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PubMed2026

Long-term saline-alkaline selection rewires the growth-survival trade-off in Priestia megaterium.

Saline-alkaline soils impose persistent osmotic, ionic, pH, and nutrient stress on soil microorganisms, but the evolutionary routes by which beneficial bacteria adapt to such conditions remain poorly resolved. We performed adaptive laboratory evolution to examine the adaption of the plant growth-promoting rhizobacterium Priestia megaterium HA22 to long-term oligotrophic saline-alkaline selection. After 175 serial transfers, the evolved lineage proliferated stably at 40 g L-1 Na2SO4 at pH 10.0, whereas the wild-type strain failed to proliferate. Genome resequencing and allelic replacement revealed a 5-bp insertion in spo0A, the master sporulation regulator, as a major adaptive mutation. This mutation abolished sporulation; shortened the lag phase; and enhanced vegetative growth, nutrient uptake, and expression of tricarboxylic acid cycle and nitrogen metabolism gene under saline-alkaline stress. According to untargeted metabolomics, adaptation was accompanied by increased amino acid metabolism and aminoacyl-tRNA biosynthesis, with proline, isoleucine and pantothenic acid functionally promoting growth. A point mutation in ugpB enhanced glycerol-3-phosphate uptake, increased peptidoglycan and wall teichoic acid levels, and partially rescued the survival cost of the spo0A mutation. In greenhouse assays under combined saline-alkaline stress, the evolved strain increased soybean shoot dry weight and root dry weight by 56.08% and 27.02%, respectively. These results indicate that prolonged, predictable saline-alkaline selection can favor active growth rather than dormancy when compensatory cell envelope reinforcement buffers survival costs.

Adaptive laboratory evolution↗

PubMed2002

Paleosols and paleoenvironments of the middle Miocene, Maboko Formation, Kenya.

The middle Miocene (15 Ma) Maboko Formation of Maboko Island and Majiwa Bluffs, southwestern Kenya, has yielded abundant fossils of the earliest known cercopithecoid monkey (Victoriapithecus macinnesi), and of a kenyapithecine hominoid (Kenyapithecus africanus), as well as rare proconsuline (Simiolus leakeyorum, cf. Limnopithecus evansi) and oreopithecine apes (Mabokopithecus clarki, M. pickfordi), and galagids (Komba winamensis). Specific habitat preferences can be interpreted from large collections of primate fossils in different kinds of paleosols (pedotypes). Fossiliferous drab-colored paleosols with iron-manganese nodules (Yom pedotype) are like modern soils of seasonally waterlogged depressions (dambo). Their crumb structure and abundant fine root-traces, as well as scattered large calcareous rhizoconcretions indicate former vegetation of seasonally wet, wooded grassland. Other fossiliferous paleosols are evidence of nyika bushland (Ratong), and early-successional riparian woodland (Dhero). No fossils were found in Mogo paleosols interpreted as saline scrub soils. Very shallow calcic horizons (in Yom, Ratong, and Mogo paleosols) and Na-montmorillonite (in Mogo) are evidence of dry paleoclimate (300-500 mm MAP=mean annual precipitation). This is the driest paleoclimate and most open vegetation yet inferred as a habitat for any Kenyan Miocene apes or monkeys. Victoriapithecus was abundant in dambo wooded grassland (Yom) and riparian woodland (Dhero), a distribution like that of modern vervet monkeys. Kenyapithecus ranged through all these paleosols, but was the most common primate in nyika bushland paleosols (Ratong), comparable to baboons and macaques today. Mabokopithecus was virtually restricted to riparian woodland paleosols (Dhero), and Simiolus had a similar, but marginally wider, distribution. Habitat preferences of Mabokopithecus and Simiolus were like those of modern colobus monkeys and mangabeys. A single specimen of Komba was found in dambo wooded grassland paleosol (Yom), a habitat more like that of the living Senegal bushbaby than of rainforest galagids. A shift to non-forest habitats may explain the terrestrial adaptations of Victoriapithecus, basal to the cercopithecid radiation, and of Kenyapithecus, basal to the hominoid radiation. Both taxa are distinct from earlier Miocene arboreal proconsulines, oreopithecines and galagids.

