Sphingomonas: from diversity and genomics to functional role in environmental remediation and plant growth

Carposphere microbiota alters grape volatiles and shapes the wine grape typicality

While specific environments are known to shape plant metabolomes and the makeup of their associated microbiome, it is as yet unclear whether carposphere microbiota contribute to the characteristics of grape fruit flavor of a particular wine region. Here, carposphere microbiomes and berry transcriptomes and metabolomes of three grape cultivars growing at six geographic sites were analyzed. The composition of the carposphere microbiome was determined mainly by environmental conditions, rather than grape genotype. Bacterial microbiota likely contributed to grape volatile profiles. Particularly, candidate operational taxonomic units (OTUs) in genus Sphingomonas were highly correlated with grape C6 aldehyde volatiles (also called green leaf volatiles, GLVs), which contribute to a fresh taste. Furthermore, a core set of expressed genes was enriched in lipid metabolism, which is responsible for bacterial colonization and C6 aldehyde volatile synthesis activation. Finally, a similar grape volatile profile was observed after inoculating the berry skin of two grape cultivars with Sphingomonas sp., thus providing evidence for the hypothetical microbe-metabolite relationship. These results provide novel insight into how the environment-microbiome-plant quality (E × Mi × Q) interaction may shape berry flavor and thereby typicality, serving as a foundation for decision-making in vineyard microbial management.

Isolation and characterization of a bioactive compound from Sphingomonas sanguinis DM with cytotoxic and molecular docking analysis

Datura metel, a common plant in the Solanaceae family, is known for its valuable medicinal properties. The metabolites created by its rhizosphere bacterium, Sphingomonas sanguinis DM, have garnered interest for their potential biological effects. This study will discuss the steps involved in fermenting and processing a bacterial strain to extract potent secondary metabolites. The ethyl acetate extract of the propagated strain was subjected to fractionation and purification through various chromatographic techniques. The purified compound was characterized through multiple spectroscopic methods for structure elucidation, including UV, MS, 1D, and 2D-NMR. Its cytotoxic activity was assessed on malignant skin cells (A-431) using the MTT test compared with normal melanocytes (HFB 4). Furthermore, A-431 cells were double-stained with PI and annexin V-FITC and analyzed by flow cytometry to detect Apoptosis. Molecular investigations include PCR screening to detect genes related to the biosynthesis of bioactive metabolites, such as NRPS and lipopeptide ItuD genes. A prospective effective strategy to overcome tumor plasticity in melanoma is to target the Wnt signaling pathways. Molecular docking studies were conducted in the different proteins (Fz4-CRD, LRP6, GSK3β) of the Wnt signaling pathway and Protein Kinase B/Akt for the isolated compound to investigate the possible pathway to inhibit melanoma. Sphingomonas sanguinis DM produced bis (2-methylheptyl) benzene-1,4-dicarboxylate isolated for the first time from a natural source. It was cytotoxic against the A-431 human skin carcinoma cell line (IC50 = 191.61 µg/mL) but less effective against HFB 4 human normal melanocytes (IC50 = 416.23 µg/mL; selectivity index = 2.17). The A-431 cells showed a significant increase in early Apoptosis and a moderate rise in late Apoptosis. PCR amplification confirmed genes encoding A domain and Iturin A. Bacterial sequences are available in NCBI GenBank with accession codes OR597597 and OR597598. Consequently, Sphingomonas sanguinis DM synthesized a cytotoxic natural terephthalate diester derivative, along with the host specificity of the strain.

Plant nickel-exclusion versus hyperaccumulation: a microbial perspective

BACKGROUND

In New Caledonia, nearly 2000 plant species grow on ultramafic substrates, which contain prominent levels of heavy metals and are deficient in essential plant nutrients. To colonize these habitats, such plants, known as metallophytes, have developed various adaptive behaviors towards metals (exclusion, tolerance, or hyperaccumulation). Ultramafic substrates also host many unique microorganisms, which are adapted to metallic environments and capable of boosting plant growth while assisting plants in acquiring essential micronutrients. Hence, plant-microbiota interactions play a key role in adapting to environmental stress. Here, we hypothesised that microbial associations in the different aboveground and underground compartments of metallophytes could be associated to their metal hyperaccumulation or exclusion phenotypes. This hypothesis was tested using a systematic comparative metabarcoding approach on the different compartments of two New Caledonian metallophytes belonging to the same genus and living in sympatry on ultramafic substrates: Psychotria gabriellae, a nickel-hyperaccumulator (Ni-HA), and Psychotria semperflorens, the related non-accumulator (nA) species.

