Saline Soil Samples Research Articles

Halostreptopolyspora alba gen. nov., sp. nov., a halophilic actinobacterium isolated from saline soil of Xinjiang, Northwest of China.

A Gram-stain-positive, aerobic, moderate halophilic actinobacterium, designated strain YIM 96095T, was isolated from a saline soil sample collected from Aiding Lake, Xinjiang, North-western China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate belonged to the family Nocardiopsidaceae, formed a distinct subclade, and was most closely related to Lipingzhangella halophila DSM 102030T and Allosalinactinospora lopnorensis DSM 45697T with sequence identity values of 95.8 and 95.1%, respectively. Optimal growth occurred at 37 °C, pH 7.0-8.0 and with 5-16% (w/v) NaCl, with well-developed, non-fragmented substrate mycelia and single-, double-, or triple-wrinkled spore(s) on the mature aerial hyphae. The chemical analysis presented meso-diaminopimelic acid as the diagnostic diamino acid of the cell-wall peptidoglycan, and glucose, galactose and rhamnose as the major whole-cell sugars, and iso-C15 : 0 and anteiso-C15 : 0 as the major fatty acids. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, unidentified phospholipids and unidentified glycolipid. The menaquinones were MK-10(H8), MK-10(H6) and MK-9(H10). Its G+C content was 69.7 mol% in the determined genome sequence. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, a novel genus and species named Halostreptopolyspora alba gen. nov., sp. nov. is proposed for isolate YIM 96095T (=KCTC 49266T=CGMCC 4.7636T).

Dissolution of clotted blood from slaughtered cattle by alkaline protease produced by Streptomyces violaceoruber isolated from saline soil in Saudi Arabia

Saudi Arabia suffers from the spread of diseases linked to clotted blood leaking from slaughtered livestock. Anticoagulant proteases produced by Streptomyces are used to safely dissolve clotted blood. Halophilic Streptomyces isolates were extracted from saline soil in Saudi Arabia and tested to dissolve clotted blood by protease. The most protease-producing isolate was identified using classical and genetic methods. The protease was precipitated with saturated ammonium sulfate from a batch of blood clots inoculated with the most protease-producing isolates. Streptomyces isolates (410) were recovered from thirty saline soil samples collected from Dammam (170 isolates, 41.4 %), Al-Khobar (126 isolates, 30.8 %) and Al-Ahsa (114 isolates, 27.8 %). Proteolytic activity was observed in 305 isolates including the most protease-producing isolate S295, which showed the highest activity (33.8 mm), and was identified as S. violaceoruber (99 % similarity). Among all isolates, 241 showed partial hemolysis (alpha) and 64 showed complete hemolysis (beta), including isolate S295 that presented the highest hemolytic activity (0.58 %). The alkaline protease was precipitated with saturated ammonium sulfate (60 %), and it was found that its activity was 5.2 U/ml, total activity 24,960 U/ml, specific activity 463 U/mg, purification fold 15.2 and yield 78 %. The purified alkaline protease was electrophoresed as a single band at 45 kDa.

Production and Optimization of Extracellular α-amylase From Halophilic Bacteria Cytobacillus oceanisediminis Isolated From Wadi-El-Natrun, Egypt

The current study aimed to maximize α-amylase enzyme production by halophilic bacteria Cytobacillus oceanisediminis isolated from soil of Wadi-El-Natrun, Egypt. The results showed that of 21 halophilic bacterial isolates recovered from saline soil samples, eight isolates were high amylase producers. Interestingly, the bacterial isolate AHB6 exhibited the highest extracellular amylase production and was selected for further studies. This isolate was molecularly identified based on the 16srRNA gene sequencing as Cytobacillus oceanisediminis and has the accession number OM759999. The optimum temperature for α-amylase enzyme was 45 °C and exhibited thermostability at 45 °C for 1 h and retained more than 80% of its original activity. The α-amylase enzyme was active in almost all tested pHs and reached its highest activity at pH 9. Also, the optimum culture conditions for α-amylase enzyme production were wheat bran as carbon source, 2 g/l K2HPO4 as potassium source, 6 g/l MgSO4 as magnesium source and 0.5 g/l KNO3 as nitrogen source. These findings suggest the applicability of bacterial isolate Cytobacillus oceanisediminis as a potent producer of α-amylase for industrial purposes. Keywords: Amylase; Optimization; Cytobacillus oceanisediminis; Starch hydrolysis; Thermo-halophilic bacteria.

