Physicochemical Environment Research Articles

Yielding behaviour of chemically treated Pseudomonas fluorescens biofilms

The mechanics of biofilms are intrinsically shaped by their physicochemical environment. By understanding the influence of the extracellular matrix composition, pH and elevated levels of cationic species on the biofilm rheology, novel living materials with tuned properties can be formulated. In this study, we examine the role of a chaotropic agent (urea), two divalent cations and distilled deionized water on the nonlinear viscoelasticity of a model biofilm Pseudomonas fluorescens. The structural breakdown of each biofilm is quantified using tools of non-linear rheology. Our findings reveal that urea induced a softening response, and displayed strain overshoots comparable to distilled deionized water, without altering the microstructural packing fraction and macroscale morphology. The absorption of divalent ferrous and calcium cations into the biofilm matrix resulted in stiffening and a reduction in normalized elastic energy dissipation, accompanied by macroscale morphological wrinkling and moderate increases in the packing fraction. Notably, ferrous ions induced a predominance of rate dependent yielding, whereas the calcium ions resulted in equal contribution from both rate and strain dependent yielding and structural breakdown of the biofilms. Together, these results indicate that strain rate increasingly becomes an important factor controlling biofilm fluidity with cation-induced biofilm stiffening. The finding can help inform effective biofilm removal protocols and in development of bio-inks for additive manufacturing of biofilm derived materials.

The underground network: facilitation in soil bacteria

Our understanding of the fundamental role that soil bacteria play in the structure and functioning of Earth's ecosystems is ever expanding, but insight into the nature of interactions within these bacterial communities remains rudimentary. Bacterial facilitation may enhance the establishment, growth, and succession of eukaryotic biota, elevating the complexity and diversity of the entire soil community and thereby modulating multiple ecosystem functions. Global climate change often alters soil bacterial community composition, which, in turn, impacts other dependent biota. However, the impact of climate change on facilitation within bacterial communities remains poorly understood even though it may have important cascading consequences for entire ecosystems. The wealth of metagenomic data currently being generated gives community ecologists the ability to investigate bacterial facilitation in the natural world and how it affects ecological systems responses to climate change. Here, we review current evidence demonstrating the importance of facilitation in promoting emergent properties such as community diversity, ecosystem functioning, and resilience to climate change in soil bacterial communities. We show that a synthesis is currently missing between the abundant data, newly developed models and a coherent ecological framework that addresses these emergent properties. We highlight that including phylogenetic information, the physicochemical environment, and species‐specific ecologies can improve our ability to infer interactions in natural soil communities. Following these recommendations, studies on bacterial facilitation will be an important piece of the puzzle to understand the consequences of global change on ecological communities and a model to advance our understanding of facilitation in complex communities more generally.

Sonodynamic and sonomechanical effect on cellular stemness and extracellular physicochemical environment to potentiate chemotherapy

BackgroundHypoxia-activated prodrug (HAP) is a promising candidate for highly tumor-specific chemotherapy. However, the oxygenation heterogeneity and dense extracellular matrix (ECM) of tumor, as well as the potential resistance to chemotherapy, have severely impeded the resulting overall efficacy of HAP.ResultsA HAP potentiating strategy is proposed based on ultrasound responsive nanodroplets (PTP@PLGA), which is composed of protoporphyrin (PpIX), perfluoropropane (PFP) and a typical HAP, tirapazamine (TPZ). The intense vaporization of PFP upon ultrasound irradiation can magnify the sonomechanical effect, which loosens the ECM to promote the penetration of TPZ into the deep hypoxic region. Meanwhile, the PpIX enabled sonodynamic effect can further reduce the oxygen level, thus activating the TPZ in the relatively normoxic region as well. Surprisingly, abovementioned ultrasound effect also results in the downregulation of the stemness of cancer cells, which is highly associated with drug-refractoriness.ConclusionsThis work manifests an ideal example of ultrasound-based nanotechnology for potentiating HAP and also reveals the potential acoustic effect of intervening cancer stem-like cells.Graphical

Macroalgal presence decreases coral calcification rates more than ocean acidification