RESULTS

The study of the diversity and specificity of fungal amplicon sequence variants (ASVs) reveals a structuring of fungal communities at both the plant phenotype and compartment levels. In contrast, the structure of bacterial communities was primarily shaped by the belowground compartments. Additionally, we observed a lower diversity in the bacterial communities of the aboveground compartments of each species. For each plant species, we highlighted a distinct global microbial signature (biomarkers), as well as compartment-specific microbial associations.

CONCLUSION

To our knowledge, this study is the first to systematically compare the microbiomes associated with different compartments of New Caledonian metallophyte species growing on the same substrate and under identical environmental conditions but exhibiting different adaptive phenotypes. Our results reveal distinct microbial biomarkers between the Ni-hyperaccumulator and non-accumulator Psychotria species. Most of the highlighted biomarkers are abundant in various plants under metal stress and may contribute to improving the phytoextraction or phytostabilization processes. They are also known to tolerate heavy metals and enhance metal stress tolerance in plants. The present findings highlight that the microbial perspective is essential for better understanding the mechanisms of hyperaccumulation and exclusion at the whole-plant level. Video Abstract.

Effects of herbicide mixtures on the diversity and composition of microbial community and nitrogen cycling function on agricultural soil: A field experiment in Northeast China

Herbicide mixtures application is a widespread and effective practice in modern agriculture; however, a knowledge gap exists regarding the potential ecotoxicological effects of herbicide mixtures in agricultural systems. Here, the effects of various doses of herbicide mixtures (atrazine, nicosulfuron, and mesotrione) under different varieties of maize cultivation on the structure and function of microbial communities and soil chemical parameters were clarified through field experiments. The results showed that the application of herbicide mixtures increased the bacterial and fungal community alpha diversity at jointing and maturity, indicating a prolonged effect of the herbicide mixtures. Moreover, herbicide mixtures alter the composition of bacterial and fungal communities, with sensitive taxa suppressed and herbicide-tolerant taxa enriched. The herbicide mixtures significantly reduced the abundances of Bacillus even at lower doses, but Penicillum was enriched. FAPROTAX analysis and quantitative PCR (qPCR) results showed that herbicide mixtures inhibited the soil nitrogen-cycle process and related genes AOA-amoA, AOB-amoA, and nifH at maize seedling stage. Moreover, network analysis showed that low concentrations of the herbicide mixtures increased bacterial interactions while high concentrations inhibited them, which indicated that the network complexity may be herbicide concentration dependent. A synthetic community (SynCom) consisting of six bacterial strains was established for the biodegradation of the herbicide mixtures based on the analysis of the bacterial network, which resulted in an increase in the degradation efficiency of nicosulfuron by 15.90%. Moreover, potted maize experiment showed that the addition of the SynCom alleviated the toxic effects of herbicide mixtures on the plants. In summary, this study provides a comprehensive perspective for assessing the ecological risk at taxonomic and functional levels and the biodegradation approach of herbicide mixtures residue on agricultural soils in Northeastern China.

Microbial welan gum production, chemistry and applications: A review

Welan gum, an extracellular polysaccharide produced by the Sphingomonas sp., has attracted considerable interest due to its distinctive properties and promising applications in adhesion, thickening, suspension, emulsification, stabilization, lubrication, and film formation. However, several unresolved issues related to welan gum, particularly its low biosynthesis efficiency, have hindered its widespread industrial application. This review first aims to provide a comprehensive overview of welan gum, focusing on its structure and development, the production strains, and biosynthesis pathways. To facilitate the industrial application of welan gum, we further summarize strategies, including optimizing fermentation conditions and engineering production strains to enhance yield, and discuss methods for the recovery and purification of welan gum based on existing literature. Then, we explore the relationship between the modification, structure, and properties of welan gum, emphasizing how these factors can enhance its functionality and application value. Furthermore, the review elucidates the behavior of welan gum in aqueous solutions, examining the impacts of pH, cations, temperature variations, and various additives. In conclusion, we provide a concise summary of the current applications of welan gum and present key research areas that warrant further investigation to advance its use in industry.