Changing of mechanical property and bearing capacity of strongly chlorine saline soil under freeze-thaw cycles

Freeze-thaw cycles and compactness are two critical factors that significantly affect the engineering properties and safety of building foundations, especially in seasonally frozen regions. This paper investigated the effects of freeze-thaw cycles on the shear strength of naturally strongly chlorine saline soil with the compactness of 85%, 90% and 95%. Three soil samples with different compactness were made. Size and mass changes were measured and recorded during freeze-thaw cycles. Shear strength under different vertical pressures was determined by direct shear tests, and the cohesion and friction angle were measured and discussed. Microstructure characteristic changes of saline soil samples were observed using scanning electron microscopy under different freeze-thaw cycles. Furthermore, numerical software was used to calculate the subsoil-bearing capacity and settlement of the electric tower foundation in the Qarhan Salt Lake region under different freeze-thaw cycles. Results show that the low-density soil shows thaw settlement deformation, but the high-density soil shows frost-heaving deformation with the increase in freeze-thaw cycles. The shear strength of the soil samples first increases and then decreases with the increase in freeze-thaw cycles. After 30 freeze-thaw cycles, the friction angle of soil samples is 28.3%, 29.2% and 29.6% lower than the soil samples without freeze-thaw cycle, the cohesion of soil samples is 71.4%, 60.1% and 54.4% lower than the samples without freeze-thaw cycle, and the cohesion and friction angle of soil samples with different compactness are close to each other. Microstructural changes indicate that the freeze-thaw cycle leads to the breakage of coarse particles and the aggregation of fine particles. Correspondingly, the structure type of soil changes from a granular stacked structure to a cemented-aggregated system. Besides, the quality loss of soil samples is at about 2% during the freeze-thaw cycles. Results suggest that there may be an optimal compactness between 90 and 95%, on the premise of meeting the design requirements and economic benefits. This study can provide theoretical guidance for foundation engineering constructions in seasonally frozen regions.

Isolation, Characterization, Evaluation and Comparative Study of Beneficial Microorganisms among the Agricultural Soil, Saline Intruded Soil and Commercial Biofertilizers

Degradation of soil health is a growing concern as both human health and soil microbial community are directly related to this. One of the main hazards to soil deterioration in Bangladesh is soil salinization. In this study, the microbiological status of two commercial biofertilizers, an agricultural soil, and saline soil in Bangladesh were analyzed and compared. Five saline soil samples from various agricultural fields in Satkhira, two commercial biofertilizer samples, and one agricultural soil from Hazi Danesh Agricultural University were collected to carry out this work. The saline soil sample's physicochemical properties, such as pH and salinity, were examined. Saline soil had a salinity range of 0.17-1.60 ppm and a pH range of 6.20-7.22. Five beneficial bacteria, three types of food-borne pathogen indicators, three types of soil quality indicators, and one plant pathogen indicator bacterium were selected for the microbiological investigation. The microbial status of the five beneficial bacteria was observed; for Rhizobium, the range was not detected to 7.62 log CFU/g, for Azotobacter, it ranged from 3.11 log CFU/g to 5.72 log CFU/g, for phosphate-solubilizing bacteria, it ranged from 3.87 log CFU/g to 4.69 log CFU/g, and for Bacillus, it was not detected to 4.65 log CFU/g. The helpful bacteria Pseudomonas spp. and the plant pathogen inhibitor Trichoderma spp., which are deemed important markers for soil health, were found to be absent in all the samples.
 The Dhaka University Journal of Earth and Environmental Sciences, Vol. 12(1), 2023, P 29-40

