Search Results (347)

Phosphorus (P) limitation is prevalent in terrestrial ecosystems. Plants can improve soil P availability through the exudation of organic acids and symbiotic interactions with microorganisms. However, associations between different plant functional groups and phosphorus cycling in P limited karst ecosystems remain poorly understood. To investigate this, the exudation rates of oxalic, citric and acetic acids from fine roots, the contents of carbon, nitrogen, and P in leaves and fine roots, and the contents of oxalic, citric and acetic acids, total P, available P (AP), and microbial biomass P in rhizosphere soils were measured across different plant functional groups in a karst ecosystem in southwestern China. Additionally, the activities of acid and alkaline phosphatases were also analyzed, as well as the relative abundance, community structure, diversity, and co-occurrence network patterns of arbuscular mycorrhizal fungi (AMF) and alkaline phosphatase-encoding (phoD) gene-harboring bacteria. The results showed that both the exudation rates and the contents of organic acids and AP were highest in the tree group, followed by the shrub and grass groups. The AP content of the legume group was significantly higher than that of the non-legume group. The exudation rates of oxalic acid were significantly greater than those of citric and acetic acids. AMF diversities were highest in the shrub and legume groups. The diversities of phoD-harboring bacteria decreased from the tree group to the shrub group and then to the grass group, yet there were no significant differences between the legume and non-legume groups. The communities of both AMF and phoD-harboring bacteria exhibited significant differences among these plant functional groups. The prevalent genera of phoD-harboring bacteria across all groups were Pseudomonas and Halomonas, with Halomonas being particularly prevalent in the legume group. The AMF community was dominated by Glomus, which attained its highest relative abundance in the tree and legume groups. Furthermore, the increased exudation rate and content of oxalic acid were associated with higher relative abundances of Glomus in AMF and Pseudomonas and Bacillus among phoD-harboring bacteria. Structural Equation Model (SEM) analysis demonstrated that plant-exuded organic acids, especially oxalic acid, were positively associated with P availability indirectly through their linkages with the diversity and abundance of AMF and phoD-harboring bacteria. The crucial role of oxalic acid was particularly prominent in the tree and legume groups. Our findings suggest that screening AMF and phoD-harboring bacteria with highly efficient P transformation activity and inoculating them into the rhizosphere of plants with high oxalic acid exudation could help improve plant resilience to P limitation and support sustainable restoration in karst ecosystems. Full article

The conservation of traditional villages has shifted from isolated site-by-site protection to regional collaboration, and exploring pathways for their sustainable development has become a key focus of research. Existing research still falls short in areas such as the integration of heritage value into decision-making mechanisms and the establishment of systematic conservation frameworks, leading to prominent issues of isolated conservation and homogeneous development. Taking traditional villages in Yanchuan County, China, as a case study, this research aims to establish a clustered conservation system and achieve a transition towards networked collaborative governance. The study utilised field surveys and literature review to establish a database and systematically catalogue heritage resources; it combined the Analytic Hierarchy Process (AHP) and the Delphi method to construct a value evaluation system and identify distinctive features; and it integrated cluster theory with GIS spatial analysis to construct a clustered conservation framework across three dimensions: classification and grading, symbiotic models, and the overall spatial pattern. The results indicate that: (1) the spatial distribution of villages in Yanchuan County is uneven, and the villages themselves exhibit significant homogeneity in their characteristics; (2) core characteristics include Loess culture, cave dwellings and revolutionary heritage sites, with comprehensive scores ranging from 0.4437 to 0.9116; these are classified into three protection levels, identifying five categories of villages of value. (3) Five major cluster zones were delineated based on resource and spatial characteristics. By integrating river basins and transport corridors, a comprehensive protection framework of ‘one belt, two wings, two centers and five zones’ was established, alongside three types of cluster symbiosis models, thereby achieving regional resource integration and enhancing collaborative efficiency. The cluster-based protection system proposed in this study can effectively address the challenges facing the conservation and development of traditional villages, providing a feasible solution for regional collaborative protection, and holds practical significance for cultural heritage management and sustainable development. Full article