Dynamics of chemical profile and microbial community in 3 consecutive years reveal Rhodococcus and Apiotrichum are potential microbes contributing to quality formation of Guang Chenpi

Currently, there remains a debate regarding the functional microorganisms responsible for the quality formation of Guang Chenpi (GCP). Thus, the metabolite profiles and microbial diversity of GCP samples subjected to natural treatment versus those sterilized via electron beam irradiation were investigated over a three-year period. It was found the main constituents of GCP were influenced both by spontaneous changes and microbial activity. In naturally treated GCP, we revealed a decrease in volatile components like terpenoids, alongside variations in flavonoid content. After 36 months of storage, there was a significant increase in hesperitin content (0.084-0.103 mg/g), while nobiletin content exhibited a marked decrease (7.294-2.825 mg/g). Microbial community succession can be categorized into four distinct stages based on storage duration, with Rhodococcus and Apiotrichum emerging as the predominant microbial genera (>35 %) at the 36-month mark. These two taxon were thought to be potential microbial organisms contributing to the chemical transformations in GCP.

Pharmacological assessment of the extract and a novel compound of Bacillus velezensis DM derived from the rhizosphere of Datura metel L. with microbial molecular screening

BACKGROUND

Rhizosphere bacteria were considered a prospective reservoir of bioactive compounds with significant pharmacological efficacy.

METHODS

From the rhizosphere of Datura metel L., Bacillus velezensis DM was isolated and characterized using 16 S rRNA. PCR screening and sequencing were conducted to identify genes related to bioactive metabolite production. The extraction of secondary metabolites from the bacterial strain was performed via a fermentation process. The ethyl acetate extract of the propagated strain was subjected to fractionation and purification through various chromatographic techniques. The characterization of the isolated compounds was accomplished using different spectroscopic methods, such as 1D and 2D-NMR. An MTT test was conducted to assess the cytotoxic activity of bacterial extract on MCF-7, HepG-2, and HCT-116 cells. Furthermore, its pure compound (1) was tested for its cytotoxicity on HCT-116 and a normal cell (THLE2) to test its safety for normal cells. Apoptosis was identified through flow cytometry on HCT-116 cells after double-staining with PI and annexin V-FITC. The antioxidant action of bacterial extract was assessed through DPPH and ABTS assays. Furthermore, anti-inflammatory evaluations were carried out employing lipoxygenase (5-LOX) and cyclooxygenase (COX-2) inhibition.

RESULTS

The NCBI GenBank database has effectively incorporated the 16 S rRNA gene sequence of Bacillus velezensis DM under the accession number OR364492. Polyketide synthase and two lipopeptide genes for surfactin and iturin A were effectively detected by PCR, and their sequences were included in the Genbank database. A novel compound, 5,6-di(methylamino)hex-5-ene-1,2,3-triol (1), was successfully separated from the strain. Bacterial extract demonstrated significant cytotoxic activity against the evaluated cancer cells, exhibiting the most pronounced effect on HCT-116 cells. Compound (1) showed promising cytotoxic potential against HCT-116 cells with a higher selectivity index (2.5) towards cancer cells in comparison to Doxorubicin (1.49). Apoptosis assay showed that bacterial extract caused apoptosis about 14 folds compared to the control HCT-116 cells. Furthermore, it showed a potent anti-inflammatory outcome (IC50 = 1.927 µg/mL) and antioxidant activity at IC50 of 76.8 µg/mL.

CONCLUSION

This study revealed the possible pharmacological effects of secondary metabolites generated by Bacillus velezensis DM, making it a valuable resource for isolating bioactive compounds with potential therapeutic and biomedical uses.