Mechanism of phenanthrene degradation by the halophilic Pelagerythrobacter sp. N7

PAHs has shown worldwide accumulation and causes a significant environmental problem especially in saline and hypersaline environments. Moderately halophilic bacteria could be useful for the bioremediation of PAH pollution in hypersaline environments. Pelagerythrobacter sp. N7 was isolated from the PAH-degrading consortium 5H, which was enriched from mixed saline soil samples collected in Shanxi Province, China. 16S rRNA in the genomic DNA revealed that strain N7 belonged to Pelagerythrobacter. Strain N7 exhibited a high tolerance to a wide range of salinities (1–10%) and was highly efficient under neutral to weak alkaline conditions (pH 6–9). The whole genome of strain N7 was sequenced and analyzed, revealing an abundance of catabolic genes. Using the whole genome information, we conducted preliminary research on key enzymes and gene clusters involved in the upstream and downstream PAH degradation pathways of strain N7, thereby inferring its degradation pathway for phenanthrene and naphthalene. This study adds to our understanding of PAH degradation in hypersaline environments and, for the first time, identifies a Pelagerythrobacter with PAH-degrading capability. Strain N7, with its high efficiency in phenanthrene degradation, represents a promising resource for the bioremediation of PAHs in hypersaline environments.

Experimental investigation into the salinity effect on the physicomechanical properties of carbonate saline soil

For engineering structures with saline soil as a filling material, such as channel slope, road subgrade, etc., the rich soluble salt in the soil is an important potential factor affecting their safety performance. This study examines the Atterberg limits, shear strength, and compressibility of carbonate saline soil samples with different NaHCO3 contents in Northeast China. The mechanism underlying the influence of salt content on soil macroscopic properties was investigated based on a volumetric flask test, a mercury intrusion porosimetry (MIP) test, and a scanning electron microscopic (SEM) test. The results demonstrated that when NaHCO3 contents were lower than the threshold value of 1.5%, the bound water film adsorbed on the surface of clay particles thickened continuously, and correspondingly, the Atterberg limits and plasticity index increased rapidly as the increase of sodium ion content. Meanwhile, the bonding force between particles was weakened, the dispersion of large aggregates was enhanced, and the soil structure became looser. Macroscopically, the compressibility increased and the shear strength (mainly cohesion) decreased by 28.64%. However, when the NaHCO3 content exceeded the threshold value of 1.5%, the salt gradually approached solubility and filled the pores between particles in the form of crystals, resulting in a decrease in soil porosity. The cementation effect generated by salt crystals increased the bonding force between soil particles, leading to a decrease in plasticity index and an improvement in soil mechanical properties. Moreover, this work provides valuable suggestions and theoretical guidance for the scientific utilization of carbonate saline soil in backfill engineering projects.

Halotolerant Plant Probiotic Bacterial Isolates of Mangrove Soils of Chidambaram and Thanjavur, India

