assigned to the genus Jannaschia, but could be distinguished from recognized species of the genus. Strain CL-SP26T (= KCCM 42114T = JCM 13035T) therefore represents a novel species, for which the name Jannaschia seosinensis sp. nov. is proposed.

Alphaproteobacteria↗

PubMed2006

Extremely halophilic denitrifying bacteria from hypersaline inland lakes, Halovibrio denitrificans sp. nov. and Halospina denitrificans gen. nov., sp. nov., and evidence that the genus name Halovibrio Fendrich 1989 with the type species Halovibrio variabilis should be associated with DSM 3050.

Anaerobic enrichments with acetate as electron donor and nitrate as electron acceptor at 4 M NaCl from inland, hypersaline lake sediments from Central Asia resulted in the isolation of several extremely halophilic bacteria that comprised two subgroups, most with vibrio-shaped cells and a single strain with rod-shaped cells. Members of both subgroups were extremely halophilic, with growth occurring in 2-5 M NaCl with an optimum at 2-3 M. 16S rRNA gene sequence analysis showed a close affiliation of the new isolates with Pseudomonas halophila DSM 3050 in the Gammaproteobacteria. However, phenotypic comparison of the denitrifying halophiles with the original description of P. halophila demonstrated that they were more similar to another bacterium isolated from the same source at the same time, the extremely halophilic Halovibrio variabilis, which has since been reclassified as Halomonas variabilis (DSM 3051). Direct cross-comparison showed that the characteristics of these two halophilic bacteria do not correspond with the original descriptions associated with these names and DSM numbers. While it is desirable that this problem be solved, in connection with the present investigations, this is a matter that can only be solved by a Request for an Opinion. On the basis of the phenotypic and genetic comparison of these isolates, it is proposed that the new denitrifying vibrio-shaped isolates represent a novel species, Halovibrio denitrificans sp. nov. (type strain HGD 3T=DSM 15503T=UNIQEM U232T) and that the rod-shaped isolate represents a novel genus and species, Halospina denitrificans gen. nov., sp. nov. (type strain HGD 1-3T=DSM 15505T=UNIQEM U233T).

Bacterial Typing Techniques↗

PubMed2006

Five novel species of the genus Nocardiopsis isolated from hypersaline soils and emended description of Nocardiopsis salina Li et al. 2004.

Five novel Nocardiopsis strains isolated from hypersaline soils in China were subjected to a polyphasic analysis to determine their taxonomic position. All of the novel isolates could grow on agar plates at NaCl concentrations of up to 18 % (w/v), with optimum growth at 5-8 %. The DNA G+C contents of the novel strains ranged from 67.9 to 73.2 mol%. The morphological and chemotaxonomic characteristics of the isolates matched those described for members of the genus Nocardiopsis. Based on their 16S rRNA gene sequence analysis, DNA-DNA hybridization values and phenotypic characteristics, including the composition of cell-wall amino acids and sugars, menaquinones, polar lipids and cellular fatty acids, the isolates are proposed as representing five novel species of the genus Nocardiopsis. The novel species are proposed as Nocardiopsis gilva sp. nov. [type strain YIM 90087T (=KCTC 19006T=CCTCC AA 2040012T=DSM 44841T)], Nocardiopsis rosea sp. nov. [type strain YIM 90094T (=KCTC 19007T=CCTCC AA 2040013T=DSM 44842T), Nocardiopsis rhodophaea sp. nov. [type strain YIM 90096T (=KCTC 19049T=CCTCC AA 2040014T=DSM 44843T), Nocardiopsis chromatogenes sp. nov. [type strain YIM 90109T (=KCTC 19008T=CCTCC AA 2040015T=DSM 44844T) and Nocardiopsis baichengensis sp. nov. [type strain YIM 90130T (=KCTC 19009T=CCTCC AA 2040016T=DSM 44845T). On the basis of the chemotaxonomic data, the description of the recently described species Nocardiopsis salina Li et al. 2004 is emended.

Actinomycetales↗

PubMed2006

Thiomicrospira halophila sp. nov., a moderately halophilic, obligately chemolithoautotrophic, sulfur-oxidizing bacterium from hypersaline lakes.