Animals↗

PubMed1978

Effect of freezing and thawing on survival of three bacterial isolates from an arctic soil.

Three isolates, a Pseudomonas sp., Bacillus sp., and Arthrobacter sp., which had been isolated from a meadow soil at Devon Island, Canada, were subjected to freezing and thawing at low rates under various conditions. When cells were frozen in sand or soil, survival was dependent on moisture level, storage time, and thaw rate. Pseudomonas M216 was most susceptible to freeze-thaw damage under these conditions. Arthrobacter M51 was the most resistant of the three isolates when frozen in sand or soil and when frozen at a high rate after growth at varing rates at 5 and 15 degrees C in carbon-or nitrogen-limited media. Pseudomonas M216 was more sensitive to freeze-thaw damage when NaCl was present in the freezing menstruum, even at low freezing rates. Survival of cells frozen in growth medium, water, saline, and soil extract was not affected by the freezing rate when it was less than 1 degrees C min-1. Soil extract did not protect cells from freeze-thaw damage any more than water and for Arthrobacter M51 survival was decreased when it was frozen in soil extract.

Arctic Regions↗

PubMed2001

Regional planning for the siting of local evaporation basins for the disposal of saline irrigation drainage: development and testing of a GIS-based suitability approach.

In order to prevent salinisation of the streams of the Riverine Plain of the Murray-Darling Basin in southern Australia, evaporation basins are used to dispose of saline irrigation drainage water. Local on-farm (individual landholder) and community (shared between multiple landholders) basins are increasingly being used to prevent export of salt outside irrigation districts. There are questions regarding the availability of land suitable for these basins and their impact on the surrounding environment. We describe the use of currently available spatial data to assist in regional planning for the environmentally safe use of these basins. A GIS-based approach was developed using suitability criteria expected to minimise the risk of off-site effects of basin leakage. The criteria were proximity to surface water features, urban areas and infrastructure, water table depth and salinity, and soil hydraulic conductivity. The approach was applied to all of the major irrigation districts at 1:250,000, the scale at which data are available over the entire Riverine Plain. Confidence in well-defined parameters such as proximity to infrastructure, urban areas and surface water features was higher than for those involving interpolated point data such as water table depth, salinity, and hydraulic conductivity. Most critically, hydraulic conductivity, the most important factor for basin leakage, was found to be unreliable at this scale. Use of higher resolution data (up to 1:100,000) available for two of the irrigation districts improved confidence in both water table depth and salinity but not in hydraulic conductivity. Despite these limitations, it was found that: (i) on-farm basins can only be used on an opportunistic basis in the eastern irrigation districts, but can be widely used in the western districts; (ii) community basins can be used anywhere there is suitable land; and (iii) the results raise serious questions as to whether there is enough suitable land in the eastern districts to dispose of all of the drainage water that is produced.

Agriculture↗

PubMed2006

Environment or development? Lifetime net CO2 exchange and control of the expression of Crassulacean acid metabolism in Mesembryanthemum crystallinum.

The relative influence of plant age and environmental stress signals in triggering a shift from C(3) photosynthesis to Crassulacean acid metabolism (CAM) in the annual halophytic C(3)-CAM species Mesembryanthemum crystallinum was explored by continuously monitoring net CO(2) exchange of whole shoots from the seedling stage until seed set. Plants exposed to high salinity (400 mm NaCl) in hydroponic culture solution or grown in saline-droughted soil acquired between 11% and 24% of their carbon via net dark CO(2) uptake involving CAM. In contrast, plants grown under nonsaline, well-watered conditions were capable of completing their life cycle by operating in the C(3) mode without ever exhibiting net CO(2) uptake at night. These observations are not consistent with the widely expressed view that the induction of CAM by high salinity in M. crystallinum represents an acceleration of preprogrammed developmental processes. Rather, our study demonstrates that the induction of the CAM pathway for carbon acquisition in M. crystallinum is under environmental control.