Halotolerant plant growth-promoting rhizobacteria (HTPGPR) are beneficial microbes that can be exploited to mitigate the negative effects of soil salinity on crops. In the current investigation, eight saline soil samples collected from 2 mangrove ecosystems of Tamil Nadu (Chidambaram and Thanjavur) during December 2022 were used to isolate saline tolerant bacterial cultures at the Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. Using 5 different bacterial growth media, 48 rhizobacterial isolates (ST1 to ST48) were obtained. Salt tolerance ability (0, 5, 10, 15 and 20% NaCl) of these 48 isolates under in vitro conditions indicated their potential to tolerate up to 10% NaCl (1.71 M). None of the isolates could grow at 20% NaCl (3.42M). Bacterial isolates such as ST11, ST13, ST18, ST20 and ST27 showed minimum growth at 15%NaCl (2.57M). 33 isolates which could grow well at higher salt concentrations were selected. Among 33 isolates, 18 isolates with higher concentration of intracellular sodium content (ST1, ST2, ST3, ST7, ST8, ST9, ST11, ST12, ST13, ST17, ST18, ST20, ST27, ST30, ST32, ST34, ST39, and ST40) were selected and characterized qualitatively for their ability to mineralize phosphate, potassium, and zinc, and to produce HCN. Potential of these18 bacterial isolates to tolerate other abiotic stress factors such as pH and temperature was also studied. Among 18 isolates, the isolates ST7, ST17, and ST30 were found to be multimineral solubilizers. Bacterial isolate ST17 was found to prefer alkaline (pH 9.0) and mesophilic temperature (35ºC) for its growth at both saline (5% NaCl) and non saline condition.

Improving Salt Leaching in a Simulated Saline Soil Column by Compost and Biochar in Vietnamese Mekong Delta

The problem of seawater intrusion in recent years has been serious in the coastal provinces of the Vietnamese Mekong River Delta. For rice cultivation in salt-affected areas, more effective techniques are required to remediate the saline soils for lowing salinity to secure rice growth and productivity. The objective of this study was to evaluate the potential reclamation of compost and biochar in laboratory experiment using a saline soil sample from the rice cropping system. Our hypothesis was that the addition of compost and biochar might improve the infiltration rate, resulted in more effectively salts removing from saline soil. The experiment was set up with compost and biochar at rates of 5 g kg-1, 10 g kg-1 and 20 g kg-1, respectively and 10 g kg-1 compost combined with 10 g kg-1 biochar. Soil chemical characteristics such as amount of Na+, K+, Ca2+, and Mg2+ cations removed from soil into eluent by leaching, soil availabe N, P after finishing leaching were analyzed. Results indicated that all compost and biochar amendments enhanced Na+ leaching process. This study proved that material amendment such as 20g kg-1 biochar and 10g kg-1 compost plus 10g kg-1 biochar could speed up water infiltration. Compost additions increase the available N and P content in the soil after leaching. Available N and P contents have not been improved in treatments supplemented with biochar.

Composition, Abundance, and Diversity of the Soil Microbiome Associated with the Halophytic Plants Tamarix aphylla and Halopeplis perfoliata on Jeddah Seacoast, Saudi Arabia

The coast of the Red Sea in Jeddah City is home to a unique microbial community that has adapted to extreme environmental conditions. Therefore, it is essential to characterize the microbial community in this unique microbiome to predict how environmental changes will affect it. The aim of this study was to conduct metagenomic sequencing of 16S rRNA and ITS rRNA genes for the taxonomic classification of the microbial community in soil samples associated with the halophytic plants Tamarix aphylla and Halopeplis perfoliata. Fifteen soil samples were collected in triplicate to enhance robustness and minimize sampling bias. Firstly, to identify novel microbial candidates, the gDNAs were isolated from the saline soil samples surrounding each plant, and then bacterial 16S (V3–V4) and fungal ITS1 regions were sequenced utilizing a high-throughput approach (next-generation sequencing; NGS) on an Illumina MiSeq platform. Quality assessment of the constructed amplicon libraries was conducted using Agilent Bioanalyzer and fluorometric quantification methods. The raw data were processed and analyzed using the Pipeline (Nova Lifetech, Singapore) for bioinformatics analysis. Based on the total number of readings, it was determined that the phylum Actinobacteriota was the most prevalent in the soil samples examined, followed by the phylum Proteobacteria. Based on ITS rRNA gene analysis, the alpha and beta fungal diversity in the studied soil samples revealed that the fungal population is structured into various groups according to the crust (c) and/or rhizosphere (r) plant parts. Fungal communities in the soil samples indicated that Ascomycota and Basidiomycota were the two most abundant phyla based on the total amount of sequence reads. Secondly, heat-map analysis of the diversity indices showed that the bacterial alpha diversity, as measured by Shannon, Simpson, and InvSimpson, was associated with soil crust (Hc and Tc enclosing H. perfoliata and T. aphylla, respectively) and that the soil rhizosphere (Hr and Tr) was strongly correlated with bacterial beta diversity. Finally, fungal-associated Tc and Hc samples clustered together, according to observations made using the Fisher and Chao1 methods, and Hr and Tr samples clustered together according to Shannon, Simpson, and InvSimpson analyses. As a result of the soil investigation, potential agents that have been identified could lead to innovative agricultural, medical, and industrial applications.

