Composition of freshwater bacterial communities associated with cyanobacterial blooms in four Swedish lakes

The diversity of freshwater bacterioplankton communities has not been extensively studied despite their key role in foodwebs and the cycling of carbon and associated major elements. In order to explore and characterize the composition of bacterioplankton associated with cyanobacterial blooms, large 16S rRNA clone libraries from four lakes experiencing such blooms were analysed. The four libraries contained 1461 clones, of which 559 were prokaryotic sequences of non-cyanobacterial origin. These clones were classified into 158 operational taxonomic units affiliated mainly with bacterial divisions commonly found in freshwater systems, e.g. Proteobacteria, Bacteriodetes, Actinobacteria, Verrucomicrobia and Planctomycetes. Richness and evenness of non-cyanobacterial clones were similar to other clone libraries obtained for freshwater bacterioplankton, suggesting that bacterial communities accompanying cyanobacterial blooms are as diverse as non-bloom communities. Many of the identified operational taxonomic units grouped with known freshwater clusters but the libraries also contained novel clusters of bacterial sequences that may be characteristic for cyanobacterial blooms. About 25% of the operational taxonomic units were detected in more than one lake. Even so, 16S rRNA heterogeneity analysis demonstrated large differences in community composition between lakes regardless of their similar characteristics and close proximity. Hence even the similar environmental conditions created by different cyanobacterial blooms may foster very dissimilar bacterial communities, which could indicate that the genetic diversity in lake bacteria have been underestimated in the past.     

Phylotype diversity in a benthic cyanobacterial mat community on King George Island, maritime Antarctica

Cyanobacterial 16S ribosomal RNA gene diversity was examined in a benthic mat on Fildes Peninsula of King George Island (62o09′54.4′′S, 58o57′20.9′′W), maritime Antarctica. Environmental DNA was isolated from the mat, a clone library of PCR-amplified 16S rRNA gene fragments was prepared, and amplified ribosomal DNA restriction analysis (ARDRA) was done to assign clones to seven groups. Low cyanobacterial diversity in the mat was suggested in that 83% of the clones were represented by one ARDRA group. DNA sequences from this group had high similarity with 16S rRNA genes of Tychonema bourrellyi and T. bornetii isolates, whose geographic origins were southern Norway and Northern Ireland. Cyanobacterial morphotypes corresponding to Tychonema have not been reported in Antarctica, however, this morphotype was previously found at Ward Hunt Lake (83oN), and in western Europe (52oN). DNA sequences of three of the ARDRA groups had highest similarity with 16S rDNA sequences of the Tychonema group accounting for 9.4% of the clones. Sequences of the remaining three groups (7.6%) had highest similarity with 16S rRNA genes of uncultured cyanobacteria clones from benthic mats of Lake Fryxell and fresh meltwater on the McMurdo Ice Shelf.     

Microbes in high arctic snow and implications for the cold biosphere

We applied molecular, microscopic, and culture techniques to characterize the microbial communities in snow and air at remote sites in the Canadian High Arctic (Ward Hunt Island, Ellesmere Island, and Cornwallis Island, latitudes 74 to 83(o)N). Members of the Bacteria and Eukarya were prevalent in the snow, and their small subunit (SSU) rRNA gene signatures indicated strong local aerial transport within the region over the preceding 8 months of winter snowpack accumulation. Many of the operational taxonomic units (OTUs) were similar to previously reported SSU rRNA gene sequences from the Arctic Ocean, suggesting the importance of local aerial transport processes for marine microbiota. More than 47% of the cyanobacterial OTUs in the snow have been previously found in microbial mats in the region, indicating that this group was also substantially derived from local sources. Viable cyanobacteria isolated from the snow indicated free exchange between the snow and adjacent mat communities. Other sequences were most similar to those found outside the Canadian Arctic but were from snow, lake and sea ice, glaciers and permafrost, alpine regions, Antarctica, and other regions of the Arctic, supporting the concept of global distribution of microbial ecotypes throughout the cold biosphere.     