Carbon Dioxide↗

PubMed2004

Influence of the carbon/nitrogen/phosphorus ratio on polycyclic aromatic hydrocarbon degradation by Mycobacterium and Sphingomonas in soil.

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the environment is often limited due to unfavorable nutrient conditions for the bacteria that use these PAHs as sole source of carbon and energy. Mycobacterium and Sphingomonas are 2 PAH-degrading specialists commonly present in PAH-polluted soil, but not much is known about their specific nutrient requirements. By adding different inorganic supplements of nitrogen (N) and phosphorus (P), affecting the overall carbon/nitrogen/phosphorus ratio of soil in soil slurry degradation tests, we investigated the impact of soil inorganic N and P nutrient conditions on PAH degradation by PAH-degrading Sphingomonas and Mycobacterium strains. The general theoretically calculated C/N/P ratio of 100/10/1 (expressed in moles) allowed rapid PAH metabolization by Sphingomonas and Mycobacterium strains without limitation. In addition, PAH-degradation rate and extent was not affected when ca. ten times lower concentrations of N and P were provided, indicating that Sphingomonas and Mycobacterium strains are capable of metabolizing PAHs under low nutrient conditions. Nor does PAH-degradation seem to be affected by excesses of N and P creating an imbalanced C/N/P ratio. However, supplements of N and P salts increased the salinity of soil slurry solutions and seriously limited or even completely blocked biodegradation.

Biodegradation, Environmental↗

PubMed1991

Selenium accumulation and selenium tolerance of salt grass from soils with elevated concentrations of Se and salinity.

Biomass production, selenium accumulation, and the role of the bioextraction of selenium by salt grass (Distichlis spicata L.) in soils with elevated concentrations of Se and salinity at Kesterson, California, were studied. Salt grass contributed more than 80% vegetative coverage and 90% dry weight in the grassland communities where the soil Se concentrations were 100 times (1000 to 3000 micrograms kg-1) higher than the Se concentrations found in soils of the control sites. No evidence for evolution of Se tolerance was found in the salt grass populations. The successful colonization of salt grass in the soil with elevated Se and salinity is attributable to the presence of high concentrations of soil sulfate. Salt grass accumulated less Se than other salt-tolerant plant species existing in the same area, and no predation of animals and insects on salt grass has been noticed. Salt grass can transpire substantial amounts of volatile Se through its plant tissue. Under field conditions, a 1-m2 salt grass plot may produce 180 micrograms volatile selenium per day. However, no reduction of soil Se concentration in the salt grass habitat was detected over a period of 1 year. A long-term monitoring of Se status is needed in order to make predictions of the effectiveness of efforts to clean up Se-contaminated soils through the use of native plant species.

Chlorides↗

PubMed1996

Relationship Between Abundance of N2-fixing Cyanobacteria and Environmental Features of Spanish Rice Fields

In order to estimate the potential utilization of N2-fixing (heterocystous) cyanobacteria as natural biofertilizers in the Valencian rice fields (Spain), the distribution and seasonal variation of these microorganisms in water and sediment samples were evaluated, and the relationships among cyanobacterial abundance and physical and chemical characteristics of soil and water were investigated. N2-fixing cyanobacteria were present in all the samples analyzed (25 sampling points sampled three times per year during two years). The relative cyanobacterial abundance in soil and water followed contrasting patterns, maximum presence in soil coincided with minimum abundance in water. Correlation analysis showed that cyanobacterial abundance in the two phases (water and sediment) was influenced more by water than by soil properties. Salinity,mineralization variables, and soluble reactive phosphate (SRP) correlated positively with heterocystous cyanobacteria presence. Furthermore, dissolved inorganic nitrogen (DIN) and the ratio DIN:SRP correlated negatively with cyanobacterial abundance. However DIN:SRP ratio better described the cyanobacterial distribution, with a threshold effect: below the Redfield ratio value (7.2 in mass units) cyanobacterial abundance was clearly higher.

Journal Article↗

PubMed2026

Comparative metagenomic analysis of microbial communities: unravelling microbial communities from the great Rann of Kachchh and coastal saltpans, Gujarat, India.