Global coral reef degradation has precipitated phase shifts toward macroalgal-dominated communities. Despite the negative repercussions for reefscapes, higher abundances of primary producers have the potential to positively impact the physicochemical environment and mitigate negative impacts of ocean acidification (OA). In this study, we investigated the influence of macroalgal (cf. Sargassum vulgare) density on coral (Acropora millepora and A. hemprichii) calcification rates under current and future OA conditions. Corals were resistant to OA up to ~ 1100 µatm, with no changes in calcification rates. However, the presence of (low and high density) algae reduced calcification rates by ~ 41.8%, suggesting either a chemical defense response due to algal metabolites or potential physical impacts from shading or abrasion. Documented beneficial buffering effects of macroalgae in OA may also elicit negative impacts on coral calcification, suggesting further work is needed to elucidate how species interactions influence responses to projected climate change.

Exploring microstructure variations and hydrogen storage characteristics in TiVNbCrNi high-entropy alloys with different Ni incorporation

In recent years, high-entropy alloys (HEAs), as a novel class of hydrogen storage materials, have been deemed highly promising due to their extensive compositional tunability and the unique high entropy effects. This study aims to enhance the comprehensive hydrogen storage performance of the TiVNbCr-based HEA by introducing Ni. The effects of Ni addition on the microstructural evolution of the alloy and its impact on activation properties, hydrogen absorption and desorption kinetics, thermodynamics, and cycling performance under the complex physicochemical environment of multiple principal elements was systematically investigated. The findings indicate that Ni addition shortens the activation incubation period of the alloy but more Ni reduces the intrinsic hydrogen absorption kinetics. In the Ti25V30Nb10Cr33Ni2 alloy, a high reversible hydrogen storage capacity of up to 2.2 wt% at room temperature was achieved, surpassing most of the currently reported body-centered cubic (BCC)-structured high-entropy hydrogen storage alloys. Furthermore, the influence of Ni on the alloy's hydrogen desorption kinetics and cycling hydrogenation performance was studied. Results from 110 cycles of testing reveal that the introduction of Ni-induced Laves phases can act to relax stress, thereby reducing strain accumulation during the hydrogen absorption and desorption cycling process. This could provide guidance for the design of high-entropy hydrogen storage alloys with extended cycling lifetimes.

Statistical analysis of earth observing data for physicochemical water quality parameters estimation for Lake Beseka, Northern main Ethiopian rift, Ethiopia

ABSTRACT Water quality deterioration in the Main Ethiopian Rift Lakes is one of the problems affecting the health and socioeconomic development of the area. This study was aimed to develop a method to assess the water quality change of Lake Beseka using satellite image reflectance data and observed data. Multi-temporal Landsat imagery and three variables were used to assess the physicochemical environment: pH, EC, and TDS. Linear regression and correlation were accomplished between observed water quality parameters and surface reflectance of different band operations. The best-fitted linear regression equation for pH was found on SWIR1 while for EC and TDS, the blue/green band ratio was highly fitted. The Pearson coefficients of correlation for pH, EC, and TDS were − 0.79, 0.86, and 0.85, respectively. The RMSE and p-value for validation analysis were 0.25/0.005, 548/0.003, and 367/0.004 for pH, EC, and TDS, respectively. The estimated pH, EC, and TDS were higher in the central portion of the lake grouped under brackish water and lower in the southwestern, southern, and northeastern shores. The estimated EC and TDS for the years 2018 and 2021 were relatively lower than in 2007 and 2023. The spatiotemporal lake water variations were due to anthropogenic and geogenic factors including hot springs and groundwater discharge to the lake, water-level rise and depth variation, and evaporation. These findings are helpful for understanding linear regression equations that developed from surface reflectance and observed data, which are essential to estimating and monitoring water quality change in a cost-effective and time-saving manner.

Identification of Low-Complexity Domains by Compositional Signatures Reveals Class-Specific Frequencies and Functions Across the Domains of Life.