The stable application of Partial Nitritation-Anammox (PN-A) in municipal wastewater treatment is primarily hindered by the ineffective suppression of Nitrite-Oxidizing Bacteria (NOB). This study systematically evaluated PN-A stability by comparing a Sequencing Batch Reactor (SBR) with two distinct Membrane Bioreactor (MBR) configurations. Results indicated that the SBR achieved superior performance through natural hydraulic selective washout, which efficiently eliminated NOB and fostered a robust AOB-AnAOB symbiotic biofilm. In contrast, MBRs were inherently susceptible to NOB proliferation due to their non-selective membrane retention. However, this study demonstrates that an intermittently aerated MBR (MBR-I) can effectively mitigate these disadvantages. By tailoring aeration control, the MBR-I successfully optimized the competitive kinetics for nitrite, suppressing NOB activity and achieving a robust total nitrogen removal rate (TNRR) of 76.38%. This work highlights that tailored aeration serves as a crucial synergistic strategy to bridge the inherent gap between membrane-based systems and conventional washout-driven reactors, providing a potential pathway for implementing PN-A within hybrid MBBR-MBR systems. Full article

Armillaria species hold significant ecological and economic importance and they play a vital role in the growth of traditional Chinese medicine Gastrodia elata (G. elata). In this study, we assembled and compared the mitochondrial genomes (mitogenomes) of six Armillaria mellea (Vahl) P. Kumm. (A. mellea) strains isolated from the main G. elata-producing region of Hanzhong, China. The internal transcribed spacer (ITS) sequencing confirmed that all six strains form a monophyletic clade. Their mitogenomes (120,775 to 120,839 bp) exhibit a highly conserved architecture, each containing 16 protein-coding genes (PCGs), 23 open reading frames (ORFs), 27 tRNAs, and two rRNAs. Codon usage and amino acid frequency were strikingly similar among the six strains, with a strong AT bias. In contrast, comparisons with other Armillaria species revealed marked differences in gene order, repeat structures, and selection pressures. Phylogenetic analyses based on PCGs further resolved the close relationship among the six strains while highlighting distinct molecular variation across species. On the whole, these findings demonstrate that A. mellea strains co-evolving with G. elata maintain a highly uniform mitochondrial genome architecture, suggesting strong purifying selection or recent divergence within this symbiotic population. The pronounced differences from other Armillaria species at the levels of gene arrangement and selection pressure imply that mitochondrial gene rearrangement may have accompanied species diversification in the genus. By providing the first complete mitogenomes of A. mellea from a major G. elata cultivation area, this study not only expands the genomic resources for Armillaria but also establishes a foundation for understanding how mitochondrial variation might influence fungal growth, adaptation, and symbiotic efficiency with G. elata. Full article

The majority of terrestrial plant species establish below-ground interconnections via arbuscular mycorrhizal (AM) mycelium, thereby forming extensive common mycorrhizal networks (CMNs). CMNs serve as critical infrastructure for nutrient acquisition, mediating soil nutrient capture and distribution. In nitrogen-fixing plants, phosphorus (P) transport is particularly dependent on functional CMNs. The rapid expansion in graphene oxide (GO) production and its broad application have raised significant ecological concerns, particularly regarding its potential impacts on terrestrial ecosystems. Despite these concerns, the impact of GO on P transport dynamics within legume–arbuscular mycorrhizal fungi (AMF) symbioses remains critically scarce. This study established a symbiotic system using the model nitrogen-fixing legume Medicago sativa L. and AMF. This experimental system enabled a comprehensive assessment of GO effects on rhizosphere P mobilization, plant P acquisition, CMNs architecture, fungal community composition, and expression of key P transporter genes. Our results demonstrated that high GO concentrations significantly altered rhizosphere properties, increasing pH while reducing organic acid content and alkaline phosphatase activity. Furthermore, GO exposure significantly inhibited root growth, mycorrhizal colonization rates, and plant P acquisition efficiency. Additionally, GO exposure altered AMF community composition, reduced rhizosphere microbial diversity, and suppressed P metabolism gene expression. Specifically, 0.6% GO induced significant downregulation of MsCS and GigmPT by 83.5% and 62.3%, respectively. This indicates that GO impairs plant P uptake by disrupting the core pathway involving GigmPT and MsCS, triggering P stress in M. sativa. Collectively, these findings provide compelling evidence that GO exposure disrupts legume–AMF symbiotic integrity, ultimately impairing P transport efficiency. Full article