Decoding endosperm endophytes in Pinus armandi: a crucial indicator for host response to climate change

BACKGROUND

Plant-associated microorganisms significantly contribute to plant survival in diverse environments. However, limited information is available regarding the involvement of endophytes in responding to climate change and their potential to enhance host plants' adaptation to future environmental shifts. Pinus armandi, endemic to China and widely distributed in climate-sensitive regions, serves as an ideal subject for investigating microbiome interactions that assist host plants in climate change response. Despite this, a comprehensive understanding of the diversity, community composition, and factors influencing endosperm endophytes in P. armandi, as well as the response of these endophytes to climate change, remains elusive.

RESULTS

In this study, transcriptome data from 55 P. armandi samples from 13 populations were analyzed to evaluate the composition and diversity of active endosperm endophytes and predict their response to future climate change. The results revealed variations in community composition, phylogenetic diversity, and interaction network between the northern and southern groups. Temperature and precipitation correlated with endosperm endophytic species richness and diversity. Under projected future climate conditions, the northern group exhibits greater genomic vulnerability and anticipates increased threats, reflecting a corresponding trend in endosperm endophytes, particularly within the Ascomycota community.

CONCLUSION

The consistent threat trend from climate change impacting both hosts and endophytes emphasizes the potential importance of host-related fungi as crucial indicators for predicting future climate impacts. Meanwhile, this study establishes an initial framework for exploring host-microbial interactions within the context of climate warming and provides valuable insights for studies related to plant protection.

Rhizosphere microbes facilitate the break of chlamydospore dormancy and root colonization of rice false smut fungi

Dormant chlamydospore germination of fungal pathogens directly affects disease occurrence and severity. The rice false smut (RFS) fungus Ustilaginoidea virens produces abundant chlamydospores, but their germination process and roles in plant infection remain unclear. Here, we found that soil-borne chlamydospores are a major source of U. virens inoculum and impact RFS development. Rhizosphere microbiome analysis of high-susceptibility (HS) and low-susceptibility (LS) rice varieties revealed that HS varieties recruited bacteria from the Sphingomonadaceae family, thereby facilitating the breakdown of chlamydospore dormancy through secreted exopolysaccharides. Hyphae formed by germinating chlamydospores grew on the root surfaces, invaded the root cortex, and grew intercellularly, potentially spreading further to aboveground plant parts. Furthermore, field experiments confirmed that treating the root with 30% prothioconazole and 20% zinc thiazole effectively reduced RFS incidence. Overall, these findings enhance our understanding of chlamydospore germination in natural environments and inform strategies for disease control.

The Role of Phenylpropanoids and the Plant Microbiome in Defences of Ash Trees Against Invasive Emerald Ash Borer

Plants have coevolved with herbivorous insects for millions of years, resulting in variation in resistance both within and between species. Using a manipulative experiment combined with untargeted metabolomics, microbiome sequencing and transcriptomics approaches, we investigated the roles of plant metabolites and the microbiome in defence mechanisms in native resistant Manchurian ash (Fraxinus mandshurica) trees and non-native susceptible velvet ash (Fraxinus velutina) trees against the highly invasive emerald ash borer (EAB, Agrilus planipennis). Comparative transcriptomics and metabolomics analyses show that the phenylpropanoid pathway, which is enriched in differentially expressed genes and differentially abundant metabolites, may serve as a potential regulator of resistance. Additionally, the microbiome is distinctly shifted in two ash species. Indicator taxa analysis reveals that the distinct genera are dominant in the galleries of two ash species, for example, Pseudomonas in velvet, and Hafnia-Obesumbacterium in Manchurian. The strong correlation between indicator taxa and metabolites suggests that the chemical compounds might impact the microbial community in phloem directly or indirectly, or vice versa. This study significantly enhances our understanding of the variation in resistance between ash species and its contribution to the invasion success of EAB, providing valuable insights for the development of pest management strategies.