Ecosystems on ice: the microbial ecology of Markham Ice Shelf in the high Arctic

Microbial communities occur throughout the cryosphere in a diverse range of ice-dominated habitats including snow, sea ice, glaciers, permafrost, and ice clouds. In each of these environments, organisms must be capable of surviving freeze-thaw cycles, persistent low temperatures for growth, extremes of solar radiation, and prolonged dormancy. These constraints may have been especially important during global cooling events in the past, including the Precambrian glaciations. One analogue of these early Earth conditions is the thick, landfast sea ice that occurs today at certain locations in the Arctic and Antarctic. These ice shelves contain liquid water for a brief period each summer, and support luxuriant microbial mat communities. Our recent studies of these mats on the Markham Ice Shelf (Canadian high Arctic) by high performance liquid chromatography (HPLC) showed that they contain high concentrations of chlorophylls a and b, and several carotenoids notably lutein, echinenone and beta-carotene. The largest peaks in the HPLC chromatograms were two UV-screening compounds known to be produced by cyanobacteria, scytonemin, and its decomposition product scytonemin-red. Microscopic analyses of the mats showed that they were dominated by the chlorophyte genera cf. Chlorosarcinopsis, Pleurastrum, Palmellopsis, and Bracteococcus, and cyanobacteria of the genera Nostoc, Phormidium, Leptolyngbya, and Gloeocapsa. From point transects and localized sampling we estimated a total standing stock on this ice shelf of up to 11,200 tonnes of organic matter. These observations underscore the ability of microbial communities to flourish despite the severe constraints imposed by the cryo-ecosystem environment.     

免培养法研究野生川金丝猴肠道内生细菌多样性

【目的】了解野生川金丝猴(Rhinopithecus roxellana)肠道内生细菌的组成及其多样性。【方法】提取川金丝猴肠道内生细菌总DNA,选用细菌通用引物799F和1492R对总DNA进行16S rRNA基因特异性扩增,构建川金丝猴肠道内生细菌16S rRNA基因克隆文库,对阳性克隆进行限制性内切酶片段长度多态性(PCR-RFLP)分析,并对HaeⅢ酶切带谱菌株进行测序,构建系统发育树。【结果】根据酶切带谱分析和测序结果,将随机挑取的157个阳性克隆归为27个不同的可操作分类单元(OTUs)。系统发育分析表明这些克隆序列有62.10%属于厚壁菌门(Firmicutes),其中包括梭菌属(Clostridium)、Cellulosilyticum属、Robinsoniella属、Anaerofustis属、Blautia属和Anaerovorax属,有37.90%属于未培养细菌。【结论】川金丝猴肠道内生细菌多样性丰富,并且可能存在新的分类单元。     

Molecular analysis of the bacterial community in a continental high-temperature and water-flooded petroleum reservoir

Water from a continental high-temperature, long-term water-flooded petroleum reservoir in Huabei Oilfield in China was analysed for its bacterial community and diversity. The bacteria were characterized by their 16S rRNA genes. A 16S rRNA gene clone library was constructed from the community DNA, and using restriction fragment length polymorphism analysis, 337 randomly selected clones were clustered with 74 operational taxonomic units. Sequencing and phylogenetic analyses showed that the screened clones were affiliated with Gammaproteobacteria (85.7%), Thermotogales (6.8%), Epsilonproteobacteria (2.4%), low-G+C Gram-positive (2.1%), high-G+C Gram-positive, Betaproteobacteria and Nitrospira (each <1.0%). Thermopilic bacteria were found in the high-temperature water from the flooded petroleum reservoir, as well as mesophilic bacteria such as Pseudomonas-like clones. The mesophilic bacteria were probably introduced into the reservoir as it was being exploited. This work provides significant information on the structure of bacterial communities in high-temperature, long-term water-flooded petroleum reservoirs.     

Composition, spatial distribution, and diversity of the bacterial communities in the rumen of cows fed different forages

The species composition, distribution, and biodiversity of the bacterial communities in the rumen of cows fed alfalfa or triticale were investigated using 16S rRNA gene clone library analyses. The rumen bacterial community was fractionated and analyzed as three separate fractions: populations in the planktonic, loosely attached to rumen digesta particles, and tightly attached to rumen digesta particles. Six hundred and thirteen operational taxonomic units (OTUs) belonging to 32 genera, 19 families, and nine phyla of the domain Bacteria were identified from 1014 sequenced clones. Four hundred and fifty one of the 613 OTUs were identified as new species. These bacterial sequences were distributed differently among the three fractions in the rumen digesta of cows fed alfalfa or triticale. Chao 1 estimation revealed that, in both communities, the populations tightly attached to particulates were more diverse than the planktonic and those loosely attached to particulates. S-Libshuff detected significant differences in the composition between any two fractions in the rumen of cows with the same diet and between the communities fed alfalfa and triticale diets. The species richness estimated for the communities fed alfalfa and triticale is 1027 and 662, respectively. The diversity of the rumen bacterial community examined in this study is greater than previous studies have demonstrated and the differences in the community composition between two high-fiber diets have implications for sample selection for downstream metagenomics applications.     