Enrichments at 2 M NaCl and pH 7.5-8, with thiosulfate or sulfide as electron donor, inoculated with sediments from hypersaline chloride-sulfate lakes of the Kulunda Steppe (Altai, Russia) resulted in the domination of two different groups of moderately halophilic, chemolithoautotrophic, sulfur-oxidizing bacteria. Under fully aerobic conditions with thiosulfate, bacteria belonging to the genus Halothiobacillus dominated while, under microaerophilic conditions, a highly motile, short vibrio-shaped phenotype outcompeted the halothiobacilli. Three genetically and phenotypically highly similar vibrio-shaped isolates were obtained in pure culture and one of them, strain HL 5(T), was identified as a member of the Thiomicrospira crunogena cluster by 16S rRNA gene sequencing. The new isolates were able to grow with thiosulfate as electron donor within a broad salinity range from 0.5 to 3.5 M NaCl with an optimum at 1.5 M and within a pH range from 6.5 to 8.5 with an optimum at pH 7.5-7.8. Comparative analysis of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) gene sequences demonstrated that strain HL 5(T) possessed two genes, cbbL-1 and cbbL-2, of the form I RuBisCO and a cbbM gene of the form II RuBisCO, similar to the other members of the Thiomicrospira crunogena cluster. On the basis of phenotypic and genetic comparison, the new halophilic isolates are proposed to be placed into a novel species, Thiomicrospira halophila sp. nov. (type strain HL 5(T)=DSM 15072(T)=UNIQEM U 221(T)).

Bacterial Typing Techniques↗

PubMed2006

Diversity of culturable halophilic sulfur-oxidizing bacteria in hypersaline habitats.

Unexpectedly high culturable diversity of moderately and extremely halophilic obligately chemolithoautotrophic sulfur-oxidizing bacteria (SOB) was discovered in the sediments of various hypersaline habitats, including chloride-sulfate lakes in Mongolia, Russia and Ukraine, a sea saltern in Slovenia and a deep-sea salt brine from the Mediterranean. Six different groups of halophilic SOB, including four new genera, all belonging to the Gammaproteobacteria, were found. Two groups of moderately halophilic strictly aerobic SOB dominated at 2 M NaCl, including representatives of the genus Halothiobacillus (in fully aerobic conditions) and Thiomicrospira (in micro-oxic conditions). Under denitrifying conditions at 2 M NaCl, a group of moderately halophilic and facultatively anaerobic SOB was selected, capable of complete denitrification of nitrate. The group represents a new genus with closest relatives among as yet undescribed marine thiodenitrifying isolates. With thiocyanate as a substrate, an enrichment culture at 2 M NaCl yielded a pure culture of moderately halophilic SOB capable of aerobic growth with thiocyanate and thiosulfate at up to 4 M NaCl. Furthermore, this bacterium also grew anaerobically using nitrite as electron acceptor. It formed a new lineage distantly related to the genus Thiomicrospira. Enrichments at 4 M NaCl resulted in the domination of two different, previously unknown, groups of extremely halophilic SOB. Under oxic conditions, they were represented by strictly aerobic spiral-shaped bacteria, related to the Ectothiorhodospiraceae, while under denitrifying conditions a group of facultatively anaerobic nitrate-reducing bacteria with long rod-shaped cells was selected, distantly related to the genus Acidithiobacillus.

Aerobiosis↗

PubMed2004

Microbial diversity of extant stromatolites in the hypersaline marine environment of Shark Bay, Australia.

Stromatolites have been present on Earth, at various levels of distribution and diversity, for more than 3 billion years. Today, the best examples of stromatolites forming in hypersaline marine environments are in Hamelin Pool at Shark Bay, Western Australia. Despite their evolutionary significance, little is known about their associated microbial communities. Using a polyphasic approach of culture-dependent and culture-independent methods, we report the discovery of a wide range of microorganisms associated with these biosedimentary structures. There are no comparable reports combining these methodologies in the survey of cyanobacteria, bacteria, and archaea in marine stromatolites. The community was characterized by organisms of the cyanobacterial genera Synechococcus, Xenococcus, Microcoleus, Leptolyngbya, Plectonema, Symploca, Cyanothece, Pleurocapsa and Nostoc. We also report the discovery of potentially free-living Prochloron. The other eubacterial isolates and clones clustered into seven phylogenetic groups: OP9, OP10, Marine A group, Proteobacteria, Low G+C Gram-positive, Planctomycetes and Acidobacteria. We also demonstrate the presence of sequences corresponding to members of halophilic archaea of the divisions Euryarchaeota and Crenarchaeota and methanogenic archaea of the order Methanosarcinales. This is the first report of such archaeal diversity from this environment. This study provides a better understanding of the microbial community associated with these living rocks.

Archaea↗

PubMed2007

Comparison of chitinolytic enzymes from an alkaline, hypersaline lake and an estuary.