Low-complexity domains (LCDs) in proteins are typically enriched in one or two predominant amino acids. As a result, LCDs often exhibit unusual structural/biophysical tendencies and can occupy functional niches. However, for each organism, protein sequences must be compatible with intracellular biomolecules and physicochemical environment, both of which vary from organism to organism. This raises the possibility that LCDs may occupy sequence spaces in select organisms that are otherwise prohibited in most organisms. Here, we report a comprehensive survey and functional analysis of LCDs in all known reference proteomes (>21k organisms), with added focus on rare and unusual types of LCDs. LCDs were classified according to both the primary amino acid and secondary amino acid in each LCD sequence, facilitating detailed comparisons of LCD class frequencies across organisms. Examination of LCD classes at different depths (i.e., domain of life, organism, protein, and per-residue levels) reveals unique facets of LCD frequencies and functions. To our surprise, all 400 LCD classes occur in nature, although some are exceptionally rare. A number of rare classes can be defined for each domain of life, with many LCD classes appearing to be eukaryote-specific. Certain LCD classes were consistently associated with identical functions across many organisms, particularly in eukaryotes. Our analysis methods enable simultaneous, direct comparison of all LCD classes between individual organisms, resulting in a proteome-scale view of differences in LCD frequencies and functions. Together, these results highlight the remarkable diversity and functional specificity of LCDs across all known life forms.

Single-molecule fluorescence multiplexing by multi-parameter spectroscopic detection of nanostructured FRET labels

Multiplexed, real-time fluorescence detection at the single-molecule level can reveal the stoichiometry, dynamics and interactions of multiple molecular species in mixtures and other complex samples. However, fluorescence-based sensing is typically limited to the detection of just 3–4 colours at a time due to low signal-to-noise ratio, high spectral overlap and the need to maintain the chemical compatibility of dyes. Here we engineered a palette of several dozen composite fluorescent labels, called FRETfluors, for multiplexed spectroscopic measurements at the single-molecule level. FRETfluors are compact nanostructures constructed from three chemical components (DNA, Cy3 and Cy5) with tunable spectroscopic properties due to variations in geometry, fluorophore attachment chemistry and DNA sequence. We demonstrate FRETfluor labelling and detection for low-concentration (<100 fM) mixtures of mRNA, dsDNA and proteins using an anti-Brownian electrokinetic trap. In addition to identifying the unique spectroscopic signature of each FRETfluor, this trap differentiates FRETfluors attached to a target from unbound FRETfluors, enabling wash-free sensing. Although usually considered an undesirable complication of fluorescence, here the inherent sensitivity of fluorophores to the local physicochemical environment provides a new design axis complementary to changing the FRET efficiency. As a result, the number of distinguishable FRETfluor labels can be combinatorically increased while chemical compatibility is maintained, expanding prospects for spectroscopic multiplexing at the single-molecule level using a minimal set of chemical building blocks.

Near-surface chemical properties of soils in the Australian Alps

Alpine soils are globally threatened and are highly vulnerable to the impacts of disturbance. In Australia, alpine soils are critically understudied and remain poorly understood. Here, the soil chemical properties of four common soil types across the Australian Alps were investigated. Soil carbon (C) and nitrogen (N) concentrations, carbon and nitrogen densities (mg cm3), carbon-to-nitrogen ratios (C:N), electrical conductivity (EC), and pH were quantified among four soils: peat soils (organosols), alpine humus soils, skeletal mountaintop soils, and disturbed soils (anthroposols). All measured soil chemical properties varied significantly among different soils, highlighting the value of understanding site-specific edaphic factors to enhance the success of restoration interventions in the Australian Alps. Large C concentrations (17.5 ± 16.6%) and C:N (30.2 ± 25.5), together with low pH (4.2 ± 0.8), EC (66.8 ± 59.6 ɥs cm−1), and N concentrations (0.55 ± 0.3%), indicate nutrient-poor soils with relatively recalcitrant C stocks across the Australian Alps, particularly in peat soils. Carbon and nitrogen densities, conversely, were greater in the alpine humus and disturbed soils, due to greater bulk densities in these soils. These results suggest that the 12,300 km2 Australian alpine bioregion appears to represent a significant terrestrial C reservoir, which may be negatively impacted by climate change. Furthermore, the findings presented suggest that active restoration of the soil physico-chemical environment alongside revegetation activities could enhance the protection of alpine soil carbon into the future.