Profiling Bacterial Diversity and Taxonomic Composition on Speleothem Surfaces in Kartchner Caverns, AZ

Caves are relatively accessible subterranean habitats ideal for the study of subsurface microbial dynamics and metabolisms under oligotrophic, non-photosynthetic conditions. A 454-pyrotag analysis of the V6 region of the 16S rRNA gene was used to systematically evaluate the bacterial diversity of ten cave surfaces within Kartchner Caverns, a limestone cave. Results showed an average of 1,994 operational taxonomic units (97 % cutoff) per speleothem and a broad taxonomic diversity that included 21 phyla and 12 candidate phyla. Comparative analysis of speleothems within a single room of the cave revealed three distinct bacterial taxonomic profiles dominated by either Actinobacteria, Proteobacteria, or Acidobacteria. A gradient in observed species richness along the sampling transect revealed that the communities with lower diversity corresponded to those dominated by Actinobacteria while the more diverse communities were those dominated by Proteobacteria. A 16S rRNA gene clone library from one of the Actinobacteria-dominated speleothems identified clones with 99 % identity to chemoautotrophs and previously characterized oligotrophs, providing insights into potential energy dynamics supporting these communities. The robust analysis conducted for this study demonstrated a rich bacterial diversity on speleothem surfaces. Further, it was shown that seemingly comparable speleothems supported divergent phylogenetic profiles suggesting that these communities are very sensitive to subtle variations in nutritional inputs and environmental factors typifying speleothem surfaces in Kartchner Caverns.     

Bacterial community composition of a shallow hypertrophic freshwater lake in China, revealed by 16S rRNA gene sequences

The phylogenetic composition of a bacterial community from a hypertrophic freshwater lake in China was investigated by sequencing cloned 16S rRNA genes. Three hundred and thirty-six bacterial clones from four clone libraries in different months (March, May, July and September in 2004) were classified into 142 operational taxonomic units, most of which were affiliated with bacterial divisions commonly found in freshwater ecosystem, e.g. Alpha-, Beta-, Gamma- and Deltaproteobacteria, Bacteriodetes and Actinobacteria. The results showed that the composition of bacterial community in the July library was the most diverse one. Actinobacteria was the most significant lineage in Lake Taihu, with dominant numbers of operational taxonomic units in the May, July and September libraries. Phylogenetic analysis suggested that 53 sequences were grouped into six novel clusters which may represent specific populations indigenous to the environment. Coverage analyses indicated that the clone libraries could provide a fine inventory of bacterial diversity in the lake.     

Bacterial diversity in biofilms formed on condenser tube surfaces in a nuclear power plant

To elucidate the bacterial diversity in biofilms formed on a condenser tube from a nuclear power plant, 16S rRNA gene sequences were examined using a PCR-cloning-sequencing approach. Twelve operational taxonomic units were retrieved in the clone library, and the estimated species richness was low (13.2). Most of the clones (94.7%) were affiliated with α-Proteobacteria; Planctomycetes and γ-Proteobacteria were much rarer. Interestingly, except for one clone belonging to Pseudoalteromonas, most of the sequences displayed sequence similarities <97% of those of the closest type strains. Based on 16S rRNA phylogenetic analysis, most bacteria were assigned to novel taxa above the species level. The low species richness and unusual bacterial composition may be attributable to selective pressure from chlorine in the cooling water. To prevent or control bacterial biofilms in cooling circuits, additional studies of the physiology and ecology of these species will be essential.     