Hypersaline environments exhibit extreme physiochemical conditions yet support diverse microbial communities. These communities are not only ecologically important but also possess substantial potential for biotechnological exploitation. In this study, we employed a comparative metagenomic approach to assess microbial diversity using two distinct methodologies: (1) direct DNA extraction from raw sediment, and (2) DNA extraction following halophilic enrichment in selective media. Sediment samples were collected from multiple sites and pooled together within the Rann of Kachchh and close-by saltpans and were analysed using 16S rRNA sequencing coupled with bioinformatics pipelines. The results revealed pronounced differences in microbial community composition between the two approaches. Raw sediment samples exhibited significantly higher alpha diversity, with dominant taxa including Halobacterota, Cyanobacteria, and Desulfobacterota, with a substantial proportion of unclassified genera. In contrast, enriched samples were dominated by fast-growing, culturable genera such as Halobacterium, Alkalibacillus, and Candidatus haloredivivus. Principal Coordinate Analysis (PCoA) of beta diversity demonstrated distinct clustering between raw and enriched communities, even within samples from the same sites, underscoring the selective bias introduced by enrichment procedures. These findings emphasise that the methodological choice strongly influences the observed microbial diversity. The aim of this study was to compare microbial community composition in raw hypersaline sediments and enrichment cultures using metagenomic sequencing, to evaluate how enrichment selectively favours specific halophilic taxa. This comparative approach allows identification of the microbial groups that rapidly proliferate under controlled hypersaline conditions, thereby complementing direct environmental sequencing. By integrating both direct and enrichment-based metagenomic approaches, a more comprehensive understanding of microbial community structure in hypersaline environments can be achieved.

India↗

PubMed2006

Global attention to Turkey due to desertification.

Desertification has recognized as an environmental problem by many international organizations such as UN, NATO and FAO. Desertification in Turkey is generally caused by incorrect land use, excessive grazing, forest fires, urbanization, industry, genetic erosion, soil erosion, salinization, and uncontrolled wild type plants picking. Due to anthropogenic destruction of forest, steppe flora gradually became dominant in Anatolia. In terms of biodiversity, Turkey has a significant importance in Europe and Middle East. Nine thousands plant species naturally grown in Turkey, one third of them are endemic. Also, endemic species of vertebrates, thrive in the lakes and marshy areas. The studies of modelling simulation of vegetation on the effects of Mediterranean climate during the Roman Classical period by using vegetation history showed that, in 2000 years BP, Mediterranean countries were more humid than today. Turkey is a special place on the global concern in terms of desertification because of biodiversity, agricultural potential, high population, social and economical structure, topographical factors and strategic regional location. Communication among scientists, decision makers and international non-profit organizations must be improved.

Climate↗

PubMed2006

Improved production of alkaline protease from a mutant of alkalophilic Bacillus pantotheneticus using molasses as a substrate.

An alkalophilic bacterial isolate identified as Bacillus pantotheneticus, isolated from saline-alkali soils of Avadh region of UP, India, was studied for the production of alkaline protease. The mutant of the isolated species showed 44% improved production over the parent strain. Organic nitrogen sources supported better protease production than the inorganic sources. The production of alkaline protease was (242 U/ml) in the medium containing molasses, which was comparable with molasses and wheat bran (285 U/ml) as carbon and nitrogen sources, respectively. Protease production was best at pH 10 and temperature 30 degrees C. The Km (for casein) was 11 mg/ml and Vmax was 380-microg tyrosine/ml/min. The enzyme was stable between pH 7 and 10.7 and temperature between 30 and 60 degrees C with a pH and temperature optimum at 8.4 and 40 degrees C, respectively. The results indicated that molasses was an optimal substrate for alkaline protease production.

Bacillus↗

PubMed2026

Biocontrol efficacy of Bacillus albus SSR3 for controlling postharvest fungal pathogens and mycotoxin contamination.