The formulation of rhizobial bioinoculants remains a critical bottleneck for the large-scale deployment of biological nitrogen fixation in sustainable agriculture, mainly due to limitations in the stability and viability of conventional liquid products. In this study, a spray-drying-based process was developed and optimized to produce a stable and functional bioinoculant using Ensifer meliloti Rm8530, an EPS II–producing strain with enhanced stress tolerance. Strain robustness was evaluated through thermal and osmotic stress assays, together with growth performance across relevant temperature and pH ranges. Six carrier-based formulations combining polysaccharides and proteins were then tested under controlled spray-drying conditions. Process performance was assessed in terms of powder recovery, residual moisture, bacterial survival, yield, and storage stability over 16 weeks. The morphological integrity of spray-dried particles and rehydrated cells was analyzed by scanning electron microscopy. The biological functionality of selected formulations was subsequently validated in planta using alfalfa as a host model. Among the formulations tested, a mixed alginate–gum Arabic matrix showed the best overall balance between process efficiency, post-drying viability, long-term stability, and symbiotic performance. Spray-dried cells retained the ability to induce nodulation and support early plant responses under the conditions evaluated. These results demonstrate that spray drying, combined with appropriate strain selection and formulation design, constitutes a viable and scalable platform for producing stable, functional rhizobial bioinoculants. Full article

Phosphorus deficiency is a key factor limiting plant growth in desertified grasslands. Elucidating the adaptive strategies of pioneer plants that integrate root morphology and microbial interactions is crucial for understanding the natural restoration of ecosystems. This study investigated the strategies employed by Kengyilia hirsuta, a pioneer grass species in desertified grasslands, to adapt to low-phosphorus environments. By conducting sand culture experiments under varying phosphorus levels (low, optimal, and high), we focused on elucidating the synergistic adaptive mechanisms involving the root–rhizosheath system. The results showed that the rhizosheath serves as a critical micro-ecological niche for enriching arbuscular mycorrhizal fungi (AMF) and enhancing phosphatase activity. Under low-phosphorus stress, the plant strengthened root hair development and its symbiotic association with AMF, which markedly increased acid phosphatase activity and led to the highest phosphorus use efficiency. At the optimal phosphorus level, the plant developed an efficient “rhizosheath–mycorrhiza” synergistic system, characterized by high AMF colonization and spore density, facilitating optimized carbon–phosphorus exchange. Under phosphorus-sufficient conditions, the adaptive strategy transitioned towards root morphological plasticity, exemplified by increased surface area and branching. Multivariate analysis revealed that the phosphorus absorption efficiency of K. hirsuta is co-regulated by both morphological adaptation and symbiotic optimization. This study elucidates the mechanisms of nutrient stress adaptation in desertified grassland plants, providing a theoretical foundation for understanding the natural restoration processes of degraded ecosystems. Full article

The valorization of agro-industrial residues represents a strategic approach to advancing sustainability and circular bioeconomy principles in the food sector. Although bacterial cellulose (BC) production from waste substrates has been widely explored, limited attention has been given to the role of nitrogen source modulation in complex fermentation systems. This study evaluated passion fruit peel hydrolysate (PFPH), a cellulose- and hemicellulose-rich by-product, as an alternative carbon source for BC production using a symbiotic culture of bacteria and yeast (SCOBY) under static conditions. Acid hydrolysis and detoxification were performed to obtain fermentable sugars while minimizing inhibitory compounds. Different nitrogen sources and purification strategies were comparatively assessed. The highest purified BC yield (81 g L⁻¹ of culture medium) was obtained using ammonium sulfate, whereas sodium nitrate promoted greater impurity removal (77.51% mass reduction). Structural and chemical analyses (FTIR, XPS, and XRD) confirmed effective delignification, enhanced surface purity, and increased crystallinity. SEM revealed a homogeneous nanofibrillar network, and thermogravimetric analysis indicated thermal stability up to approximately 300 °C. Soil burial assays showed 26% mass loss after 42 days, demonstrating controlled biodegradation consistent with food packaging requirements. Overall, PFPH proved to be an efficient and sustainable substrate for BC biosynthesis. The modulation of nitrogen source significantly influenced both production yield and structural properties, highlighting the potential of this system for developing environmentally responsible biopolymer materials for food packaging applications. Full article

Different rhizobial strains can lead to distinct symbiotic phenotypes in alfalfa, yet molecular differences at the mature nodule stage remain unclear. Here, we analyzed 21-day post-inoculation (dpi) nodules induced by strains WE2 and WWL2. We measured nitrogenase activity (acetylene reduction assay, ARA) and performed dual RNA-seq to compare gene expression in both the alfalfa host and the rhizobia. On the host side, WE2-induced nodules showed higher expression of mature nodule marker genes (ENOD93 and leghemoglobin (Lb) genes) and higher expression of genes encoding SWEET transporters and amino acid and peptide transporters. Host differentially expressed genes were enriched in pathways related to transmembrane transport, redox and heme-related functions, and processes linked to maintaining microaerobic conditions. On the rhizobial side, WE2 nodules showed higher expression of genes involved in microaerobic respiration and nitrogen fixation (e.g., nif/fix and key respiratory chain genes), whereas WWL2 nodules showed higher expression of genes linked to transport, chemotaxis/motility, and environmental information processing. Together, these host and rhizobia expression patterns suggest coordinated differences between host pathways related to resource supply and microaerobic conditions and rhizobial expression programs for respiration and nitrogen fixation. Based on these associations, we propose a working model and provide candidate genes and pathways for functional validation and inoculant screening. Full article