Impact of Ectropis grisescens Warren (Lepidoptera: Geometridae) Infestation on the Tea Plant Rhizosphere Microbiome and Its Potential for Enhanced Biocontrol and Plant Health Management

The root-associated microbiome significantly influences plant health and pest resistance, yet the temporal dynamics of its compositional and functional change in response to Ectropis grisescens Warren (Lepidoptera: Geometridae) infestation remain largely unexplored. The study took samples of leaves, roots, and rhizosphere soil at different times after the plants were attacked by E. grisescens. These samples were analyzed using transcriptomic and high-throughput sequencing of 16S rRNA techniques. The goal was to understand how the plant's defense mechanisms and the microbial community around the roots changed after the attack. Additionally, bacterial feedback assays were conducted to evaluate the effects of selected microbial strains on plant growth and pest defense responses. By conducting 16S rRNA sequencing on the collected soil samples, we found significant shifts in bacterial communities by the seventh day, suggesting a lag in community adaptation. Transcriptomic analysis revealed that E. grisescens attack induced reprogramming of the tea root transcriptome, upregulating genes related to defensive pathways such as phenylpropanoid and flavonoid biosynthesis. Metagenomic data indicated functional changes in the rhizosphere microbiome, with enrichment in genes linked to metabolic pathways and nitrogen cycling. Network analysis showed a reorganization of core microbial members, favoring nitrogen-fixing bacteria like Burkholderia species. Bacterial feedback assays confirmed that selected strains, notably Burkholderia cepacia strain ABC4 (T1) and a nine-strain consortium (T5), enhanced plant growth and defense responses, including elevated levels of flavonoids, polyphenols, caffeine, jasmonic acid, and increased peroxidase (POD) and superoxide dismutase (SOD) activities. This study emphasizes the potential of utilizing root-associated microbial communities for sustainable pest management in tea cultivation, thereby enhancing resilience in tea crops while maintaining ecosystem balance.

Diversified Soil Types Differentially Regulated the Peanut (Arachis hydropoaea L.) Growth and Rhizosphere Bacterial Community Structure

Peanut (Arachis hydropoaea L.) demonstrates a prominent adaptability to diverse soil types. However, the specific effects of soil types on peanut growth and bacterial communities remain elusive. This study conducted a thorough examination of the agronomic traits, the corresponding physicochemical properties, and bacterial structure of rhizosphere soil in acidic (AT), neutral (NT), and saline-alkali (ST) soils, elucidating the internal relationship between soil type and peanut yield. Our results showed that different soil types exhibited significant differences in peanut yield, with ST demonstrating the lowest yield per plant, showing an 85.05% reduction compared to NT. Furthermore, available phosphorus content, urease, and invertase activities were substantially reduced in both ST and AT, particularly in ST by 95.35%, 38.57%, and 62.54%, respectively. Meanwhile, metagenomic sequencing unveiled a notable decline in Bradyrhizobium and Streptomyces in these soils, which is crucial for soil improvement. Further metabolic pathway analysis revealed that the reduction in pathways related to soil remediation, fertility improvement, and stress response in AT and ST may lead to slower peanut growth. In conclusion, peanuts cultivated in acidic and saline-alkali soils can increase yield via implementing soil management practices such as improving soil quality and refining micro-environments. Our study provides practical applications for enhancing peanut yield in low- to medium-yield fields.

Drivers of fungal and bacterial communities in ectomycorrhizospheres of birch, oak, and pine in a former uranium mining site, Ronneburg, Germany

The impact of soil and tree species on fungal and bacterial communities was investigated in a former uranium mining area with field and pot studies of the mycorrhizospheres of birch (Betula pendula), oak (Quercus robur), and pine (Pinus sylvestris). At the initial stages of succession re-created in the pot experiment, tree-species-specific microbial communities were detected. The pot microbiomes showed lower diversity and evenness of fungi and bacteria as compared to field-grown trees. In the natural field setting, the fungal community both in bulk and rhizosphere soil consisted of mainly Thelephoraceae, Inocybaceae and Russulaceae. They contributed with Leotiaceae and Herpotrichiellaceae to 52-85% of overall abundances, showing the soil hyphae impact of ectomycorrhiza in the tree stand. The fungal communities and their distribution patterns reflected host tree specificity and successional stage of the ectomycorrhizosphere. In the bacterial community, the most abundant bacterial classes were Alphaproteobacteria, Acidobacteria, Ktedonobacteria, Bacteroidia, Gammaproteobacteria, and Phycisphaerae representing about 59-80% of all bacterial sequences. The bacterial communities correlated with soil chemical parameters, particularly the content of toxic metals, total nitrogen and C/N ratio. This study allowed to identify drivers for microbial community composition, which might be helpful to develop afforestation strategies in post-mining landscapes.