We examined the genetic and physiological characteristics of chitin degrading enzymes expressed by fosmids cloned from two strains of chitinolytic gammaproteobacteria isolated from alkaline, hypersaline Mono Lake, California; and from a metagenomic library derived from an estuarine bacterial community (Dean Creek, Sapelo Island, GA, USA). The Mono Lake chitinolytic enzymes presented unique adaptations in terms of halo- and alkalitolerance. The sequence from one of the Mono Lake isolates (strain 12A) was a conventional family 18 glycosyl hydrolase; however, the expressed protein had a novel secondary activity peak at pH 10. We obtained a novel family 20 glycosyl hydrolase sequence from Mono Lake strain AI21. The activity of the expressed protein had a pH optimum of 10, several pH units higher than any other enzyme currently assigned to this family, and the enzyme retained 80% of its activity at pH 11. The enzyme was also halotolerant, retaining activity in salt solutions of up to 225 g l(-1). Sequence analysis indicated a molecular weight of approximately 90 kDa for the protein, and that it contained two active sites. Culture supernatant contained two chitinolytic proteins, 45 and 31 kDa, suggesting possible post-expression modification of the gene product. In contrast, the sequence found in the estuarine metagenomic library and the functional characteristics of the protein expressed from it were those of a conventional family 18 glycosyl hydrolase.

Amino Acid Sequence↗

PubMed2006

Limitation of oxygenic photosynthesis and oxygen consumption by phosphate and organic nitrogen in a hypersaline microbial mat: a microsensor study.

Microbial mats are characterized by high primary production but low growth rates, pointing to a limitation of growth by the lack of nutrients or substrates. We identified compounds that instantaneously stimulated photosynthesis rates and oxygen consumption rates in a hypersaline microbial mat by following the short-term response (c. 6 h) of these processes to addition of nutrients, organic and inorganic carbon compounds, using microsensors. Net photosynthesis rates were not stimulated by compound additions. However, both gross photosynthesis and oxygen consumption were substantially stimulated (by a minimum of 25%) by alanine (1 mM) and glutamate (3.5 mM) as well as by phosphate (0.1 mM). A low concentration of ammonium (0.1 mM) did not affect photosynthesis and oxygen consumption, whereas a higher concentration (3.5 mM) decreased both process rates. High concentrations of glycolate (5 mM) and phosphate (1 mM) inhibited gross photosynthesis but not oxygen consumption, leading to a decrease of net photosynthesis. Photosynthesis was not stimulated by addition of inorganic carbon, nor was oxygen consumption stimulated by organic compounds like glycolate (5 mM) or glucose (5 mM), indicating that carbon was efficiently cycled within the mat. Photosynthesis and oxygen consumption were apparently tightly coupled, because stimulations always affected both processes to the same extent, which resulted in unchanged net photosynthesis rates. These findings illustrate that microsensor techniques, due to their ability to quantify all three processes, can clarify community responses to nutrient enrichment studies much better than techniques that solely monitor net fluxes.

Biosensing Techniques↗

PubMed2006

Vertical migration of phototrophic bacterial populations in a hypersaline microbial mat from Salins-de-Giraud (Camargue, France).

The spatio-temporal distribution of phototrophic communities of the hypersaline photosynthetic Camarguc microbial mat (Salins-de-Giraud, France) was investigated over a diel cycle by combining microscopic and molecular approaches. Microcoleus chthonoplastes and Halomicronema excentricum, the dominant cyanobacteria of this oxyphotrophic community, were observed with confocal laser scanning microscopy to determine their biomass profiles. Both bacteria have similar vertical distributions, varying from a homogenous distribution through the mat during the night, to a specific localization in the upper oxic zone of 1.5 mm during the day. Terminal restriction fragment length polymorphism of PCR-amplified pufM gene fragments revealed three groups of anoxyphototrophic populations, which varied according to the two opposite periods of the diel cycle under study. They were either specifically detected in only one period, or homogenously distributed through the mat in all periods, or located in specific zones of the mat depending on the period considered. Oxygen concentrations, pH and biomass of the major filamentous cyanobacteria were the determinative factors in the distribution of these anoxyphototrophs across the mat. Thus, vertical migration, cell-cell aggregate formation and metabolic switches were the most evident defence of the photosynthetic populations against the adverse effects of sulfide and oxygen fluxes during a diel cycle.

Biomass↗

PubMed2002

Mycosporine-2-glycine is the major mycosporine-like amino acid in a unicellular cyanobacterium (Euhalothece sp.) isolated from a gypsum crust in a hypersaline saltern pond.