The white-backed planthopper (Sogatella furcifera) is a major pest in rice-growing regions worldwide. It severely limits rice production through piercing–sucking feeding, oviposition injury, and by efficiently transmitting the Southern Rice Black-Streaked Dwarf Virus (SRBSDV). Previous studies demonstrated that the dark septate endophytic fungus Ochroconis guangxiensis strain X22 exhibits control activity against SRBSDV. To further evaluate its biocontrol potential, this study investigated the effects of the X22 strain on S. furcifera, the primary vector of SRBSDV. In this study, we established an X22–rice symbiotic system to evaluate its effects on the biological traits of S. furcifera. The results showed that, compared with a clear water treatment, the X22 strain significantly reduced the feeding amount (29.02%), egg-laying amount (12.30%), and hatching rate (11.58%) of S. furcifera. Gene expression analysis showed that the relative expression levels of the Target of Rapamycin (TOR) and vitellogenin (Vg) genes in one-day-old S. furcifera from the X22 treatment group were modestly downregulated, although no significant differences were detected compared with the control. Enzyme activity assays revealed that between 72 and 120 h post-treatment, the activities of detoxification enzymes, including carboxylesterase (CarE) and acetylcholinesterase (AChE), generally declined following X22 exposure. In contrast, the activities of protective enzymes, superoxide dismutase (SOD) and catalase (CAT), as well as certain digestive enzymes, α-amylase (α-AL) and trypsin, were induced. Conversely the activities of glutathione peroxidase (GSH-Px) and lipase (LPS) were suppressed. However, the physiological mechanisms underlying its effect on S. furcifera remain unclear. Collectively, these results demonstrate that the O. guangxiensis X22 strain inhibits S. furcifera reproduction by disrupting its physiological metabolism through multiple pathways, providing a mechanistic basis for its development as an environmentally friendly biocontrol agent. Full article

Investigations into the production of gas hydrates from marine sediments have demonstrated that commercial viability necessitates a daily gas production rate of 130,000 to 200,000 m³. However, the second-round trial production in the South China Sea yielded only 28,700 m³/day, falling short of the rule-of-thumb for economic feasibility. Given the coexistence of natural gas hydrates (NGHs) and shallow gas in the subsurface reservoirs of the South China Sea, a co-production strategy (simultaneously exploiting NGHs and shallow gas) was proposed to reduce costs and enhance production efficiency. In this study, a large-scale, three-dimensional, multi-phase, and multi-component model was established based on the NGHs–shallow gas symbiotic system in the Qiongdongnan Basin. A dual horizontal well configuration was designed to extract NGHs from the hydrate-bearing layer and natural gas from the underlying shallow gas layer. Co-production via dual horizontal wells expanded the hydrate dissociation zone from the near-wellbore region to deeper strata, particularly enhanced the dissociation of NGHs in the region between the two horizontal wells. By the 10th year of simulation, the peak and cumulative volume rate of CH₄ released from hydrate dissociation increased to 3.52 and 1.45 times under the co-production scenario, resulting in a 2.4-fold improvement in NGH recovery efficiency. Sensitivity analyses of bottom hole pressure and length of the horizontal intervals revealed that reducing bottom hole pressure significantly improved the daily and accumulative gas production from hydrate-bearing reservoirs. The length of horizontal intervals emerged as a critical factor influencing the dissociation of NGHs, whereas it had negligible impact on gas production from shallow gas reservoir with satisfied permeability. This study provides insights into optimizing the development of marine hydrate resources via integrated exploitation strategies. Full article

