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We study the use of polymer gratings as light couplers into porous silicon planar waveguides for sensing applications. Experimental evidence of a guided mode in a grating-coupled porous silicon structure is presented, along with a study of its detuning due to waveguide infiltration with a chemical linker. All the measurements are in good agreement with simulations obtained by means of a Fourier modal method, where the porous silicon birefringence is considered. These results demonstrate that this system is potentially useful for chemical and biological sensing applications. [ABSTRACT FROM AUTHOR]

Carbon nanofibers are high-aspect ratio graphitic materials that have been investigated for numerous applications due to their unique physical properties such as high strength, low density, metallic conductivity, tunable morphology, chemical and environmental stabilities, as well as compatibility with organochemical modification. Surface studies are extremely important for nanomaterials because not only is the surface structurally and chemically quite different from the bulk, but its properties tend to dominate at the nanoscale due to the drastically increased surface-to-volume ratio. This review surveys recent developments in surface analysis techniques used to characterize the surface structure and chemistry of carbon nanofibers and related carbon materials. These techniques include scanning probe microscopy, infrared and electron spectroscopies, electron microscopy, ion spectrometry, temperature-programed desorption, and atom probe analysis. In addition, this article evaluates the methods used to modify the surface of carbon nanofibers in order to enhance their functionality to perform across an exceedingly diverse application space. [ABSTRACT FROM AUTHOR]

In this study, different accelerating voltages were applied in the ion-milling process to fabricate CoPt nanopillar arrays in order to investigate the influence of ion damage to magnetic properties. Nanopillar arrays fabricated at a higher accelerating voltage give a lower value of coercivity and ion damage does not broaden the switching field distribution (SFD). The ‘edge damage’ model was employed in micromagnetic simulations to investigate the reversal mechanism and SFD. The results shows that the edge damage can change the switching mode from coherent rotation to nucleation followed by rapid domain wall motion, and the broad SFD mainly comes from the intrinsic anisotropy distribution, rather than size distribution. In addition, the angle dependence of the switching field measurement shows that nanopillars with damaged edges have Stoner–Wohlfarth behaviour, which indicates that fitting the Stoner–Wohlfarth curve does not necessarily mean coherent rotation. It is the comparison between the field for domain wall motion and the nucleation field that determines the location of angle dependence curves. [ABSTRACT FROM AUTHOR]

The RUBY reporter system has demonstrated great potential as a visible marker to monitor gene expression in both transiently and stably transformed plant tissues. Ectopic expression of the RUBY reporter leads to bright red pigmentation in plant tissues that do not naturally accumulate betalain. Unlike traditional visual markers such as b-glucuronidase (GUS), luciferase (LUC), and various fluorescent proteins, the RUBY reporter system does not require sample sacrifice or special equipment for visualizing the gene expression. However, a robust quantitative analysis method for betalain content has been lacking, limiting accurate comparative analyses. In this work, we present a simple and rapid protocol for quantitative evaluation of RUBY expression in transgenic plant tissues. Using this method, we demonstrate that differential RUBY expression can be quantified in transiently transformed leaf tissues, such as agroinfiltrated Nicotiana benthamiana leaves, and in stable transgenic maize tissues, including seeds, leaves, and roots. We found that grinding fresh tissues with a hand grinder and plastic pestle, without the use of liquid nitrogen, is an effective method for rapid betalain extraction. Betalain contents estimated by spectrophotometric and High-Performance Liquid Chromatography (HPLC) analyses were highly consistent, validating that our rapid betalain extraction and quantification method is suitable for comparative analysis. In addition, betalain content was strongly correlated with RUBY expression level in agroinfiltrated N. benthamiana leaves, suggesting that our method can be useful for monitoring transient transformation efficiency in plants. Using our rapid protocol, we quantified varying levels of betalain pigment in N. benthamiana leaves, ranging from 110 to 1066 mg/kg of tissue, and in maize samples, ranging from 15.3 to 1028.7 mg/kg of tissue. This method is expected to streamline comparative studies in plants, providing valuable insights into the effectiveness of various promoters, enhancers, or other regulatory elements used in transgenic constructs. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) free-standing nanostructures based on electron-beam lithography (EBL) have potential applications in many fields with extremely high patterning resolution and design flexibility with direct writing. In numerous EBL processes designed for the creation of 3D structures, the multilayer resist system is pivotal due to its adaptability in design. Nevertheless, the compatibility of solvents between different layers of resists often restricts the variety of feasible multilayer combinations. This paper introduces an innovative approach to address the bottleneck issue by presenting a novel concept of multilayer resist dry stacking, which is facilitated by a near-zero adhesion strategy. The poly(methyl methacrylate) (PMMA) film is stacked onto the hydrogen silsesquioxane (HSQ) resist using a dry peel and release technique, effectively circumventing the issue of HSQ solubilization by PMMA solvents typically encountered during conventional spin-coating procedures. Simultaneously, a dry lift-off technique can be implemented by eschewing the use of organic solvents during the wet process. This pioneering method enables the fabrication of high-resolution 3D free-standing plasmonic nanostructures and intricate 3D free-standing nanostructures. Finally, this study presents a compelling proof of concept, showcasing the integration of 3D free-standing nanostructures, fabricated via the described technique, into the realm of Fabry–Perot cavity resonators, thereby highlighting their potential for practical applications. This approach is a promising candidate for arbitrary 3D free-standing nanostructure fabrication, which has potential applications in nanoplasmonics, nanoelectronics, and nanophotonics. [ABSTRACT FROM AUTHOR]