Androgenesis and gynogenesis in tomato (&lt;I&gt;Solanum lycopersicum&lt;/I&gt; L.) &lt;I&gt;in vitro&lt;/I&gt;

Tomato (Solanum lycopersicum L.) is one of the most consumed vegetable crops worldwide. Tomato fruits are rich in vitamins, minerals, and pigments, including lycopene. The high demand and the need to enhance tomato production call for new improved cultivars and F1 hybrids.Biotechnological methods reduce the time for source material development and the labor intensity of breeding efforts. Obtaining doubled haploid plants makes it possible to fix and analyze new gene combinations faster than with conventional breeding techniques, and produce homozygous genotypes. Tomato is highly unsusceptible to haploid induction, which has been continuously studied for more than 40 years and is still of special interest. The main methods for producing haploids are based on androgenesis and gynogenesis. Androgenesis is the production of haploids from the cells of the male gametophyte, and gynogenesis from the cells of the female gametophyte.The objective was to review the research on the induction of tomato haploids based on androgenesis and gynogenesis. No standardized, efficient or reproducible protocols are currently available to produce doubled haploids of tomato. It is necessary to determine the incubation conditions, physicochemical environments, dependence of the genotype in vitro, physiological state of the donor plant, and development of the anther, which affect the reproducibility of protocols to achieve haploid induction. Anther culture for obtaining haploid tomato plants has not yielded successful results, and the studies on microspore culture were too few, so it is difficult to understand the effectiveness of this technique. The method of gynogenesis is poorly investigated, but the culture of unfertilized ovules can become a successful way to obtain tomato haploids, with more research on this subject.

Extended Battery Compatibility Consideration from an Electrolyte Perspective.

The performance of electrochemical batteries is intricately tied to the physicochemical environments established by their employed electrolytes. Traditional battery designs utilizing a single electrolyte often impose identical anodic and cathodic redox conditions, limiting the ability to optimize redox environments for both anode and cathode materials. Consequently, advancements in electrolyte technologies are pivotal for addressing these challenges and fostering the development of next-generation high-performance electrochemical batteries. This review categorizes perspectives on electrolyte technology into three key areas: additives engineering, comprehensive component analysis encompassing solvents and solutes, and the effects of concentration. By summarizing significant studies, the efficacy of electrolyte engineering is highlighted, and the review advocates for further exploration of optimized component combinations. This review primarily focuses on liquid electrolyte technologies, briefly touching upon solid-state electrolytes due to the former greater vulnerability to electrode and electrolyte interfacial effects. The ultimate goal is to generate increased awareness within the battery community regarding the holistic improvement of battery components through optimized combinations.

Increases in the soil ammonia oxidizing phylotypes and their rechange due to long-term irrigation with wastewater.

Wastewater irrigation is a common practice for agricultural systems in arid and semiarid zones, which can help to overcome water scarcity and contribute with nutrient inputs. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are key in the transformation of NH4+-N in soil and can be affected by variations in soil pH, EC, N and C content, or accumulation of pollutants, derived from wastewater irrigation. The objective of this study was to determine the changes in the ammonia oxidizing communities in agricultural soils irrigated with wastewater for different periods of time (25, 50, and 100 years), and in rainfed soils (never irrigated). The amoA gene encoding for the catalytic subunit of the ammonia monooxygenase was used as molecular reporter; it was quantified by qPCR and sequenced by high throughput sequencing, and changes in the community composition were associated with the soil physicochemical characteristics. Soils irrigated with wastewater showed up to five times more the abundance of ammonia oxidizers (based on 16S rRNA gene relative abundance and amoA gene copies) than those under rainfed agriculture. While the amoA-AOA: amoA-AOB ratio decreased from 9.8 in rainfed soils to 1.6 in soils irrigated for 100 years, indicating a favoring environment for AOB rather than AOA. Further, the community structure of both AOA and AOB changed during wastewater irrigation compared to rainfed soils, mainly due to the abundance variation of certain phylotypes. Finally, the significant correlation between soil pH and the ammonia oxidizing community structure was confirmed, mainly for AOB; being the main environmental driver of the ammonia oxidizer community. Also, a calculated toxicity index based on metals concentrations showed a correlation with AOB communities, while the content of carbon and nitrogen was more associated with AOA communities. The results indicate that wastewater irrigation influence ammonia oxidizers communities, manly by the changes in the physicochemical environment.

