Hypersaline Soils Research Articles

Ferric Sulfate and Proline Enhance Heavy-Metal Tolerance of Halophilic/Halotolerant Soil Microorganisms and Their Bioremediation Potential for Spilled-Oil Under Multiple Stresses.

The aim of this study was to explore the heavy-metal resistance and hydrocarbonoclastic potential of microorganisms in a hypersaline soil. For this, hydrocarbonoclastic microorganisms were counted on a mineral medium with oil vapor as a sole carbon source in the presence of increasing concentrations of ZnSO4, HgCl2, CdSO4, PbNO3, CuSO4, and Na2HAsO4. The colony-forming units counted decreased in number from about 150 g-1 on the heavy-metal-free medium to zero units on media with 40–100 mg l-1 of HgCl2, CdSO4, PbNO3, or Na2HAsO4. On media with CuSO4 or ZnSO4 on the other hand, numbers increased first reaching maxima on media with 50 mg l-1 CuSO4 and 90 mg l-1 ZnSO4. Higher concentrations reduced the numbers, which however, still remained considerable. Pure microbial isolates in cultures tolerated 200–1600 mg l-1 of HgCl2, CdSO4, PbNO3, CuSO4, and Na2HAsO4 in the absence of crude oil. In the presence of oil vapor, the isolates tolerated much lower concentrations of the heavy metals, only 10–80 mg l-1. The addition of 10 Fe2(SO4)3 and 200 mg l-1 proline (by up to two- to threefold) enhanced the tolerance of several isolates to heavy metals, and consequently their potential for oil biodegradation in their presence. The results are useful in designing bioremediation technologies for oil spilled in hypersaline areas.

Characterizing the new bacterial isolates of high yielding exopolysaccharides under hypersaline conditions

Abstract The ability of plant growth promoting bacteria (PGPR) to survive under salinity stress has important implications on the growth of their host plants. The production of different biochemicals by the bacteria including exopolysaccharides (EPS) may determine their survival as well as their alleviating effects under stress. However, one important approach, which deserves more attention, is the performance of PGPR under stressed conditions such as hypersaline conditions. Accordingly, the objectives of this study were: 1) the isolation and characterization of new bacterial isolates of high yielding EPS from a hypersaline soil, and 2) the investigation of EPS structure in the presence of salt. Samples of soil were spread on nutrient agar ± %5 NaCl to determine the salt tolerant colonies with the maximum tolerable salt concentrations (MTC). Among the isolates of “salt tolerant bacteria” (STB), six isolates had the potential to produce EPS. According to 16S rDNA gene sequencing, three salt tolerant EPS-producing isolates were identified as Bacillus aerius ATHM35, Arthrobacter luteolus ATHM 36, and Halomonas eurihalina ATHM 37. It is the first time that Bacillus aerius and Arthrobacter luteolus have been isolated from hypersaline soils. The biochemical analyses indicated that the isolates were able to produce a wide range of products including enzymes such as urease, lactose, oxidase and catalase. With increasing salt concentration the production of EPS by the isolates significantly (P

Metagenome Sequencing of Prokaryotic Microbiota from Two Hypersaline Soils of the Odiel Salt Marshes in Huelva, Southwestern Spain.

ABSTRACTTwo 454 shotgun metagenomes were sequenced from hypersaline soil samples collected in the Odiel salt marsh area in Huelva, southwestern Spain. Analysis of contigs and 16S rRNA-related sequences showed that Halobacteria, Balneolaeota, and Bacteroidetes were the dominant groups. Rhodothermaeota and Nanohaloarchaeota were also abundant.

Draft Genome Sequence of Glycomyces fuscus TRM 49117, Isolated from a Hypersaline Soil Sample.

ABSTRACTGlycomyces spp. are rare actinomycetes that are potential antibiotic producers. Here, we report the draft genome sequence of Glycomyces fuscus TRM 49117. This is the first genome report of a bacterium belonging to the genus Glycomyces. The genome information of G. fuscus will contribute to studies on the structure and function of antibiotics.

Corrigendum to ″Schmidingerothrix salinarum nov. spec. isthe Molecular Sister of the Large Oxytrichid Clade (Ciliophora, Hypotricha) by Foissner et al. 2014″.