Bacterial dynamics and exchange in plant-insect interactions

In nature, plants and insects engage in intricate interactions. Despite the increasing knowledge of the microbiomes of plants and insects, the extent to which they exchange and alter each other's microbiomes remains unclear. In this work, the bacterial community associated with nymphs of Philaenus spumarius (Hemiptera: Aphrophoridae), the stems of Coleostephus myconis where the nymphs were feeding, and the foam produced by the nymphs, were studied by culture-dependent and -independent approaches, with an attempt to elucidate the exchange of bacteria between plants and insects. The results suggest that both approaches complement each other, as many bacterial genera identified by metabarcoding were not detected by culturing, and vice versa. Overall, stems and foam exhibited higher bacterial diversity than nymphs, with all the samples showing enrichment in bacteria known to provide diverse benefits to their host. Stems and foam were the most similar in bacterial composition, but Burkholderiaceae and Moraxellaceae dominated the stems, whereas Rhizobiaceae and Sphingobacteriaceae dominated the foam. Nymphs exhibit the most distinct bacterial composition, yet more similar to that found in the stem compared to the foam. Indeed, nymphs were enriched on endosymbiotic bacteria, mostly Candidatus Sulcia and Sodalis, not found in the stem and foam. Nevertheless, during feeding, nymphs appeared to exchange several bacteria genera with C. myconis, with a significant number being incorporated into the bacteriome of the nymph. The genera Curvibacter, Cutibacterium, Methylobacterium, Pseudomonas and Rhizobium are likely the most exchanged. Nymphs also appear to exchange bacteria to the foam, notably species from the Enhydrobacter, Pseudomonas, Rhizobium and Roseomonas genera. More studies to infer the functions of the shared bacteria between P. spumarius-C. myconis are needed.

Serendipita indica-dominated synthetic microbial consortia enhanced tartary buckwheat growth and improved its tolerance to drought stress

The cultivation of tartary buckwheat serves dual roles, offering health benefits and nutritional advantages. Nonetheless, its cultivation is challenged by issues such as soil degradation and climatic drought. Plant growth-promoting (PGP) microorganisms hold promise for addressing these challenges. In this study, we investigated the effects of Serendipita indica inoculation on the root-associated microbial communities of tartary buckwheat. Additionally, we used S. indica to construct synthetic microbial consortia, and their role in promoting the growth and enhancing the drought resistance of tartary buckwheat was evaluated. This study found that the colonization of S. indica in tartary buckwheat promoted the enrichment of beneficial microorganisms such as Actinobacteriota, Sphingomonas, and Mortierella, while reducing the relative abundance of pathogenic genera including Cladosporium, Alternaria, and Acremonium. In addition, the inoculation of the microbial consortia significantly promoted the photosynthesis and biomass accumulation of tartary buckwheat, while also improving soil structure and fertility. Under drought conditions, introducing microbial groups markedly boosted root development, lowered the density of stomata and rate of transpiration in tartary buckwheat leaves, and decreased H2O2 and Malondialdehyde (MDA) levels, thus greatly enhancing tartary buckwheat's resistance to drought. In conclusion, our findings demonstrated that the microbial consortia constructed with S. indica can significantly promote the growth of tartary buckwheat and enhance its drought resistance. However, the specific molecular mechanisms underlying these effects require further investigation in future studies. These findings will provide important theoretical support for the development of novel microbial fertilizers.

The role of urinary microbiota in primary and recurrent bladder cancer: insights from a propensity score matching study

BACKGROUND

Bladder cancer (BCa) is a common urinary malignancy with high recurrence rates in non-muscle invasive bladder cancer (NMIBC), posing significant clinical challenges. Emerging evidence links urinary microbiota to cancer progression; however, their role in BCa recurrence remains unclear. This study aimed to explore urinary microbiota differences between primary and recurrent BCa to identify potential microbiological markers and mechanisms associated with recurrence.