乌梁素海富营养化湖区浮游细菌多样性及系统发育分析

水生生态系统富营养化与细菌群落之间的关系尚不明确。本文通过构建和分析16S rRNA基因片段克隆文库, 以期揭示乌梁素海富营养化水体细菌的多样性及其系统发育关系, 并探讨富营养化与细菌多样性之间的关系。利用Hae III对文库中的87个克隆子进行单酶切, 产生了23种带型, 文库覆盖度达到了73.6%, 反映出文库有较好的代表性。选择每种OTU的一个代表克隆进行测序分析, 基因序列系统发育分析结果表明, 乌梁素海中多数细菌与淡水生态系统中常见的细菌门类相同, 即α-, β-, γ-Proteobacteria, Bacteroidetes, Actinobacteria, 它们分别占总菌数的10.3%、41.4%、4.6%和6.9%, 其中β-Proteobacteria和Bacteroidetes是优势细菌类群。与典型淡水生态系统细菌群落组成不同的是, 乌梁素海中存在约10.3%的轻度嗜盐碱细菌。水体中83.9%的细菌与已培养的细菌的同源性低于97%, 其中58.9%的细菌未能鉴定到属; 其余总菌数16.1%的克隆与具有降解污染物生物活性的已知菌相近。Bacteroidetes、Firmicutes和β-Proteobacteria中的某些类群成为优势菌群可能是对乌梁素海水体富营养化的响应。     

Cultivation-independent and -dependent characterization of Bacteria resident beneath John Evans Glacier

Viable microorganisms are present in subglacial waters and sediment-laden ice beneath John Evans glacier in the Canadian high Arctic. The Bacterial communities resident in three subglacial samples were examined by amplifying 16S rRNA genes extracted from community DNA and from axenic isolates. Restriction fragment length polymorphism analysis of 341 clones produced 153 operational taxonomic units (OTUS), of which 25 dominant OTUS were sequenced. A subglacial water sample yielded Betaproteobacteria (25% of clones, particularly Comamonadaceae), Bacteroidetes (23%, particularly Flavobacterium) and Actinobacteria (14%). A second water sample had 51%Betaproteobacteria, 5%Bacteroidetes and no Actinobacteria, and a sediment sample was dominated by Betaproteobacteria (15%) and Bacteroidetes (38%). A collection of 158 morphologically distinct isolates was obtained on R2A agar using three incubation conditions: fully aerobic at 20 degrees C or 4 degrees C, or microaerobic at 20 degrees C. A total of 52 isolate OTUs were defined, comprising Bacteroidetes (predominantly Flavobacterium isolated at 4 degrees C), Betaproteobacteria (particularly Comamonadaceae), plus Actinobacteria and Alpha- and Gammaproteobacteria not detected as clones. Otherwise, the clone library and isolate collection results were quite comparable and supported earlier molecular studies at this site. Although additional undescribed diversity likely exists in these samples, combining culture-based results with molecular analysis increased the observed bacterial diversity and confirmed previous observations at this glacier and others.     

The prokaryotic community of a historically mining-impacted tropical stream sediment is as diverse as that from a pristine stream sediment

Mining negatively affects the environment by producing large quantities of metallic tailings, such as those contaminated with arsenic, with harmful consequences for human and aquatic life. A culture-independent molecular analysis was performed to assess the prokaryotic diversity and community structural changes of the tropical historically metal-contaminated Mina stream (MS) and the relatively pristine Mutuca stream (MTS) sediments. A total of 234 bacterial operational taxonomic units (OTUs) were affiliated with 14 (MS) and 17 (MTS) phyla and 53 OTUs were associated with two archaeal phyla. Although the bacterial community compositions of these sediments were markedly distinct, no significant difference in the diversity indices between the bacterial communities was observed. Additionally, the rarefaction and diversity indices indicated a higher bacterial diversity than archaeal diversity. Most of the OTUs were affiliated with the Proteobacteria and Bacteroidetes phyla. Alphaproteobacteria, Gemmatimonadetes and Actinobacteria were only found in the MS clone library. Crenarchaeal 16S rDNA sequences constituted 75 % of the MS archaeal clones, whereas Euryarchaeota were dominant in the MTS clones. Despite the markedly different characteristics of these streams, their bacterial communities harbor high diversity, suggesting that historically mining-impacted sediments promote diversity. The findings also provide basis for further investigation of members of Alphaproteobacteria as potential biological indicators of arsenic-rich sediments.     