The assembly and function of microbial communities depends on many factors including the local environment and the metabolic properties of the colonizing organisms. Chemical communications or other secreted factors also play a role and are used by different microbial strains both cooperatively and competitively. The spectrum of microbial secretions have various effects on the microbe's respective hosts, both positive and negative. Thus, characterizing the roles of microbial community members and their secretions can yield key mechanistic insights into microbiome function and can lead to new intervention strategies. Focusing on the simple, yet important functional impact of toxicity, we quantify supernatant dosage responses with image data and examine the morphological effects of microbial secretions on skin-associated host cells. Since the diversity of microbial communities, coupled with the multiplicity of host tissues requires scalable methods, we develop and demonstrate a microfluidic device that enables high-content screening of microbial secretion effects on adherent cell types., (© 2023 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals LLC.)

Diverse and complex microbiomes are found in virtually every environment on Earth. Bacteria and fungi often co-dominate environmental microbiomes, and there is growing recognition that bacterial-fungal interactions (BFI) have significant impacts on the functioning of their associated microbiomes, environments, and hosts. Investigating BFI in vitro remains a challenge, particularly when attempting to examine interactions at multiple scales of system complexity. Fabricated devices can provide control over both biotic composition and abiotic factors within an experiment to enable the characterization of diverse BFI phenotypes such as modulation of growth rate, production of biomolecules, and alterations to physical movements. Engineered devices ranging from microfluidic chips to simulated rhizosphere systems have been and will continue to be invaluable to BFI research, and it is anticipated that such devices will continue to be developed for diverse applications in the field. This will allow researchers to address specific questions regarding the nature of BFI and how they impact larger microbiome and environmental processes such as biogeochemical cycles, plant productivity, and overall ecosystem resilience. Devices that are currently used for experimental investigations of bacteria, fungi, and BFI are discussed herein along with some of the associated challenges and several recommendations for future device design and applications. [ABSTRACT FROM AUTHOR]