Journal of Eukaryotic MicrobiologyVolume 65, Issue 2 p. 290-290 CorrigendumFree Access Corrigendum to ″Schmidingerothrix salinarum nov. spec. is the Molecular Sister of the Large Oxytrichid Clade (Ciliophora, Hypotricha) by Foissner et al. 2014″ This article corrects the following: Schmidingerothrix salinarum nov. spec. is the Molecular Sister of the Large Oxytrichid Clade (Ciliophora, Hypotricha) Wilhelm Foissner, Sabine Filker, Thorsten Stoeck, Volume 61Issue 1Journal of Eukaryotic Microbiology pages: 61-74 First Published online: December 10, 2013 First published: 20 November 2017 https://doi.org/10.1111/jeu.12481AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat In the article: Foissner, W., Filker, S., and Stoeck T. 2014. Schmidingerothrix salinarum nov. spec. is the Molecular Sister of the Large Oxytrichid Clade (Ciliophora, Hypotricha). J. Eukaryot. Microbiol., 61(1): 61–74. https://doi.org/10.1111/jeu.12087, the ZooBank registration number was omitted. Foissner et al. (2014) described the morphology, ontogeny, and phylogeny of a new Schmidingerothrix species in this electronic-only journal. Since the electronic article does not contain ZooBank registration, it is not published (available) with respect to the International Code of Zoological Nomenclature (ICZN 1999, 2012, Articles 8.5, 9.11). However, such work likely remains available as source for further purposes, similar to a suppressed work (ICZN 1999, Article 8.7.1). To become available, Schmidingerothrix salinarum must be registered in ZooBank (ICZN 2012). ZooBank registration http://zoobank.org/urn:lsid:zoobank.org:pub:33751519-8DAB-42CD-814E-C72926D5E39F Schmidingerothrix salinarum nov. spec. (Table 2 and Fig. 1A–L, 2A–M, 3A–D, 4A–H, 5, 6A–F, 7A–I, 8A–D in Foissner et al. 2014) Diagnosis (from Foissner et al. 2014, p. 73). Size in vivo about 95 × 17 μm. Body slender (~5.5:1), usually widest in mid-portion, with short but distinct tail. Four macronuclear nodules, forming a series near right margin of cell; zero to two micronuclei. Cortical granules in loose rows, colorless, about 1 μm across. Three frontal cirri and three frontoventral cirral rows. Frontal cirrus 1 subapical close to ventral part of adoral zone of membranelles. Frontoventral row 1 composed of an average of four cirri; row 2 of 18 cirri; row 3 of five cirri. Right marginal row composed of an average of 23 cirri, left of 17. Adoral zone about 32% of body length, composed of an average of three frontal and 21 ventral membranelles. Endoral membrane 12 μm long on average. Type locality. Solar saltern in the Ria Formosa National Park near to the town of Faro, Portugal, W7°57′41.0684″, N37°00′29.4851″. Type material. The holotype slide and two paratype slides with protargol-impregnated specimens and two paratype slides with hematoxylin-stained cells have been deposited in the Biologiezentrum of the Oberösterreichische Landesmuseum in Linz (LI), Austria, reg. no. 2013/33–37. Relevant specimens have been marked by black ink circles on the coverslip. Etymology. See same section in Foissner et al. (2014, p. 74). Morphology of Schmidingerothrix salinarum nov. spec. See same section in Foissner et al. (2014, p. 63, Table 2, and Fig. 1A–L, 2A–M, 3A–D, 4A–H). Molecular phylogeny. See same section in Foissner et al. (2014). GenBank accession number. KC991098 (SSU rDNA; length 1,769 bp; GC content 45.11%). Ontogenesis of Schmidingerothrix salinarum nov. spec. See same section in Foissner et al. (2014, p. 67 and Fig. 6A–F, 7A–H, 8A–D). Discussion. For comparison of Schmidingerothrix salinarum Foissner et al., 2017 with S. extraordinaria Foissner, 2012, type of the genus, see same section in Foissner et al. (2014, p. 72). Remarks: In future, this species has to be cited as “Schmidingerothrix salinarum Foissner, Filker & Stoeck, 2017” (for justification, see introduction). Literature Cited Foissner, W. 2012. Schmidingerothrix extraordinaria nov. gen., nov. spec., a secondarily oligomerized hypotrich (Ciliophora, Hypotricha, Schmidingerotrichidae nov. fam.) from hypersaline soils of Africa. Eur. J. Protistol., 48: 237– 251. Foissner, W., Filker, S. & Stoeck, T. 2014. Schmidingerothrix salinarum nov. spec. is the molecular sister of the large oxytrichid clade (Ciliophora, Hypotricha). J. Eukaryot. Microbiol., 61: 61– 74. ICZN (International Commission on Zoological Nomenclature) 1999. International Code of Zoological Nomenclature. International Trust for Zoological Nomenclature, London, 306 p. ICZN (International Commission of Zoological Nomenclature) 2012. Amendment of Articles 8, 9, 10, 21 and 78 of the International Code of Zoological Nomenclature to expand and refine methods of publication. Bull. Zool. Nom., 69: 161– 169. Volume65, Issue2March/April 2018Pages 290-290 ReferencesRelatedInformation