Isolation and Characterization of Actinobacteria from Algerian Saline Soil Samples with Antimicrobial Activities

SECOND RESEARCH PAPER: Isolation and Characterization of Actinobacteria from Algerian Saline Soil Samples with Antimicrobial Activities

Halocatena marina sp. nov., a novel filamentous halophilic archaeon isolated from marine tidal flat and emended description of the genus Halocatena.

Three novel filamentous halophilic archaea, strains DFN5T, RDMS1, and QDMS1, were isolated from the coastal saline soil samples of the intertidal zones located in different regions of Jiangsu Province, China. The colonies of these strains were pinkish-white due to the presence of white spores. These three strains are extremely halophilic and grew optimally at 35-37°C and pH 7.0-7.5. Based on 16S rRNA and rpoB' gene analysis, strains DFN5T, RDMS1, and QDMS1 gathered together in phylogenetic trees and then clustered with the current species of the genus Halocatena showing 96.9-97.4% and 82.2-82.5% similarities, respectively. Both the 16S rRNA gene-based and rpoB' gene-based phylogenies were fully supported by the phylogenomic analysis, and the overall genome-related indexes indicated that strains DFN5T, RDMS1, and QDMS1 should be a novel species of the genus Halocatena. Genome mining revealed that there are considerable differences in the genes related to β-carotene synthesis among these three strains and the current species of Halocatena. The major polar lipids of strains DFN5T, RDMS1, and QDMS1 are PA, PG, PGP-Me, S-TGD-1, TGD-1, and TGD-2. The minor polar lipids, S-DGD-1, DGD-1, S2-DGD, and S-TeGD may be detected. According to the phenotypic characteristics, phylogenetic analysis, genomic and chemotaxonomic features, strains DFN5T (= CGMCC 1.19401T = JCM 35422T), RDMS1 (= CGMCC 1.19411) and QDMS1 (= CGMCC 1.19410) were classified as a novel species of the genus Halocatena with the proposed name, Halocatena marina sp. nov. This is the first report of the description of a novel filamentous haloarchaeon isolated from marine intertidal zones.

Actinobacteria as biological nitrogen fixation (BNF) and symbiotic association with actinorhizal plants for restoration of salinized soils

Soil salinity is a significant environmental problem affecting agricultural productivity worldwide. Salinized soils are one of the highest exchangeable sodium salts present in zone of the roots. In this scenario, much focus was drawn towards the symbiotic association between the plant species and the nitrogen fixing actinobacterial species. Actinobacteria are well known for their ability to produce secondary metabolites with potential applications in bioremediation and plant growth promotion. This study investigated the efficiency of co-culturing with actinobacteria to enhance the growth of plants under 0.5% NaCl conditions. Pot trials were conducted with three different treatments, fertile soil without actinobacteria, 0.5% NaCl mixed soil with actinobacteria co-culturing, and 0.5% NaCl mixed soil without actinobacteria co-culturing. The results showed that the plants grown in the 0.5% NaCl mixed soil with actinobacteria co-culturing treatment exhibited significantly plant growth, compared to the other two treatments. The co-culturing of actinobacteria was found to improve the plant's ability to tolerate high salinity conditions and enhance their growth. In this study, actinobacteria were isolated from high saline soil samples using selective media, and their morphological and biochemical characteristics were examined.