Physicochemical Perspective of Biological Heterogeneity.

The vast majority of chemical processes that govern our lives occur within living cells. At the core of every life process, such as gene expression or metabolism, are chemical reactions that follow the fundamental laws of chemical kinetics and thermodynamics. Understanding these reactions and the factors that govern them is particularly important for the life sciences. The physicochemical environment inside cells, which can vary between cells and organisms, significantly impacts various biochemical reactions and increases the extent of population heterogeneity. This paper discusses using physical chemistry approaches for biological studies, including methods for studying reactions inside cells and monitoring their conditions. The potential for development in this field and possible new research areas are highlighted. By applying physical chemistry methodology to biochemistry in vivo, we may gain new insights into biology, potentially leading to new ways of controlling biochemical reactions.

Microstructural characterization and inductively coupled plasma-reactive ion etching resistance of Y2O3–Y4Al2O9 composite under CF4/Ar/O2 mixed gas conditions

In the semiconductor manufacturing process, when conducting inductively coupled plasma-reactive ion etching in challenging environments, both wafers and the ceramic components comprising the chamber’s interior can be influenced by plasma attack. When ceramic components are exposed to long-term plasma environments, the eroded components must be replaced. Furthermore, non-volatile reactants can form and settle on semiconductor chips, acting as contaminants and reducing semiconductor production yield. Therefore, for semiconductor processing equipment parts to be utilized, it is necessary that they exhibit minimized generation of contaminant particles and not deviate significantly from the composition of conventionally used Al2O3 and Y2O3; part must also last long in various physicochemical etching environment. Herein, we investigate the plasma etching behavior of Y2O3–Y4Al2O9 (YAM) composites with a variety of mixing ratios under different gas fraction conditions. The investigation revealed that the etching rates and changes in surface roughness for these materials were significantly less than those of Y2O3 materials subjected to both chemical and physical etching. Microstructure analysis was conducted to demonstrate the minimization of crater formation. Mechanical properties of the composite were also analyzed. The results show that the composite can be commercialized as next-generation ceramic component in semiconductor processing equipment applications.

Diverse winter communities and biogeochemical cycling potential in the under-ice microbial plankton of a subarctic river-to-sea continuum.

Microbiomes vary over multiple timescales, with short- and long-term changes in the physico-chemical environment. However, there is a scarcity of data and understanding about the structure and functioning of aquatic ecosystems during winter relative to summer. This is especially the case for seasonally ice-covered rivers, limiting our understanding of these ecosystems that are common throughout the boreal, subpolar, and polar regions. Here, we examined the winter under-ice microbiome of a Canadian subarctic river and its entry to the sea to characterize the taxonomic and functional features of the microbial community. We found substantial diversity in both composition and functional capabilities, including the capacity to degrade complex terrestrial compounds, despite the constraints imposed by a prolonged seasonal ice-cover and near-freezing water temperatures. This study indicates the ecological complexity and importance of winter microbiomes in ice-covered rivers and the coastal marine environment that they discharge into.

Is Osteoarthritis a Vascular Disease?

Osteoarthritis (OA) is now considered as a multifaceted disease affecting various articular tissues, including cartilage, bone, synovium, and surrounding ligaments. The pathophysiology strongly implicates intricate chemical communication, primarily through cytokines, leading to the production of degradative enzymes in cartilage, inflammatory peptides in synovium, and structural changes in bone, resulting in characteristic clinical features such as joint deformities and loss of cartilage space seen on X-rays. Recent studies highlight the previously underestimated role of subchondral bone in OA, revealing its permeability to cytokines and raising questions about the influence of abnormal perfusion on OA pathophysiology, suggesting a vascular component in the disease's etiology. In essence, alterations in bone perfusion, including reduced venous outflow and intraosseous hypertension, play a crucial role in influencing the physicochemical environment of subchondral bone, impacting osteoblast cytokine expression and contributing to trabecular remodeling, changes in chondrocyte phenotype, and ultimately cartilage matrix degeneration in OA. Dynamic contrast (gadolinium) enhanced magnetic resonance imaging (DCE-MRI) was used to quantify perfusion kinetics in normal and osteoarthritic subchondral bone, demonstrating that decreased perfusion temporally precedes and spatially correlates with cartilage lesions in both young Dunkin-Hartley (D-H) guinea pigs and humans with osteoarthritis. Pharmacokinetic analysis of DCE-MRI generated data reveals decreased tracer clearance and outflow obstruction in the medial tibial plateau of osteoarthritic guinea pigs, coinciding with progressive cartilage degradation, loss of Safranin O staining, and increased expression of matrix metalloproteinases and interleukin-1. Positron emission tomographic (PET) scanning using 18F-Fluoride reveals a relationship among bone blood flow, cartilage lesions, and 18F-Fluoride influx rate in OA, highlighting the intricate relationships between decreased perfusion, altered bone metabolism, and the progression of osteoarthritis. These findings, supported by 18F-Fluoride PET data, suggest the presence of venous stasis associated with outflow obstruction, emphasizing the role of decreased subchondral bone perfusion in the pathophysiology of OA and its association with reduced osteoblast activity and advanced cartilage degeneration.