HqiA, a novel quorum-quenching enzyme which expands the AHL lactonase family

The screening of a metagenomic library of 250,000 clones generated from a hypersaline soil (Spain) allowed us to identify a single positive clone which confers the ability to degrade N-acyl homoserine lactones (AHLs). The sequencing of the fosmid revealed a 42,318 bp environmental insert characterized by 46 ORFs. The subcloning of these ORFs demonstrated that a single gene (hqiA) allowed AHL degradation. Enzymatic analysis using purified HqiA and HPLC/MS revealed that this protein has lactonase activity on a broad range of AHLs. The introduction of hqiA in the plant pathogen Pectobacterium carotovorum efficiently interfered with both the synthesis of AHLs and quorum-sensing regulated functions, such as swarming motility and the production of maceration enzymes. Bioinformatic analyses highlighted that HqiA showed no sequence homology with the known prototypic AHL lactonases or acylases, thus expanding the AHL-degrading enzymes with a new family related to the cysteine hydrolase (CHase) group. The complete sequence analysis of the fosmid showed that 31 ORFs out of the 46 identified were related to Deltaproteobacteria, whilst many intercalated ORFs presented high homology with other taxa. In this sense, hqiA appeared to be assigned to the Hyphomonas genus (Alphaproteobacteria), suggesting that horizontal gene transfer had occurred.

Biostimulation of indigenous microorganisms for bioremediation of oily hypersaline microcosms from the Arabian Gulf Kuwaiti coasts

Hypersaline soil and water samples were collected in summer and winter from the “sabkha” area at the Kuwaiti shore of the Arabian Gulf. Physicochemical parameters were analyzed, and found suitable for microbial oil-removal. Summer- and winter-microcosms were treated with individual cation (K+, Ca2+, Mg2+, Fe3+) salts, and with animal blood and commercial yeast, as cost-effective vitamin sources. Those microcosms were exposed to the open environment for six winter and six summer months, and analyzed for their hydrocarbonoclastic microorganisms at time zero and in two month intervals. The hydrocarbonoclastic microbial communities in the microcosms consisted of halophilic bacteria and haloarchaea. The constituent bacterial species varied according to the season. Three species, Dietzia kunjamensis, Marinobacter lacisalsi and Halomonas oxialensis consistently occurred both in summer- and winter-samples, but the remaining species were different. On the other hand, the haloarchaeal communities in summer and winter were quite similar, and consisted mainly of Haloferax spp and Halobacterium spp. Treating the microcosms with cations and with vitamin-containing natural products enhanced microbial numbers and oil-removal. The effectiveness of the cations in oil-removal was in the order; Fe3+ (94%) > Ca2+ (89%) > Mg2+ (85%) > K+ (82%). Thus, oily microcosms amended with trivalent and divalent cations lost most of the oil, and those amended with commercial yeast and with animal blood, as vitamin sources, lost 78% and 72% oil, respectively.

Draft Genome Sequence of Halolamina pelagica CDK2 Isolated from Natural Salterns from Rann of Kutch, Gujarat, India.

ABSTRACTHalolamina pelagica strain CDK2, a halophilic archaeon (growth range 1.36 to 5.12 M NaCl), was isolated from rhizosphere of wild grasses of hypersaline soil of the Rann of Kutch, Gujarat, India. Its draft genome contains 2,972,542 bp and 3,485 coding sequences, depicting genes for halophilic serine proteases and trehalose synthesis.