Bacterial diversity in biofilms formed on condenser tube surfaces in a nuclear power plant

To elucidate the bacterial diversity in biofilms formed on a condenser tube from a nuclear power plant, 16S rRNA gene sequences were examined using a PCR-cloning-sequencing approach. Twelve operational taxonomic units were retrieved in the clone library, and the estimated species richness was low (13.2). Most of the clones (94.7%) were affiliated with α-Proteobacteria; Planctomycetes and γ-Proteobacteria were much rarer. Interestingly, except for one clone belonging to Pseudoalteromonas, most of the sequences displayed sequence similarities <97% of those of the closest type strains. Based on 16S rRNA phylogenetic analysis, most bacteria were assigned to novel taxa above the species level. The low species richness and unusual bacterial composition may be attributable to selective pressure from chlorine in the cooling water. To prevent or control bacterial biofilms in cooling circuits, additional studies of the physiology and ecology of these species will be essential.     

Prokaryotic diversity of a Tunisian multipond solar saltern

16S rRNA gene clone libraries were separately constructed from three ponds with different salt concentrations, M2 (15%), TS38 (25%) and S5 (32%), located within a multipond solar saltern of Sfax. The 16S rRNA genes from 216 bacterial clones and 156 archaeal clones were sequenced and phylogenetically analyzed. 44 operational taxonomic units (OTUs) were generated for Bacteria and 67 for Archaea. Phylogenetic groups within the bacterial domain were restricted to Bacteroidetes and Proteobacteria, with the exception that one cyanobacterial OTU was found in the TS38 pond. 85.7, 26.6 and 25.0% of the bacterial OTUs from M2, TS38 and S5 ponds, respectively, are novel. All archaeal 16S rRNA gene sequences were exclusively affiliated with Euryarchaeota. 75.0, 60.0 and 66.7% of the OTUs from, respectively, M2, TS38 and S5 ponds are novel. The result showed that the Tunisian multipond solar saltern harbored novel prokaryotic diversity that has never been reported before for solar salterns. In addition, diversity measurement indicated a decrease of bacterial diversity and an increase of archaeal diversity with rising salinity gradient, which was in agreement with the previous observation for thalassohaline systems. Comparative analysis showed that prokaryotic diversity of Tunisian saltern was higher than that of other salterns previously studied. A. Sghir and E. Ammar have equally contributed to this work.     

Bacterial diversity in rock varnish of extreme arid region of Turpan Basin

The bacterial community composition and diversity in rock varnish of Turpan Basin were investigated by restriction fragment length polymorphism (RFLP) and clone library of the 16S rRNA gene. 114 positive clones were screened, which could be grouped into 28 phylotypes and then further divided into 23 different operational taxonomic units (OTUs). These were affiliated into 5 phyla (Acidobacteria, Proteobacteria, Chloroflexi, Firmicutes and Cyanobacteria). Clones from actinobacteria were the dominant, accounting for 67.5% of total clones in the library, followed by Proteobacteria (15.8%), Chloroflexi (13.2%), Firmicutes (2.6%) and Cyanobacteria (0.9%). Rubrobacter (accounts for 35%) in the phylum Actinobacteria was the dominant genus and contained many species which might be resistant to gamma radiation. A 70% of the library clone sequences showed less 97% similarity to 16S rRNA gene sequences of standard strains obtained by pure culture. Shannon–Wiener index value of this study is 2.52 and is lower than deep-sea sediments, soils, lakes and other environments. Results of this study showed that bacterial diversity in rock varnishes of Turpan Basin was low, but maybe exist a large number of new unknown taxons, especially species that could well adapted to drought and resist radiation.     

Diversity within cyanobacterial mat communities in variable salinity meltwater ponds of McMurdo Ice Shelf, Antarctica

This study investigated the diversity of cyanobacterial mat communities of three meltwater ponds--Fresh, Orange and Salt Ponds, south of Bratina Island, McMurdo Ice Shelf, Antarctica. A combined morphological and genetic approach using clone libraries was used to investigate the influence of salinity on cyanobacterial diversity within these ecosystems without prior cultivation or isolation of cyanobacteria. We were able to identify 22 phylotypes belonging to Phormidium sp., Oscillatoria sp. and Lyngbya sp. In addition, we identified Antarctic Nostoc sp., Nodularia sp. and Anabaena sp. from the clone libraries. Fresh (17 phylotypes) and Orange (nine phylotypes) Ponds showed a similar diversity in contrast to that of the hypersaline Salt Pond (five phylotypes), where the diversity within cyanobacterial mats was reduced. Using the comparison of identified phylotypes with existing Antarctic sequence data, it was possible to gain further insight into the different levels of distribution of phylotypes identified in the investigated cyanobacterial mat communities of McMurdo Ice Shelf.     