Distribution of selenium: A case study of the Drava, Danube and associated aquatic biotopes

This paper presents the results of the research on the overall distribution of selenium (Se) in various aquatic compartments (water, sediment, plankton and macrophytes) at six selected sites of the Croatian part of the Drava and Danube rivers, the connected floodplain lake and the melioration channel system carried out in two sampling periods (flooding in June and the drought period in September). In addition, the physicochemical water properties, plankton composition and biomass were analysed. Our study revealed low mean Se contents in sediments and water, indicating Se deficiency in the studied freshwater systems. The physicochemical environment, including Se distribution, was primarily influenced by hydrology rather than site-specific biogeochemical and morphological characteristics. The flooding period was characterised by higher Se content in water and higher transparency, nitrate and total nitrogen concentrations than drought conditions. At the river sites, sediment Se content was the highest during the flood period, while at all other sites, higher concentrations were found during the drought, reaching the maximum in the lake. Although Se concentrations were below the threshold for aquatic ecotoxicity, they increased in the following order: water (0.021–0.187 μg Se L−1) < sediments (0.005–0.352 mg Se kg−1) < macrophytes (0.010–0.413 mg Se kg−1) < plankton (0.044–0.518 mg Se kg−1) indicating its possible biomagnification at the bottom of the food chain. Species known for high Se accumulation potential dominated the biomass of the main plankton groups and the composition of the macrophyte community, which may provide a more sensitive and accurate steady-state compartment monitor for Se assessment in freshwater biotopes.

Effect of Bacillus amyloliquefaciens QST713 on Inter-Root Substrate Environment of Cucumber under Low-Calcium Stress

(1) Background: Low-calcium stress can have adverse effects on the rhizosphere environment of cucumber, subsequently impacting cucumber growth. However, plant-growth-promoting rhizobacteria can directly or indirectly enhance plant growth and induce plant tolerance, thereby mitigating the detrimental effects of low-calcium stress on cucumber growth. This study aims to elucidate the role of Bacillus amyloliquefaciens QST713 in the rhizosphere environment of cucumber under low-calcium stress, providing a theoretical basis for the application and promotion of Bacillus amyloliquefaciens. (2) Methods: This study used the ‘JinYou NO.4′ cucumber variety as test material, setting four treatments of CK, CK+Q, LCa, LCa+Q. We conducted measurements of plant height and stem diameter for four groups of cucumber plants: before treatment (0 d), and at 10 d, 20 d, 30 d, and 60 d after treatment. Additionally, we determined the biomass of cucumber plants under different treatments during the peak fruiting period. Inter-root matrix samples of cucumber were collected during the fruiting late period, and the physical and chemical properties and nutrient contents of the inter-root matrix of cucumber were determined, and bacterial microbial diversity and bacterial microbial communities were analysed using Illumina-MiSeq high-throughput sequencing technology. (3) Results: Low-calcium stress significantly inhibits the growth of cucumber plants. However, the application of Bacillus amyloliquefaciens QST713 effectively mitigates the inhibitory effects of low-calcium stress on cucumber growth. The application of Bacillus amyloliquefaciens QST713 was able to improve the physicochemical environment of the matrix and enhanced the absorption and utilisation of matrix nutrients in cucumber. The high-throughput sequencing analysis showed that the richness and diversity of bacterial communities and the number of bacteria decreased significantly under low-calcium stress, and increased significantly after the application of Bacillus amyloliquefaciens QST713. The composition of the dominant bacterial groups of the inter-root matrix of cucumber was basically the same among the four treatments, and the main difference was in the abundance of bacteria. The application of Bacillus amyloliquefaciens QST713 increased the relative abundance of bacteria that decreased under low-calcium stress, and decreased the relative abundance of bacteria that increased under low-calcium stress. (4) Conclusions: The results of this study elucidated the positive effects of Bacillus amyloliquefaciens QST713 on the growth and inter-root environment of cucumber under low-calcium stress, and provided a theoretical basis for in-depth research on the resistance of Bacillus amyloliquefaciens and its popularised application.