Characterization of basidiomycetous yeasts in hypersaline soils of the Urmia Lake National Park, Iran.

Urmia Lake, located in northwest Iran, is an oligotrophic and extremely hypersaline habitat that supports diverse forms of life. Owing to its unique biodiversity and special environmental conditions, Urmia Lake National Park has been designated as one of the biosphere reserves by UNESCO. This study was aimed to characterize basidiomycetous yeasts in hypersaline soils surrounding the Urmia Lake National Park using a polyphasic combination of molecular and physiological data. Soil samples were collected from eight sites in Lake Basin and six islands insides the lake. Yeast strains were identified by sequencing the D1/D2 domains of the 26S rRNA gene. When D1/D2 domain sequencing did not resolve the identity of the species, strain identification was obtained by ITS 1 & 2 sequencing. Twenty-one species belonging to the genera Cystobasidium, Holtermanniella, Naganishia, Rhodotorula, Saitozyma, Solicoccozyma, Tausonia, Vanrija, and Vishniacozyma were identified. Solicoccozyma aeria represented the dominant species. The ability of isolates to grow at 10 and 15% of NaCl was checked; about two-thirds of the strains grew at 10%, while about 13% of the isolates grew in medium with 15% NaCl. this study is the first study on the culturable yeast diversity in hypersaline soils surrounding an Asian lake.

Two novel Aspergillus species from hypersaline soils of The National Park of Lake Urmia, Iran

Two novel Aspergillus species, one belonging to the section Terrei and the other to section Flavipedes, were isolated from hypersaline soils of The National Park of Lake Urmia (Iran) and are here described as Aspergillus iranicus and Aspergillus urmiensis. A polyphasic taxonomic approach comprising extrolite profiles, phenotypic characters and molecular data (beta-tubulin, calmodulin and ribosomal polymerase II second largest subunit gene sequences) was applied to determine their novel taxonomic status. Aspergillus iranicus (CBS 139561T) is phylogenetically related to A. carneus, A. niveus, A. allahabadii and A. neoindicus, and it can be differentiated from those species by a unique extrolite pattern (citrinin, gregatins, and a terrequinone) and its conidial colour. Aspergillus urmiensis (CBS 139558T) shares a most recent common ancestor with A. templicola. The former species produces globose vesicles, and those of A. templicola are predominantly elongate. The Aspergillus urmiensis isolates produce several uncharacterized extrolites. Two other strains obtained during this study reside in a clade, together with the type strain of A. movilensis (CCF 4410T), and are identified accordingly. Based on the phylogenetic data presented in this study, A. frequens is reduced to synonymy with A. micronesiensis and A. mangaliensis is considered to be a synonym of A. templicola.

Tracking tidal inundation in a coastal salt marsh with Helikite airphotos: Influence of hydrology on ecological zonation at Crab Haul Creek, South Carolina

Abstract Ecological zones in a salt marsh are influenced by many factors, including hydroperiod, soil salinity, groundwater flow, and nutrient/oxygen availability. In this project, high-resolution aerial images taken by a Helikite helium balloon-kite at 100 m altitude were used to develop a detailed flooding model and derive a spatially comprehensive map of ecological zones at the headwaters of a small tidal marsh creek at a forest-marsh boundary in North Inlet estuary, South Carolina. We constructed photomosaics from Helikite imagery over a 150 × 100 m area to identify ecological zones using an automated, maximum likelihood classification. In the same area, we developed a digital terrain model with ± 2 cm overall vertical accuracy, primarily from waterlines at known tide height tracked by Helikite imagery and GPS. These are low-cost, easily implemented methods for studying marsh processes where access is often challenging. Quantifying frequency of inundation, an approximation of hydroperiod, using our terrain model and comparing it to ecological zones revealed that there is not a linear relationship between elevation and inundation above mean high tide. Ecological zones exhibit complex spatial patterns that neither elevation nor hydroperiod alone can explain. In the northwestern basin, adjacent to a forest-marsh boundary, inflow of low salinity groundwater from a large freshwater lens beneath the forest prevents the development of Salicornia virginica zones and allows the high-marsh plant Juncus roemarianus to be present at middle-to-low marsh elevations. Conversely, in the southwestern portion of the basin adjacent to a relict beach ridge underlain by a smaller freshwater lens, saltwater infiltration during spring tides and evapotranspiration during neap tides allows Salicornia virginica zones to develop in hypersaline soils. Many of the current numerical models for predicting salt marsh ecological zonation consider hydroperiod as the main factor; however, the asymmetry of the basin in both ecological zones and freshened groundwater discharge imply groundwater and surface-water inundation should both be considered in the distribution of ecological zones in a coastal salt marsh.