Nanoparticles play a crucial role in the field of nanotechnology, offering different properties due to their surface area attributed to their small size. Among them, silver nanoparticles (AgNPs) have attracted significant attention due to their antimicrobial properties, with applications that date back from ancient medicinal practices to contemporary commercial products containing ions or silver nanoparticles. AgNPs possess broad-spectrum biocidal potential against bacteria, fungi, viruses, and Mycobacterium, in addition to exhibiting synergistic effects when combined with certain antibiotics. The mechanisms underlying its antimicrobial action include the generation of oxygen-reactive species, damage to DNA, rupture of bacterial cell membranes and inhibition of protein synthesis. Recent studies have highlighted the effectiveness of AgNPs against various clinically relevant bacterial strains through their potential to combat antibioticresistant pathogens. This review investigates the proteomic mechanisms by which AgNPs exert their antimicrobial effects, with a special focus on their activity against planktonic bacteria and in biofilms. Furthermore, it discusses the biomedical applications of AgNPs and their potential non-preparation of antibiotic formulations, also addressing the issue of resistance to antibiotics. [ABSTRACT FROM AUTHOR]

Introduction: Variability in microbial residues within soil aggregates are becoming progressively essential to the nutritive and sustainability of soils, and are therefore broadly regarded as an indispensable part of soil organic matter. It is unexplored how the widespread implementation of microbial fertilisers in agricultural production impacts soil organic nutrients, in particular the microbial residue fraction. Methods: We performed a three-year field experiment to verify the distinct impacts of microbial and organic fertilizers on carbon accumulation in soil microbial leftovers among aggregate fractions. Results: Microbial residual carbon was shown to decrease insignificantly during the application of microbial fertilizer and to rise marginally afterwards with the utilization of organic fertilizer. However, the combined effects of the two fertilizers had substantial impacts on the accumulation of microbial residual carbon. Changes in the structure of the fungi and bacteria shown in this study have implications for the short-term potential of microbial fertilizer shortages to permanent soil carbon sequestration. Additionally, our findings revealed variations in microbial residue accumulation across the microbial fertilizers, with Azotobacter chroococcum fertilizer being preferable to Bacillus mucilaginosus fertilizer due to its higher efficiency. In this scenario of nutrient addition, fungal residues may serve as the primary binding component or focal point for the production of new microaggregates, since the quantity of SOC provided by fungal residues increased while that supplied by bacterial residues decreased. Discussion: Our findings collectively suggested that the mechanisms behind the observed bacterial and fungal MRC (microbial residue carbon) responses to microbial fertilizer or organic fertilizer in bamboo forest soils are likely to be distinct. The application of microbial fertilizers for a limited duration led to a decline soil stable carbon pool, potentially influencing the regulation of soil nutrients in such hilly bamboo forests. [ABSTRACT FROM AUTHOR]

Due to the dissimilarity among different producing layers, the influences of inter-layer interference on the production performance of a multi-layer gas reservoir are possible. However, systematic studies of inter-layer interference for tight gas reservoirs are really limited, especially for those reservoirs in the presence of water. In this work, five types of possible inter-layer interferences, including both absence and presence of water, are identified for commingled production of tight gas reservoirs. Subsequently, a series of reservoir-scale and pore-scale numerical simulations are conducted to quantify the degree of influence of each type of interference. Consistent field evidence from the Yan'an tight gas reservoir (Ordos Basin, China) is found to support the simulation results. Additionally, suggestions are proposed to mitigate the potential inter-layer interferences. The results indicate that, in the absence of water, commingled production is favorable in two situations: when there is a difference in physical properties and when there is a difference in the pressure system of each layer. For reservoirs with a multi-pressure system, the backflow phenomenon, which significantly influences the production performance, only occurs under extreme conditions (such as very low production rates or well shut-in periods). When water is introduced into the multi-layer system, inter-layer interference becomes nearly inevitable. Perforating both the gas-rich layer and water-rich layer for commingled production is not desirable, as it can trigger water invasion from the water-rich layer into the gas-rich layer. The gas-rich layer might also be interfered with by water from the neighboring unperforated water-rich layer, where the water might break the barrier (eg weak joint surface, cement in fractures) between the two layers and migrate into the gas-rich layer. Additionally, the gas-rich layer could possibly be interfered with by water that accumulates at the bottom of the wellbore due to gravitational differentiation during shut-in operations. [ABSTRACT FROM AUTHOR]