METHODS

Urine samples were collected from 170 BCa patients, including 125 with primary Bca(BCa_P) and 45 with recurrent BCa (BCa_R). All samples underwent 16 S rRNA gene sequencing, and clinical data were collected, including age, sex, body mass index (BMI), smoking history, pathological grade, and other biological characteristics. Propensity score matching (1:1 ratio, caliper = 0.02) minimized baseline differences, resulting in 39 matched pairs. Microbial diversity was analyzed using α and β diversity indices. Differential taxa were identified with Linear Discriminant Analysis Effect Size (LEfSe), and functional pathways were predicted using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt).

RESULTS

Alpha diversity was significantly higher in BCa_P than BCa_R, particularly in Chao1 indices. β diversity revealed distinct microbial structures (ADONIS, P = 0.004, R² = 0.025). At the phylum level, both BCa_P and BCa_R were dominated by Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria, with Firmicutes significantly higher and Bacteroidetes lower in BCa_R. At the genus level, BCa_P was enriched in Sphingomonas, Corynebacterium, Capnocytophaga, Massilia, and Aquabacterium, while BCa_R showed higher levels of Aeromonas, Cupriavidus, and Bradyrhizobium. Functional predictions revealed glucose metabolism and oxidative stress pathways enriched in BCa_R, while pollutant degradation and TCA cycle pathways were prominent in BCa_P.

CONCLUSION

These findings reveal significant differences in urinary microbiota compositions and functional profiles between primary and recurrent BCa patients, with recurrent cases exhibiting reduced microbial diversity and enrichment of potentially pathogenic communities, highlighting their potential roles in tumor progression and recurrence.

TRIAL REGISTRATION

Registered with the Chinese Clinical Trial Registry (ChiCTR2300070969) on April 27, 2023.

Ironing out the conflicts: iron supplementation reduces negatives bacterial interactions in the rhizosphere of an Atacama-endemic perennial grass

BACKGROUND

In plants, root exudates selectively influence the growth of bacteria that colonize the rhizosphere. Bacterial communities associated with root systems are involved in macro and micronutrients cycling and organic matter transformation. In particular, iron is an essential micronutrient required for the proper functioning of iron-containing enzymes in processes such as photosynthesis, respiration, biomolecule synthesis, redox homeostasis, and cell growth in plants. However, the impact of changes of iron availability on the structure and set of ecological interactions taking place in the rhizosphere remains poorly understood. In this study, field experiments were conducted to compare the effects of iron supplementation (0.1 and 0.5 mM of FeSO4) on the assembly of the bacterial community of rhizosphere soil and bulk soil in a perennial grass present in the Andes steppe of Atacama Desert.

RESULTS

The results indicated that the difference in beta diversity between bulk soil and rhizosphere soil detected before supplementation did not persist after iron supplementation, in addition, co-occurrence networks showed a significant reduction in negative interactions among soil bacteria, mainly in rare taxa (< 0.1% relative abundance).

CONCLUSIONS

These observations suggest that iron availability contributes to the differentiation between bulk soil and rhizosphere bacterial communities, a process that is linked to significant changes in the relative abundance of more abundant species (> 0.1% relative abundance) and with a decrease in the negative interactions in both compartments after metal exposure. The differential effect of iron on the competition/cooperation ratio between bulk soils and the rhizosphere microbiome supports the hypothesis that the host limits the degree of cooperation that can be achieved by the bacterial community associated with an organ dedicated to nutrient absorption.