An Improved Exponential Model Considering a Spectrally Effective Moisture Threshold for Proximal Hyperspectral Reflectance Simulation and Soil Salinity Estimation

Soil salinization has become one of the main factors restricting sustainable development of agriculture. Field spectrometry provides a quick way to predict the soil salinization. However, soil moisture content (SMC) seriously interferes with the spectral information of saline soil in arid areas. It is vital to establish a model that is insensitive to SMC for potential in situ field applications. The soil spectral reflectance exponential model (SSREM) has been widely employed for reflectance simulation and SSC inversion. However, its reliability for saline soils with high SMC has not been verified yet. Based on hyperspectral remote sensing data (400~1000 nm) on 459 saline soil samples in Shiyang River Basin of Northwest China, we investigated the role of SMC and SSC in soil spectral reflectance from 29 October 2020 to 22 January 2021. Targeted at saline soils, soil spectral moisture threshold (MT) was introduced to improve the SSREM toward a modified spectral reflectance exponential model (MT-SSREM). The bands that are sensitive to SSC but not sensitive to SMC were obtained based on a method of correlation analysis between original spectra, four kinds of spectral data, and SSC. SSREM and MT-SSREM were finally applied to inversely estimate SSC. Results show that wavelengths at 658~660, 671~685, 938 nm were suitable for SSC estimation. Furthermore, although SSREM was able to simulate the spectral reflectance of most saline soils, its simulation accuracy was low for saline soil samples with high SMC (SMC > MT(i), 400 nm≤i≤1000 nm), while MT-SSREM performed well over the whole range of SMC. The simulated spectral reflectance from MT-SSREM agreed well with the measured reflectance, with the R2 being generally larger than 0.9 and RMSE being less than 0.1. More importantly, MT-SSREM performed substantially better than SSREM for SSC estimation; in the statistical performance of the former case, R2 was in range of 0.60~0.66, RMSE was in range of 0.29~0.33 dS m−1; in the latter case, R2 was in range of 0.10~0.16, RMSE was in the range of 0.26~0.29 dS m−1. MT-SSREM proposed in this study thus provides a new direction for estimating hyperspectral reflectance and SSC under various soil moisture conditions at wavelengths from 400 to 1000 nm. It also provides an approach for SSC and SMC mapping in salinization regions by incorporating remote sensing data, such as GF-5.

Haladaptatus halobius sp. nov. and Haladaptatus salinisoli sp. nov., two extremely halophilic archaea isolated from Gobi saline soil.

Two extremely halophilic archaeal strains, PSR5T and PSR8T, were isolated from a saline soil sample collected from the Tarim Basin, Xinjiang, PR China. Both strains had two copies of the 16S rRNA genes rrn1 and rrn2, showing 2.6 and 3.9% divergence, respectively. The rrn1 gene of PSR5T showed 98.4 and 95.3% similarity to the rrn1 and rrn2 genes of strain PSR8T; the rrn2 gene of PSR5T displayed 97.4 and 96.7% similarity to those of strain PSR8T, respectively. Phylogenetic analyses based on the 16S rRNA and rpoB' genes revealed that strains PSR5T and PSR8T formed a single cluster, and then tightly clustered with the current four Haladaptatus species (93.5-97.1% similarities for the 16S rRNA gene and 89.3-90.9% similarities for the rpoB' gene, respectively). Several phenotypic characteristics differentiate strains PSR5T and PSR8T from current Haladaptatus members. The polar lipids of the two strains are phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester phosphatidylglycerol sulphate and three glycolipids. One of the glycolipids is sulphated mannosyl glucosyl diether, and the remaining two glycolipids are unidentified. The average nucleotide identity, in silico DNA-DNA hybridization, amino acid identity and percentage of conserved proteins values between the two strains were 88.5, 39.1, 89.3 and 72.8 %, respectively, much lower than the threshold values proposed as a species boundary. These values among the two strains and Haladaptatus members were 77.9-79.2, 22.0-23.5, 75.1-78.2 and 56.8-69.9 %, respectively, much lower than the recommended threshold values for species delimitation. These results suggested that strains PSR5T and PSR8T represent two novel species of Haladaptatus. Based on phenotypic, chemotaxonomic, genomic and phylogenetic properties, strains PSR5T (=CGMCC 1.16851T=JCM 34141T) and PSR8T (=CGMCC 1.17025T=JCM 34142T) represent two novel species of the genus Haladaptatus, for which the names Haladaptatus halobius sp. nov. and Haladaptatus salinisoli sp. nov. are proposed.