Rice straw addition does not substantially alter microbial properties under hypersaline soil conditions

As a consequence of climate change, a rising sea level results in increased saltwater intrusion and soil salinity problems in Bangladesh. The affected agricultural soils are characterized by temporarily high concentrations of soluble salts, low organic matter and reduced plant growth. Addition of organic matter can reduce the negative effects of salinity on soil microorganisms and positively influence nutrient cycling. Therefore, the benefit of rice straw addition to saline paddy soils on the microbial community and associated mineralization dynamics was investigated in a short-term aerobic laboratory incubation experiment. Soil samples were collected from two locations in the coastal area of Bangladesh previously prone to salinity. Both soils were incubated with rice straw (0, 25 and 50 % of the straw yield) and three levels of salinity (addition of 0, 15 and 50 mg NaCl g−1 soil) for 28 days at 22 °C. Soil respiration was measured during incubation, and microbial properties, extractable C and inorganic N were determined at the end of the experiment. Increasing soil salinity only slightly decreased soil respiration and the ergosterol content, whereas the microbial biomass C was not consistently affected by increasing salinity and was generally at a very low level. Moreover, the bacterial-to-fungal abundance ratio increased with increasing salinity. Nitrification was only substantially reduced at extremely high salinity, indicating adaptation of the nitrifiers. On the other hand, addition of rice straw only slightly improved microbial properties and resulted in N immobilization. To improve soil fertility, addition of organic matter is crucial. Returning a portion of the rice straw to the soil only slightly contributes to this goal. Moreover, rice straw is a valuable resource used, e.g. as feed or burning material, making the return to the field a less economically viable option. Other sources of larger quantities and higher quality of organic matter should thus be preferred.

Isolation and characterization of extremely halophilic CO-oxidizing Euryarchaeota from hypersaline cinders, sediments and soils and description of a novel CO oxidizer, Haloferax namakaokahaiae Mke2.3T, sp. nov.

The phylogenetic affiliations of organisms responsible for aerobic CO oxidation in hypersaline soils and sediments were assessed using media containing 3.8 M NaCl. CO-oxidizing strains of the euryarchaeotes, Haloarcula, Halorubrum, Haloterrigena and Natronorubrum, were isolated from the Bonneville Salt Flats (UT) and Atacama Desert salterns (Chile). A halophilic euryarchaeote, Haloferax strain Mke2.3(T), was isolated from Hawai'i Island saline cinders. Haloferax strain Mke2.3(T) was most closely related to Haloferax larsenii JCM 13917(T) (97.0% 16S rRNA sequence identity). It grew with a limited range of substrates, and oxidized CO at a headspace concentration of 0.1%. However, it did not grow with CO as a sole carbon and energy source. Its ability to oxidize CO, its polar lipid composition, substrate utilization and numerous other traits distinguished it from H. larsenii JCM 13917(T), and supported designation of the novel isolate as Haloferax namakaokahaiae Mke2.3(T), sp. nov (= DSM 29988, = LMG 29162). CO oxidation was also documented for 'Natronorubrum thiooxidans' HG1 (Sorokin, Tourova and Muyzer 2005), N. bangense (Xu, Zhou and Tian 1999) and N. sulfidifaciens AD2(T) (Cui etal. 2007). Collectively, these results established a previously unsuspected capacity for extremely halophilic aerobic CO oxidation, and indicated that the trait might be widespread among the Halobacteriaceae, and occur in a wide range of hypersaline habitats.

Draft Genome Sequence of Streptomyces mutabilis TRM45540, Isolated from a Hypersaline Soil Sample.

We report here the draft genome sequence of Streptomyces mutabilis TRM45540, a strain isolated from a soil sample from Xinjiang, China. Analysis of the genome using the bioinformatics tool antiSMASH showed the presence of many unique natural-product biosynthetic pathways.