Sweetpotato black rot, caused by Ceratocystis fimbriata, is a major postharvest disease that leads to substantial storage losses worldwide. In this study, a salt-tolerant rhizobacterial strain, Bacillus albus SSR3, was isolated from the rhizosphere of sweetpotato grown in saline-alkali soil, with broad-spectrum antagonistic activity against postharvest fungal pathogens. LC-MS/MS analysis revealed diverse bioactive metabolites associated with its antifungal activity. Integrated transcriptomic and metabolomic analyses showed that SSR3 bioactive metabolites extensively reprogrammed fungal metabolism, particularly pathways involved in carbohydrate and amino acid metabolism, antioxidant defense, and energy production. These alterations were accompanied by disruption of cell wall and membrane integrity, excessive reactive oxygen species accumulation, and mitochondrial dysfunction, ultimately inhibiting fungal growth. Here, we also found that SSR3 bioactive metabolites effectively inhibited aflatoxin B1 production by Aspergillus flavus and deoxynivalenol accumulation in Fusarium graminearum. In vivo assays further demonstrated that SSR3 bioactive metabolites significantly reduced sweetpotato black rot severity and effectively limited fungal colonization and mycotoxin contamination in stored agricultural commodities. Collectively, our findings demonstrate that B. albus SSR3 suppresses postharvest fungal pathogens through coordinated metabolic reprogramming, oxidative stress induction, and cellular integrity disruption, highlighting its potential as a sustainable biocontrol agent for postharvest disease management.

Bacillus albus↗

PubMed2003

Effects of leaching parameters on swelling behaviors of compacted mudstone used in landfill liner.

This study attempt to determine the swelling deformation of compacted mudstone using the free swell test, and the leaching parameters using a pH meter, a conductivity meter, and ion chromatography (IC) techniques. Closely examining chemical characteristics indicated that natural mudstone is saline-alkali soil. The maximum swelling deformation obtained from the free swell test is about 15.7%. The swelling developed relatively rapidly after the start of soaking, stopping after 7 days. The leaching characteristics in compacted mudstone involve the hydrolysis of Na+ ions, the precipitation of CaCO3 and slightly dissolution of Mg2+ ion. The relationship of swelling deformation to sodium adsorption ratio (SAR) value indicated that the SAR value in soaking suspension significantly affects the amount of swelling. Additionally, the pH of the soaking suspension importantly affects swelling behavior. Overall, the early swelling behaviors of compacted mudstone are posited to involve directly the concentration of Na+ ions in the soaking suspension and the precipitation of CaCO3 in compacted mudstone. Furthermore, the very slight swelling after the 3-day soaking is related to the dissolution of Mg2+ ions in compacted mudstone.

Aluminum Silicates↗

PubMed1995

Characteristics of Rhizobium tianshanense sp. nov., a moderately and slowly growing root nodule bacterium isolated from an arid saline environment in Xinjiang, People's Republic of China.

We performed a numerical analysis of 148 phenotypic characteristics of 20 strains of root nodule bacteria isolated from an arid saline desert soil in the Xinjiang region of northwestern People's Republic of China and compared these organisms with 28 Rhizobium and Bradyrhizobium strains obtained from different regions of the People's Republic of China and from other countries, including nine type strains of different species. All of the strains examined clustered into two groups at a similarity level of more than 63%. Group I included all of the previously described Rhizobium species and was divided into eight subgroups, which corresponded to previously described Rhizobium species, at a similarity level of more than 82%. Group II was divided into the following three subgroups at a similarity level of more than 80% Bradyrhizobium japonicum, a cluster containing 17 moderately and slowly growing strains isolated in the Xinjiang region, and a small subgroup containing three fast-growing strains. The generation times of the moderately and slowly growing strains were 5 to 15 h, and these organisms produced acid in medium containing mannitol. The DNA G+C contents of the members of this group ranged from 59 to 63 mol%. DNA-DNA hybridization experiments revealed that the levels of DNA homology among all of the moderately and slowly growing strains obtained from Xinjiang were more than 70% and that the levels of DNA homology between representative strains of this group and the type strains of all previously described species of root- and stem-nodulating bacteria were low.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Composition↗

PubMed2026

Circle-seq analysis reveals the involvement of eccDNAs in salt stress response of bermudagrass (Cynodon dactylon).