Shale oil is stored in nanoscale shale reservoirs. To explore enhanced recovery, it is essential to characterize the flow of hydrocarbons in nanopores. Molecular dynamics simulation is required for high-precision and high-cost experiments related to nanoscale pores. This technology is crucial for studying the kinetic characteristics of substances at the micro- and nanoscale and has become an important research method in the field of micro-mechanism research of shale oil extraction. This paper presents the principles and methods of molecular dynamics simulation technology, summarizes common molecular models and applicable force fields for simulating shale oil flow and enhanced recovery studies, and analyzes relevant physical parameters characterizing the distribution and kinetic properties of shale oil in nanopores. The physical parameters analyzed include interaction energy, density distribution, radial distribution function, mean-square displacement, and diffusion coefficient. This text describes how molecular dynamics simulation explains the mechanism of oil driving in CO2 injection technology and the factors that influence it. It also summarizes the advantages and disadvantages of molecular dynamics simulation in CO2 injection for enhanced recovery of shale oil. Furthermore, it presents the development trend of molecular dynamics simulation in shale reservoirs. The aim is to provide theoretical support for the development of unconventional oil and gas. [ABSTRACT FROM AUTHOR]

Marine bacteria have been targeted by industry and pharmaceutics as genetic resources for highly active enzymes or novel lead compounds. Although numerous techniques have been introduced to isolate useful bacteria from the environment, we are still highly dependent on the conventional direct cultivation method to attain pure cultures. However, efficient bacterial isolation is hindered by several factors, including the presence of impurities. In this work, to demonstrate the significance of removing impurities and their impact on bacterial isolation, we employed two approaches: dielectrophoresis (DEP) and fluorescent D-amino acids (FDAA). We successfully attained clean bacterial fractions applicable for downstream processing using these approaches, uniquely designed to identify bacteria based on their characteristics and features. The diversity of bacteria attained by both approaches was investigated using 16S rRNA sequencing and compared to that attained by the standard differential centrifugation method. In addition, the viability of the isolates was also determined via direct cultivation. As a result, the separation of bacteria from impurities allowed for the identification of novel and useful bacteria unique to each approach. Successful cultivation also suggested that both approaches were applicable for attaining viable bacteria. In conclusion, removing impurities to attain clean bacterial fractions promotes the isolation of novel bacteria and thus could aid in the successful isolation of useful bacteria within complex environmental samples. [ABSTRACT FROM AUTHOR]

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Specific antibodies are widely used in the biomedical field. Current screening methods for specific antibodies mainly involve hybridoma technology and antibody engineering techniques. However, these technologies suffer from tedious screening processes, long preparation periods, high costs, low efficiency, and a degree of automation, which have become a bottleneck for the screening of specific antibodies. To overcome these difficulties, microfluidics has been developed as a promising technology for high-throughput screening and high purity of antibody. In this review, we provide an overview of the recent advances in microfluidic applications for specific antibody screening. In particular, hybridoma technology and four antibody engineering techniques (including phage display, single B cell antibody screening, antibody expression, and cell-free protein synthesis) based on microfluidics have been introduced, challenges, and the future outlook of these technologies are also discussed., (© 2022 Wiley-VCH GmbH.)

Viruses, with an estimated abundance of 1031 on Earth, are an important component of soil ecosystems. As obligate parasites that entirely depend on hosts for reproduction and survival, viruses have been linked to microbial community diversity and metabolic activities in soil. Emerging evidence indicates that soil viruses influence a broad-spectrum of processes that sustain soil biodiversity, biogeochemical cycling, fertility, and plant health. Research on soil viruses is in its early stages. Even observational assessments of viral ecology such as abundance, diversity, distribution, life strategies, ecological relevance, and functions, are only just beginning to be revealed. In this review, we summarize the state of knowledge concerning the potential function(s) of soil viruses and how they likely influence microbial community composition, nutrient cycles, and carbon dynamics for example. As major drivers of microbial mortality and functioning across a wide range of spatial and temporal scales, soil viruses appear to be key regulators of cellular metabolism and microbial community properties and as well as biogeochemical processes critical to ecosystem function. We conclude that soil viruses are an indispensable component of soil ecology demanding further investigation. Defining abiotic interactions of viruses within the soil environment, revealing the virus-host interaction networks, and elucidating the roles of soil viruses in carbon and nutrient cycling are but a few of the many aspects of soil viral ecology worthy of future investigation. A more complete view of viral participation in soil food webs in the face of a changing climate will lead to improved management of soil ecosystem services and environmental sustainability. [ABSTRACT FROM AUTHOR]