Paenibacillus alkalitolerans sp. nov., a bacterium isolated from a salt lake of Turpan City in Xinjiang Province, north-west China.

A Gram stain-positive, rod-shaped, motile, aerobic and terminal endospore formation bacterium, designated YIM B00362T, was isolated from saline soil samples collected from a salt lake in Xinjiang Province, north-west China. Phylogenetic analysis based on the 16S rRNA gene sequences and whole genomes indicated that the isolate belongs to the genus Paenibacillus. However, the highest sequence similarity between strain YIM B00362T and the relatives was only 94.4%. Moreover, the DNA-DNA relatedness and ANI values between the novel isolate and the relative type strain, Paenibacillus antri SYSU K30003T was 13.6% and 70.3%, respectively. The major cellular fatty acids were anteiso-C15:0, C16:0 and the major quinone was MK-7. The isolate contained meso-diaminopimelic acid as the diagnostic diamino acid and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylglyceride, and two unidentified polar lipids. The genomic DNA G + C content was 50.9mol%. The major whole-cell sugars contained glucose and galactose. On the basis of physiological, phenotypic, and chemotaxonomic data, strain YIM B00362T represents a novel species of genus Paenibacillus, for which the name Paenibacillus alkalitolerans sp. nov. is proposed. The type strain is YIM B00362T (= KCTC 43272T = CGMCC 1.18801T = NBRC 114667T).

Feasibility Study of Petrochemical Waste and Cement Usage for Saline Road Subgrade Stabilisation

The widespread distributions of saline soils in Iran cause a range of problems for road construction projects due to insufficient shear strength, salt solubility potential and swelling. This paper conducts experimental tests using different cement contents and a sort of petrochemical waste with two curing methods to stabilise saline soil samples. Strength, compressibility and chemical tests were conducted, X-ray diffraction analyses were performed, and scanning electron microscope pictures were prepared for basic materials and stabilised saline soil samples in this paper. The results indicate that both petrochemical soda ash waste and cement enhance the shear strength of saline soil, especially after 28 days of curing. However, the combination is more appropriate from the swelling and salt solubility potential viewpoint. The optimum combination of 2% cement and 5% of petrochemical soda ash waste, cured by method 2 for 28 days, results in the most significant shear strength enhancement (127%). Furthermore, a swelling quantity of the optimum combination is reasonably restricted. X-ray diffraction test results and scanning electron microscope pictures demonstrated that despite the presence of ettringite agents, the formation quantity of these minerals is negligible. The salt is well stabilised, and its solubility potential dramatically decreases.

Characterization of Halophilic Bacteria Isolated from Khewra Salt Mines

Halophilic bacteria can populate every niche of earth. These halophiles have a great potential of exopolysaccharides production that is of considerable importance in various industries. To screen EPS producing halophiles, saline soil samples were collected from Khewra salt mines, Jehlum, Pakistan. Twenty-two morphologically different bacterial strains were isolated by serial dilution method. All strains were considered as moderate halophilic bacteria as they could grow at 3-15% of NaCl concentration whereas only three strains could grow at 15% of NaCl, which belonged to the genus Bacillus and Pseudomonas. For screening of EPS production, P-medium was used. While for the estimation of slime production, congo-red agar was used that exhibited positive results by appearance of black colored colonies by many strains. Moreover, EPS production was analyzed quantitatively and qualitatively. Isolated Staphylococcus and Bacillus species produced high amount of EPS (20g/L). “Moderate halophiles” play an important role in therapeutics, bioremediation, food and medicine, petroleum and tanning industries by producing EPS. Recently, growth of many agriculture crops has been improved by using beneficial halophiles in saline soils. Consequently, with the help of these beneficial halophiles we can give benefit to mankind