Microbiota studies in the bile duct strongly suggest a role for Helicobacter pylori in extrahepatic cholangiocarcinoma

Biliary tract cancer or extrahepatic cholangiocarcinoma (ECCA) represents the sixth commonest cause of cancer in the gastrointestinal tract in western countries. We aimed to characterize the microbiota and its predicted associated functions in the biliary tract of ECCA and benign biliary pathology (BBP). Samples were taken from 100 patients with ECCA and 100 patients with BBP by endoscopic cholangio-pancreatography for DNA extraction. Ten patients with ECCA and ten with BBP were selected for microbiota studies using the V4-16S rRNA gene and sequenced in Illumina platform. Microbiota analyses included sample-to-sample distance metrics, ordination/clustering and prediction of functions. Presence of Nesterenkonia sp. and Helicobacter pylori cagA and vacA genes were tested in the 100 ECCA and 100 BBP samples. Phylum Proteobacteria dominated all samples (60.4% average). Ordination multicomponent analyses showed significant microbiota separation between ECCA and BBP (p 0.010). Analyses of 4002 operational taxonomic units with presence variation in at least one category probed a separation of ECCA from BBP. Among these, Nesterenkonia decreased, whereas Methylophilaceae, Fusobacterium, Prevotella, Actinomyces, Novosphingobium and H. pylori increased in ECCA. Predicted associated functions showed increased abundance of H. pylori virulence genes in ECCA. cagA and vacA genes were confirmed by PCR in ECCA and BBP samples. This is the first microbiota report in ECCA and BBP to show significant changes in microbial composition. Bacterial species unusual for human flora were found: Methylophilaceae and Nesterenkonia are reported in hypersaline soils, and Mesorhizobium is a nitrogen-fixing bacterium. Enrichment of virulence genes confirms previous studies suggesting that H. pylori might be associated with ECCA.

Paraglycomyces xinjiangensis gen. nov., sp. nov., a halophilic actinomycete.

A novel halophilic actinobacterium, designated strain TRM 49201T, was isolated from a hypersaline soil in Xinjiang Province, north-west China. The strain was aerobic, Gram-stain-positive and halophilic. The aerial mycelium was chaotic with irregular branches, and spherical sporangia containing several spherical spores developed at mycelial aggregations. The strain had an optimum NaCl concentration for growth of 8-13 % (w/v). The whole-cell sugar pattern of strain TRM 49201T consisted of xylose and ribose. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-10(H2). The polar lipids were diphosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, phosphatidylglycerol, phosphatidylcholine and four unknown phospholipids. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 70 mol%. Phylogenetic analysis showed that strain TRM 49201T can be distinguished from representatives of Glycomyces, Stackebrandtia and Haloglycomyces, the three existing genera in the family Glycomycetaceae, based on low 16S rRNA gene sequence similarities ( < 94.42 %). Strain TRM 49201T is thus considered to represent a novel species of a new genus in the family Glycomycetaceae, for which the name Paraglycomyces xinjiangensis gen. nov., sp. nov. is proposed. The type strain of Paraglycomyces xinjiangensis is TRM 49201T ( = NRRL B-24926T = CCTCC AA 2013002T = KACC 17683T).

Haloarchaea Endowed with Phosphorus Solubilization Attribute Implicated in Phosphorus Cycle.

Archaea are unique microorganisms that are present in ecological niches of high temperature, pH and salinity. A total of 157 archaea were obtained from thirteen sediment, water and rhizospheric soil samples collected from Rann of Kutch, Gujarat, India. With an aim to screen phosphate solubilizing archaea, a new medium was designed as Haloarchaea P Solubilization (HPS) medium. The medium supported the growth and P solubilization activity of archaea. Employing the HPS medium, twenty isolates showed the P-solubilization. Phosphate solubilizing archaea were identified as seventeen distinct species of eleven genera namely Haloarcula, Halobacterium, Halococcus, Haloferax, Halolamina, Halosarcina, Halostagnicola, Haloterrigena, Natrialba, Natrinema and Natronoarchaeum. Natrinema sp. strain IARI-WRAB2 was identified as the most efficient P-solubilizer (134.61 mg/L) followed by Halococcus hamelinensis strain IARI-SNS2 (112.56 mg/L). HPLC analysis detected seven different kinds of organic acids, namely: gluconic acid, citric acid, formic acid, fumaric acid succinic acid, propionic acid and tartaric acid from the cultures of these isolates. These phosphate solubilizing halophilic archaea may play a role in P nutrition to vegetation growing in these hypersaline soils. This is the first report for these haloarchaea to solubilize considerable amount of P by production of organic acids and lowering of pH.