As one of the main hydrogen production devices, the performance of the proton exchange membrane electrolytic cell (PEMEC) is directly related to the geometric design of the flow channel. In this paper, a new orthogonally sinusoidal channel with periodic fluctuations in both horizontal and vertical planes is proposed. The effects of amplitude and angular frequency in two orthogonally sinusoidal channels with the same or opposite frequency on PEMEC performance are studied by numerical simulation. The results show that the spatial amplitude and angular frequency effectively improve the electrochemical performance and mass transfer performance of PEMEC. Compared with Case 1-1, the polarization performance of Case 7-2 is increased by 16.39% because of the largest spatial amplitude. The oxygen content at 40 mm away from the inlet in the diffusion layer is also decreased by 42.63%. The horizontal angular frequency can increase the hydrogen content by 11.07% at most in Case 5-2. However, the increase in vertical angle frequency will inhibit the oxygen removal on the anode side. The sinusoidal flow channel in orthogonal spaces will provide a particular reference for the design of PEMEC in the future. [ABSTRACT FROM AUTHOR]

Over the past 45 years, the discovery of surface-enhanced Raman scattering (SERS), which enhances the Raman scattering of molecules absorbed on or near nanostructured metal surfaces, has brought significant potential as a powerful spectroscopic and analytical technique for various fields of ultrasensitive sensing applications. In preference to rigid substrates, recent advances in the development of flexible SERS sensors have enabled the fulfillment of practical on-site sensing and diagnostic applications with rapid and efficient sampling approaches. In this review, we summarize and discuss the most recent developments in flexible SERS substrates for on-site sensing and diagnosis over the past 4 years. We highlight the three main categories of flexible SERS sensors based on their sampling methods, including drop-and-dry, collection/swabbing, and wearable/attachable approaches. The use of substrate materials and the design of sensing platforms for sampling regarding various targets are reviewed. Finally, we discuss the challenges and perspectives of flexible SERS sensors for future developments. [ABSTRACT FROM AUTHOR]

Bacteria identification and counting at the small population scale is important to many applications in the food safety industry, the diagnostics of infectious diseases and the study and discovery of novel antimicrobial compounds. There is still a lack of easy to implement, fast and accurate methods to count populations of motile cells at the single-cell level. Here, we report a label-free method to count and localize bacterial cells freely swimming in microfluidic anchored picolitre droplets. We used the object detection oriented YOLOv4 deep learning framework for cell detection from bright-field images obtained with an automated Z-stack setup. The neural network was trained to recognize Escherichia coli cell morphology with an average precision of approximately 84%. This allowed us to accurately identify individual cell division events, enabling the study of stochastic bacterial growth starting from initial populations as low as one cell. This work also demonstrates the ability to study single cell lysis in the presence of T7 lytic bacterial viruses (phages). The high precision in cell numbers facilitated the visualization of bacteria-phage interactions over timescale of hours, paving the way towards deciphering phage life cycles in confined environments. [ABSTRACT FROM AUTHOR]

Plants possess myriad defenses against their herbivores, including constitutive and inducible chemical compounds and regrowth strategies known as tolerance. Recent studies have shown that plant tolerance and resistance are positively associated given they are co‐localized in the same molecular pathway, the oxidative pentose phosphate pathway. However, given that both defensive strategies utilize carbon skeletons from a shared resource pool in the oxidative pentose phosphate pathway there are likely costs in maintaining both resistance‐tolerance strategies. Here we investigate fitness costs in maintaining both strategies by utilizing a double knockout of cyp79B2 and cyp79B3, key enzymes in the biosynthetic process of indole glucosinolates, which convert tryptophan to indole‐3‐acetaldoxime (IAOx) and is further used to produce indole glucosinolates. These mutant plants are devoid of any indole glucosinolates thus reducing plant resistance. Results show that knocking out indole glucosinolate production and thus one of the resistance pathways leads to an approximate 94% increase in fitness compensation shifting the undercompensating wild‐type Columbia‐0 to an overcompensating genotype following damage. We discuss the potential mechanistic basis for the observed patterns. [ABSTRACT FROM AUTHOR]