Comparison of the Cecal Microbiota of Domestic and Wild Turkeys

The extent to which production methods alter intestinal microbial communities of livestock is currently unknown. As the intestinal microbiota may affect animal health, nutrition, and food safety, a baseline comparison of the cecal communities of domestic and wild turkeys was performed. Oligonucleotide fingerprinting of ribosomal RNA (rRNA) genes (OFRG) of 2,990 16S rRNA clones and dot blot quantification of dominant populations were used to identify the dominant bacterial taxa. Seventy-three percent of all the clones belonged to as yet uncultured genera. However, at a higher phylogenetic level, the OFRG library was composed of 54% Bacteroidetes clones (52% of the domestic library clones, 56% of the wild library clones), 30% Firmicutes clones (33% of the domestic library clones, 32% of the wild library clones), 3% Proteobacteria clones (5% domestic, 2% wild), and 3% Deferribacteres clones (4% domestic, 1% wild). Seven percent of the clones were unidentifiable (6% domestic, 9% wild). Bacteroidetes clones included the genera Alistipes, Prevotella, Megamonas, and Bacteroides. Of the Clostridiales clones, groups IV, IX, and XIV including genera Faecalibacterium, Megasphaera, Phascolarctobacterium, and Papillibacter were predominant. Lactobacillus, Enterococcus, and Streptococcus bacilli were also identified. beta- delta- and gamma-proteobacterial genera included Acinetobacter, Sutterella, and Escherichia. Deferribacteres clones showed high similarity to Mucispirillum schaedleri. Statistical comparison of the domestic and wild turkey clone libraries indicated similar levels of community richness and evenness despite the fact that the two libraries shared only 30% of the total clone operational taxonomic units. Together these results indicate that although high level taxonomic community structure is similar, high-density turkey production causes considerable divergence of the genera found in the ceca of commercial birds from those of their wild counterparts.     

Development of a Bacterial Cell Enrichment Method and its Application to the Community Analysis in Soybean Stems

A method was developed for enriching bacterial cells from soybean stems which was recalcitrant for a culture-independent analysis of bacterial community due to the interference with plant DNA. Stem homogenates were fractionated by a series of differential centrifugations followed by a Nycodenz density gradient centrifugation. The efficiency of bacterial cell enrichment was assessed by ribosomal intergenic spacer analysis (RISA). The intensity and the number of bacterial amplicons of RISA were markedly increased in the DNA extracted from the enriched bacterial cells compared to that in the DNA directly extracted from soybean stems. The phylogenetic diversity of the enriched bacterial cells was evaluated by analyzing a clone library of 16S rRNA gene in comparison with those of the culturable fractions of the enriched and non-enriched stem-associated bacteria, endophytic bacteria, and epiphytic bacteria. The results indicated that the method was able to enrich both endophytic and epiphytic bacteria from soybean stems, and was useful to assess the bacterial diversity based on a 16S rRNA gene clone library. When the sequence data from all clones (1,332 sequences) were combined, 72 operational taxonomic units were affiliated with Proteobacteria (Alpha-, Beta-, and Gammaproteobacteria), Actinobacteria, Firmicutes, and Bacteroidetes, which also provided the most comprehensive set of data on the bacterial diversity in the aerial parts of soybeans.     

Life in extreme environments: microbial diversity in Great Salt Lake,Utah

Great Salt Lake (GSL) represents one of the world’s most hypersaline environments. In this study, the archaeal and bacterial communities at the North and South arms of the lake were surveyed by cloning and sequencing the 16S rRNA gene. The sampling locations were chosen for high salt concentration and the presence of unique environmental gradients, such as petroleum seeps and high sulfur content. Molecular techniques have not been systematically applied to this extreme environment, and thus the composition and the genetic diversity of microbial communities at GSL remain mostly unknown. This study led to the identification of 58 archaeal and 42 bacterial operational taxonomic units. Our phylogenetic and statistical analyses displayed a high biodiversity of the microbial communities in this environment. In this survey, we also showed that the majority of the 16S rRNA gene sequences within the clone library were distantly related to previously described environmental halophilic archaeal and bacterial taxa and represent novel phylotypes.