Soil food web structure coordinated by soil omnivores sustains soil multifunctionality in moderate vermicompost amended fields

Biodiversity can enhance soil multifunctionality through strengthening biotic interactions in soil food webs, but largely unknown in agroecosystems. We therefore predicted that vermicompost, serving as an organic amendment and soil health conditioner, could enhance trophic interactions among bacteria, fungi and nematodes and mediate synergies and trade-offs among soil functions, especially when substituting synthetic fertilizer was applied to soils. Soil multifunctionality was assessed from plant growth and product quality, carbon and nutrient cycling, water and climate regulation in an intensive cropping system. Pepper, tomato and spinach were cultivated in rotation annually, with substituting vermicompost as a nutrient replacement for synthetic fertilizer for 5 years. Results showed that substituting a moderate dose of vermicompost for synthetic fertilizer offered the highest soil multifunctionality by enhancing synergies among multiple functions. The vermicompost-stimulated multifunctionality was primarily attributed to the cascading effects of the complex food web structure induced by omnivorous nematode. These effects were regulated by the physicochemical environment of the vermicompost-amended soil. Notably, the multifunctional benefits degraded when higher rates of vermicompost were applied, suggesting that over-use of vermicompost combined with an inadequate amount of synthetic fertilizer could simplify soil food web structure and decrease soil functions, mainly due to the nutrient limitation and increasing harmful substances as indicated by C:N stoichiometry, heavy metals and antibiotic resistance genes. In intensive agricultural systems, finding an optimal balance of organic amendments and synthetic fertilizer that supports complex soil food web interactions is therefore crucial for promoting multiple soil functions and particularly sustaining the production of high-quality food crops.

Microbial diversity analysis of Chumathang geothermal spring, Ladakh, India.

In light of their unique and challenging environment, the high-altitude Chumathang geothermal springs in Ladakh, India, are undeniably intriguing for microbiological study. The purpose of this study was to employ a culture-independent sequencing approach to give a comprehensive characterization of the unknown bacterial and archaeal community structure, composition and networks in water and soil from the Chumathang geothermal spring. A total of 50%, and 42.86% bacterial phyla were found in the water, and soil samples respectively and this analysis also showed a total of 9.62% and 7.94% of archaeal phyla in both the samples, respectively. Further, the presence of unclassified (derived from other sequences, water: 17.31%, and soil: 19.05%) and unclassified (derived from bacteria, water: 13.46%, and soil: 12.70%) were also observed in the current metagenomics investigation. Firmicutes and Proteobacteria were the most abundant bacterial phyla in water, whereas Proteobacteria and Bacteroidetes were the most abundant bacterial phyla in geothermal soil. Crenarchaeota and Euryarchaeota dominated archeal communities in soil and water, respectively. This metagenomic study gave a detailed insight into the microbial diversity found in Chumathang geothermal spring and surrounding area, located in Ladakh, India. Surprisingly, this finding indicated the existence of geographically distinct microbial communities that were suited to various geothermal water habitats along the Himalayan Geothermal Belt. Future studies must take into account the metabolic pathways of these microbial communities that exist in these extreme environments. This will allow us to obtain a better knowledge of the microbial metabolisms that are common at these geothermal locations, which have a lot of potential for biotechnological applications. They will also enable us to establish links between the microbial community composition and the physicochemical environment of geothermal water and area.