Tissue penetrating microelectrode neural probes can record electrophysiological brain signals at resolutions down to single neurons, making them invaluable tools for neuroscience research and Brain-Computer-Interfaces (BCIs). The known gradual decrease of their electrical interfacing performances in chronic settings, however, remains a major challenge. A key factor leading to such decay is Foreign Body Reaction (FBR), which is the cascade of biological responses that occurs in the brain in the presence of a tissue damaging artificial device. Interestingly, the recent adoption of Complementary Metal Oxide Semiconductor (CMOS) technology to realize implantable neural probes capable of monitoring hundreds to thousands of neurons simultaneously, may open new opportunities to face the FBR challenge. Indeed, this shift from passive Micro Electro-Mechanical Systems (MEMS) to active CMOS neural probe technologies creates important, yet unexplored, opportunities to tune probe features such as the mechanical properties of the probe, its layout, size, and surface physicochemical properties, to minimize tissue damage and consequently FBR. Here, we will first review relevant literature on FBR to provide a better understanding of the processes and sources underlying this tissue response. Methods to assess FBR will be described, including conventional approaches based on the imaging of biomarkers, and more recent transcriptomics technologies. Then, we will consider emerging opportunities oered by the features of CMOS probes. Finally, we will describe a prototypical neural probe that may meet the needs for advancing clinical BCIs, and we propose axial insertion force as a potential metric to assess the influence of probe features on acute tissue damage and to control the implantation procedure to minimize iatrogenic injury and subsequent FBR. [ABSTRACT FROM AUTHOR]

Harvesting corn stover can negatively impact soil chemical and physical properties, but less is known regarding its effects on soil microbiology. We evaluated the impact of corn (Zea mays L.) stover removal level (SRL) on soil microbial biomass (MB) and extracellular enzyme activities (EEAs) in irrigated, continuous corn located in eastern Nebraska. Soil fatty acid‐methyl esters (FAMEs) and EEA of eight soil enzymes were measured over 2 years, 0‐ to 20‐cm soil depth, under conventional disk tillage (CT) and no‐till (NT) under three SRLs. Soil chemical properties were measured as explanatory variables for changes in soil microbial communities and their enzymatic potential. Potential EEA of all enzymes decreased with stover removal and tillage. Soil bacterial biomass (BB) and fungal biomass (FB) decreased with SRL, while mycorrhizal biomass was unresponsive. Impacts of tillage on MB groups varied by year; however, FB was consistently higher under CT. At all growth stages, NT with all stover retained, a "soil conservation target" had distinct soil enzyme and bacterial FAME profiles compared to CT across all SRLs and to NT under high and sometimes moderate SRLs. Principal component analysis of soil properties was dominated by SRL with EEAs, BB, soil organic matter (SOM), water‐extractable carbon, and H3A‐extractable potassium being positively correlated to stover retention. Reduced input of microbial substrates also led to a loss of fine particulate organic matter, an indicator correlated to stable macroaggregation. Because NT partially ameliorated the negative impact of stover removal on BB, SOM fractions, and soil enzymes critical to nutrient cycling, pairing NT with stover removal may be more sustainable in the long term. Core Ideas: Harvesting stover decreases soil MB and potential enzyme activities under both NT and CT.Stover removal strongly impacts normalized enzyme activities under NT.Both tillage and stover removal strongly impact soil bacterial community structure.Reduced MB, fPOM, and altered bacterial community structure signal loss of microbial habitat.NT marginally mitigates the impact of harvesting stover on surface soil (0‐ to 20‐cm depth). [ABSTRACT FROM AUTHOR]