Genome-based taxonomy of genera Halomicrobium and Halosiccatus, and description of Halomicrobium salinisoli sp. nov

The genera Halosiccatus and Halomicrobium are the most closely related genera within the family Haloarculaceae (class Halobacteria). All species of these two genera are closely related to each other in phylogenetic analyses based on their 16S rRNA gene sequences, and also using the sequences of four housekeeping genes. The genus Halosiccatus was proposed based on inferred phylogeny using only one of the three distinct 16S rRNA genes detected in strain DC8T, while Halomicrobium zhouii, one of three species of Halomicrobium, was omitted from the reference species used in these analyses. The related 16S rRNA gene sequence similarities of type strains of Halomicrobium katesii and Halomicrobium mukohataei were as high as 99.5%–99.7%, much higher than the threshold values proposed as species boundaries. These issues could have resulted in taxonomic inaccuracies in the genera Halosiccatus and Halomicrobium, and a thorough study was undertaken to clarify the status of all species in both genera. Based on phylogenetic and phylogenomic analyses, the current four species of the two genera form a single clade with high bootstrap confidence, indicating that the genus Halosiccatus should be merged with Halomicrobium. Halomicrobium katesii Kharroub et al. 2008 is proposed as a later heterotypic synonym of Halomicrobium mukohataei (Ihara et al. 1997) Oren et al. 2002. An additional species is also described (strains LT50T and TH30), and was isolated from different Gobi saline soil samples of Tarim Basin, Xinjiang, China. Phenotypic, chemotaxonomic, genomic and phylogenetic properties indicated that strains LT50T (=CGMCC 1.15187T = JCM 30837T) and TH30 (=CGMCC 1.15189 = JCM 30839) represent a novel species of the genus Halomicrobium, for which the name Halomicrobium salinisoli sp. nov. is proposed.

Sporosarcina jiandibaonis sp. nov., isolated from saline soil.

A Gram-stain-positive, aerobic, motile, rod-shaped bacterium, designated strain LAM9210T, was isolated from a saline soil sample collected from Lingxian County, Shandong Province, PR China. Analysis of the 16S rRNA gene sequence of the isolate revealed highest sequence similarities to the type strain of Sporosarcina pasteurii NCIMB 8841T (97.6 % sequence similarity). The genomic G+C content was 40.4 mol%. The average nucleotide identity and in silico DNA-DNA hybridization values between strain LAM9210T and the type strain of the most closely related species S. pasteurii NCIMB 8841T were 73.6 and 20.6 %, respectively. Strain LAM9210T was found to grow at 10-40 °C (optimum, 30 °C), at pH 6.0-10.0 (optimum, pH 9.0) and with 0-6 % (w/v) NaCl (optimum, 0.5 %), respectively. The major fatty acids were anteiso-C15 : 0 and iso-C14 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and one unidentified phospholipid. Menaquinone-7 was detected as the predorminant respiratory quinone. Strain LAM9210T contained glycine, lysine, alanine and glutamic acid as the diagnostic amino acids in the cell-wall peptidoglycan. On the basis of phenotypic, phylogenetic and genotypic data, strain LAM9210T is considered to represent a novel species of the genus Sporosarcina, for which the name Sporosarcina jiandibaonis sp. nov. is proposed. The type strain is LAM9210T (=CGMCC 1.18607T=GDMCC 1.2002T=JCM 32514T).