Achieving completeness of multipartite bacterial genomes has been a difficult task, especially in rhizobia. In this study, we performed a deep bioinformatic analysis of the newly re-sequenced genome of Rhizobium favelukesii LPU83^T. This strain was isolated from acid soils in Argentina and is capable of nodulating several leguminous plants, although it is unable to fix nitrogen efficiently in any of them. Oxford Nanopore sequencing allowed us to completely assemble the symbiotic plasmid of the strain, pRfaLPU83b, and we discovered that it harbors three intact prophages and a high density of insertion sequences (ISs). These characteristics show why it is often so difficult to complete the symbiotic plasmids of rhizobial strains and the importance of having long-read sequencing methods. Upon detailed analysis of this replicon, we identified a complete conjugation system with gene structure consistent with quorum sensing-associated systems that may have contributed to the genetic mosaic structure of the strain. Furthermore, we identified in the symbiotic plasmid of R. favelukesii LPU83^T a large proportion of the symbiotic genes previously identified as essential for Biological Nitrogen Fixation (BNF) in symbiosis with alfalfa, with a high percentage of identity with respect to those of Sinorhizobium meliloti 2011. Among the determinants related to BNF, we found genes encoding the HrrP and SapA peptidases in the LPU83 genome, previously described and related to the degradation of nodule-specific cysteine-rich peptides. These peptides are essential for bacteroid differentiation and, therefore, efficient BNF. Our results show that despite having these genes, they are not directly responsible for the inefficient BNF phenotype of LPU83. Full article

In the face of global challenges such as food insecurity, environmental degradation, and climate change, biological nitrogen fixation by rhizobia has become increasingly crucial for supporting sustainable agriculture and reducing reliance on synthetic fertilizers. Paraburkholderia phymatum STM815^T is a beta-proteobacterial rhizobium notable for its exceptionally broad host range, forming nitrogen-fixing symbioses with over 50 legume species. In this study, we identified pelB on the P. phymatum STM815^T symbiotic plasmid, which codes for a pectate lyase, whose expression is activated by the presence of pectin in the medium and during symbiosis with common bean. In the absence of pelB, P. phymatum STM815^T shows improved symbiotic performance with common bean. Plants infected with the pelB mutant developed fewer but larger nodules and exhibited a 43% increase in nitrogenase activity, suggesting that pelB in P. phymatum STM815^T may negatively affect nodulation efficiency and nitrogen fixation in common bean. Full article

Logistics parks are increasingly acting as coordination hubs in cross-border agricultural supply chains (CASCs), yet evidence on how park-enabled governance mechanisms translate into sustainability remains limited. This study examines the drivers of CASC sustainability within the context of logistics parks in Henan, China, and assesses whether the dominant park type conditions these effects. A total of 385 valid questionnaire responses were analyzed using structural equation modeling (SEM) and fuzzy-set qualitative comparative analysis (fsQCA). SEM results show that symbiotic environment cultivation is the strongest predictor of sustainability, while interface mediation efficiency and safety also significantly support cross-border circulation. The moderating role of dominant park type is supported only for the interface and sustainability link. fsQCA further identifies three equifinal configurations leading to high sustainability, indicating that strong environmental cultivation and interface efficiency can compensate for weaker elements under certain combinations. These findings clarify how logistics parks enable economic, environmental, and social value creation in CASCs and provide actionable levers for park management and policy design. Full article

Biological wastewater treatment methods are considered suitable due to several advantages, such as fast processing, low operating cost, less secondary pollution, and overall, environmentally friendly. Microalgae-based wastewater treatment has promising potential, as it not only removes pollutants but also produces valuable biomass, which can be further utilised for various applications. In such systems, microalgae bacterial consortia enhance overall treatment efficiency by promoting symbiotic relationships that improve microbial activity, environmental resilience and enhance pollutant removal efficiency. The current review provides an overview of microalgae cultivation in various wastewater streams, CO₂ sequestration and the utilisation of produced microalgal biomass for multiple applications. The manuscript also focuses on the current role of molecular tools in optimisation and the integration of artificial intelligence to enhance microalgae-based wastewater treatment and management. The manuscript highlights recent progress in wastewater treatment, resource recovery, and the contribution of microalgal biomass to the emerging bioeconomy. To address the identified research gaps and promote the practical implementation of integrated algal systems, future research should focus on the combined approach of algae-based wastewater treatment and the concurrent utilisation of algal biomass. Such research should aim to optimise cultivation conditions and operational strategies to improve nutrient removal efficiency, enhance biomass valorisation for biochar, bioplastics, or feed applications, and ensure sustainable economics. This integrated perspective will help bridge the gap between laboratory-scale studies and integration at a larger scale. Overall, this review aims to guide the effective use of microalgae for treating diverse wastewater streams while supporting efforts to mitigate greenhouse gases and reduce pollution. Full article