Soil microbiota of the rhizosphere are an important extension of the plant phenotype because they impact the health and fitness of host plants. The composition of these communities is expected to differ among host plants due to influence by host genotype. Given that many plant populations exhibit fine‐scale genetic structure (SGS), associated microbial communities may also exhibit SGS. In this study, we tested this hypothesis using Chamaecrista fasciculata, a legume species that has previously been determined to have significant SGS. We collected genetic data from prokaryotic and fungal rhizosphere communities in association with 70 plants in an area of ~400 square meters to investigate the presence of SGS in microbial communities. Bacteria of Acidobacteria, Protobacteria, and Bacteroidetes and fungi of Basidiomycota, Ascomycota, and Mortierellomycota were dominant members of the rhizosphere. Although microbial alpha diversity did not differ significantly among plants hosts, we detected significant compositional differences among the microbial communities as well as isolation by distance. The strongest factor associated with microbial distance was genetic distance of the other microbial community, followed by geographic distance, but there was not a significant association with plant genetic distance for either microbial community. This study further demonstrates the strong potential for spatial structuring of soil microbial communities at the smallest spatial scales and provides further insight into the complexity of factors that influence microbial composition in soils and in association with host plants. [ABSTRACT FROM AUTHOR]

Soil microbial traits and functions play a central role in soil organic carbon (SOC) dynamics. However, at the macroscale (regional to global) it is still unresolved whether (i) specific environmental attributes (e.g., climate, geology, soil types) or (ii) microbial community composition drive key microbial traits and functions directly. To address this knowledge gap, we used 33 grassland topsoils (0-10 cm) from a geoclimatic gradient in Chile. First, we incubated the soils for 1 week in favorable standardized conditions and quantified a wide range of soil microbial traits and functions such as microbial biomass carbon (MBC), enzyme kinetics, microbial respiration, growth rates as well as carbon use efficiency (CUE). Second, we characterized climatic and physicochemical properties as well as bacterial and fungal community composition of the soils. We then applied regression analysis to investigate how strongly the measured microbial traits and functions were linked with the environmental setting versus microbial community composition. We show that environmental attributes (predominantly the amount of soil organic matter) determined patterns of MBC along the gradient, which in turn explained microbial respiration and growth rates. However, respiration and growth normalized for MBC (i.e., specific respiration and growth) were more linked to microbial community composition than environmental attributes. Notably, both specific respiration and growth followed distinct trends and were related to different parts of the microbial community, which in turn resulted in strong effects on microbial CUE. We conclude that even at the macroscale, CUE is the result of physiologically decoupled aspects of microbial metabolism, which in turn is partially determined by microbial community composition. The environmental setting and microbial community composition affect different microbial traits and functions, and therefore both factors need to be considered in the context of macroscale SOC dynamics., (© 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd.)

The red imported fire ants (RIFA, Solenopsis invicta) have become a well-known invasive species that poses significant ecological and economic threats globally. As of recent times, the geographic scope of its invasion in China is rapidly expanding, thereby aggravating the extent and severity of its detrimental effects. The importance of soil microorganisms for maintaining soil health and ecosystem function has been widely acknowledged. However, the negative impact of RIFAs on soil microbial communities and their functions has not yet been fully understood. In this study, we sequenced the V3-V4 variable region of the bacterial 16S rRNA gene in soil samples collected from three types of RIFA nests to investigate the impact of RIFA invasion on soil microbial diversity and composition. The results of alpha diversity analysis showed that the normal soil without nests of RIFAs exhibited the highest level of diversity, followed by the soil samples from RIFA-invaded nests and abandoned nests. Taxonomy and biological function annotation analyses revealed significant differences in microbial community structure and function among the different samples. Our findings demonstrate that RIFA invasion can significantly alter soil microbial community composition, which could ultimately affect ecosystem function. Therefore, effective management strategies are urgently needed to mitigate the negative impact of invasive species on native ecosystems. [ABSTRACT FROM AUTHOR]