Mycosporine-like amino acids (MAAs) were extracted from a unicellular cyanobacterium (Euhalothece sp.) isolated from a gypsum crust on the bottom of a hypersaline saltern pond in Eilat, Israel. When grown at high light intensities, this isolate contained high concentrations of two MAAs, one showing maximum optical density at 331 nm and one at 362 nm. The compound absorbing at 331 nm was purified by preparative high performance liquid chromatography, and its structure was elucidated by one-dimensional ((1)H and (13)C) and two-dimensional nuclear magnetic resonance, mass spectrometry and amino acid analysis, and identified as mycosporine-2-glycine. This is the first report of mycosporine-2-glycine in cyanobacteria.

Amino Acids↗

PubMed1998

Survival strategies for microorganisms in hypersaline environments and their relevance to life on early Mars.

There are two groups of microorganisms that live and grow in hypersaline (>10-15% NaCl) environments: the halophilic Archaea and the halotolerant Bacteria and algae. In order to grow and reproduce in such high-salt, low-water activity environments, these organisms have made basic biochemical adaptations in their proteins, osmoregulation mechanisms, nucleic acids, and lipids. The environment of the halophiles and especially how the halophilic Archaea have adapted to that environment are reviewed in this paper. Along with this review is a brief description of how these adaptations could be important in the detection of life on early Mars assuming similar types of salts and a carbon-based life.

Adaptation, Biological↗

PubMed2006

An anaerobic methane-oxidizing community of ANME-1b archaea in hypersaline Gulf of Mexico sediments.

Sediments overlying a brine pool methane seep in the Gulf of Mexico (Green Canyon 205) were analyzed using molecular and geochemical approaches to identify geochemical controls on microbial community composition and stratification. 16S rRNA gene and rRNA clone libraries, as well as mcrA gene clone libraries, showed that the archaeal community consists predominantly of ANME-1b methane oxidizers; no archaea of other ANME subgroups were found with general and group-specific PCR primers. The ANME-1b community was found in the sulfate-methane interface, where undersaturated methane concentrations of ca. 100 to 250 microM coexist with sulfate concentrations around 10 mM. Clone libraries of dsrAB genes and bacterial 16S rRNA genes show diversified sulfate-reducing communities within and above the sulfate-methane interface. Their phylogenetic profiles and occurrence patterns are not linked to ANME-1b populations, indicating that electron donors other than methane, perhaps petroleum-derived hydrocarbons, drive sulfate reduction. The archaeal component of anaerobic oxidation of methane is comprised of an active population of mainly ANME-1b in this hypersaline sediment.

Anaerobiosis↗

PubMed1978

Hydrocarbon biodegradation in hypersaline environments.

When mineral oil, hexadecane, and glutamate were added to natural samples of varying salinity (3.3 to 28.4%) from salt evaporation ponds and Great Salt Lake, Utah, rates of metabolism of these compounds decreased as salinity increased. Rate limitations did not appear to relate to low oxygen levels or to the availability of organic nutrients. Some oxidation of l-[U-C]glutamic acid occurred even at extreme salinities, whereas oxidation of [1-C]hexadecane was too low to be detected. Gas chromatographic examination of hexane-soluble components of tar samples from natural seeps at Rozel Point in Great Salt Lake demonstrated no evidence of biological oxidation of isoprenoid alkanes subject to degradation in normal environments. Some hexane-soluble components of the same tar were altered by incubation in a low-salinity enrichment culture inoculated with garden soil. Attempts to enrich for microorganisms in saline waters able to use mineral oil as a sole source of carbon and energy were successful below, but not above, about 20% salinity. This study strongly suggests a general reduction of metabolic rate at extreme salinities and raises doubt about the biodegradation of hydrocarbons in hypersaline environments.

Journal Article↗

PubMed1979

Microbial biomass and activity distribution in an anoxic, hypersaline basin.

The Orca Basin is a hypersaline depression in the northern Gulf of Mexico with anoxic conditions observed in the lower 200 m of the water column. Measurements of adenosine 5'-triphosphate, heterotrophic potential, and uridine uptake made above and across the interface into the anoxic zone revealed the presence of an active microbial population approximately 100 m above the interface. Biomass and activity decreased at and just below the interface but increased near the bottom, consistent with similar observations made in the Cariaco Trench. The maximum adenosine 5'-triphosphate concentration above the interface of 5.9 ng/liter (2,173 m) is about eight times greater than the value found in oxygenated waters of corresponding depth in the absence of an anoxic zone. The maximum adenosine 5'-triphosphate concentration in the anoxic zone is approximately 15 times greater than that found in oxygenated water of similar depth, suggesting anoxia will support the development of a larger bacterial population. Our findings suggest that autotrophic bacteria may be the dominant physiological group in the region just above the interface.

Journal Article↗