Two fixed ratio dilutions for soil salinity monitoring in hypersaline wetlands.

Highly soluble salts are undesirable in agriculture because they reduce yields or the quality of most cash crops and can leak to surface or sub-surface waters. In some cases salinity can be associated with unique history, rarity, or special habitats protected by environmental laws. Yet in considering the measurement of soil salinity for long-term monitoring purposes, adequate methods are required. Both saturated paste extracts, intended for agriculture, and direct surface and/or porewater salinity measurement, used in inundated wetlands, are unsuited for hypersaline wetlands that often are only occasionally inundated. For these cases, we propose the use of 1:5 soil/water (weight/weight) extracts as the standard for expressing the electrical conductivity (EC) of such soils and for further salt determinations. We also propose checking for ion-pairing with a 1:10 or more diluted extract in hypersaline soils. As an illustration, we apply the two-dilutions approach to a set of 359 soil samples from saline wetlands ranging in ECe from 2.3 dS m-1 to 183.0 dS m-1. This easy procedure will be useful in survey campaigns and in the monitoring of soil salt content.

Spatial microbial community structure and biodiversity analysis in “extreme” hypersaline soils of a semiarid Mediterranean area

In recent years specific attention has been paid on the biotechnological potential of microorganisms in extreme soils, in particular in saline soils. Salinity is one of the most widespread soil degradation processes on the Earth, and saline soils can be defined as extreme soils or border line habitats in which several factors, as high salt content, may limit the growth of organisms. In this study, the physical, chemical and microbiological soil properties were investigated in the shallower horizon of natural salt-affected soils in Sicily (Italy). The main aim of the research was to evaluate the structure and diversity of bacterial and archaeal communities by terminal-restriction fragment length polymorphism (T-RFLP) according to arbitrary different classes of vegetation and salt crust cover in soils. Furthermore, the structure of microbial communities was assessed considering the heterogeneity of physical–chemical properties of the habitat under investigation, as a function of vegetation, crust cover, and salinity classes. The results provided information on the type of distribution of different microbial community composition and diversity as a function of both vegetation and crust cover as well as salinity classes. In particular, the archaeal community showed a richness and diversity significantly affected by the spatial gradients of soil salinity, conversely, the bacterial one showed a decreasing trend with increasing gradient of soil salinity. The T-RFLP cluster analysis showed the formation of two groups for both bacterial and archaeal community, significantly (p<0.05) influenced by sand and silt content, electrical conductivity (ECe), vegetation cover percentage, salt crust and for by texture composition. In particular, the discriminant analysis obtained for the different salt crust classes for archaeal community stressed the membership of one of the two clusters to the class with the lower salt crust percentage (0–40%).

Archaeal Communities in a Heterogeneous Hypersaline-Alkaline Soil.

In this study the archaeal communities in extreme saline-alkaline soils of the former lake Texcoco, Mexico, with electrolytic conductivities (EC) ranging from 0.7 to 157.2 dS/m and pH from 8.5 to 10.5 were explored. Archaeal communities in the 0.7 dS/m pH 8.5 soil had the lowest alpha diversity values and were dominated by a limited number of phylotypes belonging to the mesophilic Candidatus Nitrososphaera. Diversity and species richness were higher in the soils with EC between 9.0 and 157.2 dS/m. The majority of OTUs detected in the hypersaline soil were members of the Halobacteriaceae family. Novel phylogenetic branches in the Halobacteriales class were detected in the soil, and more abundantly in soil with the higher pH (10.5), indicating that unknown and uncharacterized Archaea can be found in this soil. Thirteen different genera of the Halobacteriaceae family were identified and were distributed differently between the soils. Halobiforma, Halostagnicola, Haloterrigena, and Natronomonas were found in all soil samples. Methanogenic archaea were found only in soil with pH between 10.0 and 10.3. Retrieved methanogenic archaea belonged to the Methanosarcinales and Methanomicrobiales orders. The comparison of the archaeal community structures considering phylogenetic information (UniFrac distances) clearly clustered the communities by pH.