Extrachromosomal circular DNAs (eccDNAs) have been identified in a wide variety of plant species and play a pivotal role in genomic plasticity, emerging as key drivers of stress adaptation. However, the putative roles of eccDNAs under environmental stress remain largely unexplored in plants. As a high-quality turfgrass, bermudagrass (Cynodon dactylon L.) is a pivotal species for the reclamation and improvement of saline-alkali soils. Therefore, we performed a comprehensive analysis of the eccDNA profiles in bermudagrass under salt stress. A total of 1,068 eccDNAs were identified across all chromosomes. These eccDNAs were characterized by short lengths (ranging from 100 bp to 1 kb) and low GC content. Their genomic distribution was not entirely random but rather exhibited a certain preference for intergenic regions and coding sequences (CDS). Crucially, null model analysis of A/T-rich junction sites revealed that these eccDNAs primarily originate from physically unstable scaffold/matrix attachment regions (S/MARs) via stochastic fragmentation, followed by opportunistic circularization predominantly mediated by the non-homologous end joining (NHEJ) pathway. Notably, salt stress specifically enriched eccDNAs derived from DNA transposons, including the Tc1/Mariner, CACTA and MITE superfamilies. Overall, our findings reveal complex extrachromosomal structural dynamics in bermudagrass, offering novel insights into its genomic adaptation under environmental stress.

Cynodon↗

PubMedDate not supplied

Sources of salinity near a coal mine spoil pile, north-central Colorado.

A small (1 km2) salt-affected stream drainage on the High Plains north of Denver, Colorado was sampled to determine the near-surface dispersion of soluble salts and metals from low-sulfur coal mining waste (spoil). Surface waters collected along the 0.8-km stream reach, and aqueous leachates of spoil and naturally saline local soil, were analyzed for chemical constituents and sulfur isotopes. In this semiarid setting with abundant carbonate-bearing surficial sediments, the limited, mildly acidic drainage from the spoil pile is quickly neutralized, restricting the mobility of many elements. However, some spoil-derived constituents were clearly traceable within the upper 0.4 km of the stream reach. Spoil leachates and surface water near the spoil pile have distinctive compositions of major anions and cations, and elevated levels of dissolved nitrate compared with downstream waters. Spoil-derived sulfate was traceable because it has generally positive values of delta34S that contrasted with generally negative values of delta34S in soil leachates and evaporite salts from the surrounding area. Spatial-chemical sampling of surface water showed an abrupt increase in dissolved U, Se, B, Li, and Mn in the lower 0.4 km of the stream reach where shallow ground water from surrounding irrigated fields contributed to surface flow. The downstream evolution of surface water chemistry and sulfur isotopic composition is consistent with mixing between spoil-affected upstream water and irrigation-return water. The methods described should be applicable at other sites in similar settings where the environmental effect of low-sulfur coal mining waste must be assessed and where access to samples of shallow ground water is limited.

Coal↗

PubMed2004

Assessment of China's economic loss resulting from the degradation of agricultural land in the end of 20th century.

Land degradation is a consequence stemming from both natural processes and social economic activities. On the bases of analyzing general situation of agricultural land degradation in China, the monetary estimating methods such as market value method and shadow engineering method were used to quantitatively assess the economic loss resulting from land deterioration. Results showed that the economic loss in 1999 was 326.81 billion RMB Yuan, which accounted for 4.1% of GDP in the same year of China. If taking five items namely farmland conversion, soil erosion, salinization, decline in reservoir functions, and siltation in waterways and, comparing with that in 1992, the percentage of economic loss to GDP has increased by 1.5 in the only 7 years.

Agriculture↗

PubMed1984

[Precancerous conditions of the stomach in inhabitants of the Kalmyk ASSR].

A study involving the use of acidity test of gastric secretion in healthy population living in the four areas of the Kalmyk ASSR characterized by different natural conditions and different rates of stomach cancer incidence established a correlation between a higher frequency of this disease, on the one hand, and enhanced rates of anacidity as well as higher salinity of soil and water, on the other.

Adult↗