Leaf metabolomic traits decipher the invasiveness of Alternanthera philoxeroides in urban wetlands

Urbanisation has been considered to promote exotic plant invasion. Ecophysiology predicts phenotypic variation and potential evolution following urbanisation and can be used to evaluate plant invasiveness. However, few studies have included the role of ecophysiological traits for such invasiveness in urban ecosystems. Traditional plant functional traits have been used but have their limitations. Novel approaches such as metabolomics may potentially be useful. The present study explored the invasiveness of the cosmopolitan noxious invasive plant Alternanthera philoxeroides in urban and periurban areas of a megacity city in China using both traditional leaf functional traits and novel leaf metabolome as indicators. We found that traditional leaf functional traits, including specific leaf area, nitrogen concentration, carbon:nitrogen ratio and construction costs, did not differ between urban and periurban A. philoxeroides populations. However, metabolomic profiling showed that the urban populations had an up-regulated expression of zeatin and purine, two cytokinins correlated with plant growth and a down-regulated expression of isoflavonoids, a defensive metabolite for herbivory. Leaf metabolome may, therefore, be sensitive in deciphering the facilitative effects of urbanisation on plant invasion. We also found that the urban populations of A. philoxeroides accumulated more beneficial microbes, which might enhance their invasiveness. Urbanisation likely promotes exotic plants invasion through generation of metabolites, which stimulates growth via modification of the soil microbiome. Our results indicate that leaf metabolome may be used for interpreting plant invasiveness and predicting plant invasion.

Reshaped local microbiology metabolism by raw tea according to pile fermentation in the dark tea

INTRODUCTION

Traditionally, the mechanism of dark tea quality formation has centered on microorganisms, with quality regulated by manipulating microorganisms and their fermentation environment. Nevertheless, raw teas, the natural selective medium of microbial community, was completely ignored in the formation of dark tea unique flavors.

OBJECTIVES

This study aims to uncover the previously unappreciated interactions between raw tea and microorganisms, demonstrating the significant role of raw tea in the formation of dark tea quality.

METHODS

Sun-dried raw tea (SDT), baked raw tea (BT), and pan-fried raw tea (PFT) were pile fermented. Chemical profiles, microbial communities, and sensory qualities were assessed by metabolomics, high-throughput sequencing, and sensory evaluation, with correlation and multiple factor analyses used to explore their relationships.

RESULTS

Compared to PFT and BT, SDT had 18 % lower flavonoid content and 26 % lower catechin content, which favored dominant Agathobacter and Wickerhamomyces. Wickerhamomyces contributed to flower aroma by producing alcohols, esters and terpenes, while Agathobacter amplified acid production. The distinctive dominant bacterium Acidovorax in BT was positively correlated with alcohols and hydrocarbons, with Pearson's r > 0.6, resulting in a 47 % increase in volatile alcohol level, enhancing the fresh and refreshing attributes. A 70-80 % increase in iron concentration in PFT compared to SDT and BT resulted in the predominance of Geobacter, which exhibited a negative correlation with aldehydes. The presence of distinctive bacteria, Streptococcus and Ligilactobacillus, in PFT led to a significant rise in volatile acid content, increasing from 5 % to 25 %.

CONCLUSION

The chemical profiles of raw tea could reshape local microbiota, which then drives unique qualities of dark tea. This indicates dark tea quality is not passively shaped by the environmental microorganisms, but actively screened by raw tea chemistry. This study paves the way for targeted manipulation of raw tea chemical profiles to achieve desired dark tea flavor characteristics.

Analysis of the subtype I amidohydrolase responsible for Ochratoxin A degradation in the Sphingomonas genus

Ochratoxin A (OTA) is a mycotoxin that contaminates the agricultural environment, food and feed, leading to substantial economic losses. Among the alpha-proteobacteria, certain strains from the Sphingomonas genus are known to degrade a wide range of naturally occurring and synthetic compounds, including OTA. In this work, type strains for 17 Sphingomonas species were tested for their ability to detoxify OTA in culture. Most of them demonstrated OTA-detoxification capabilities. We observed that all OTA-degrading strains possessed an amidohydrolase homologous to others identified in gamma-proteobacteria. Conversely, strains that did not degrade OTA lacked this enzyme. This strong correlation suggests that the OTA-degrading phenotype exhibited by Sphingomonas cultures is directly linked to the presence of this enzyme. A PCR-based detection method was designed to identify strains possessing the amidohydrolase-encoding gene, marking them as potential OTA-degrading strains. Additionally, the OTA-transforming amidohydrolase from S. dokdonensis DSM 21029T (SdOTA) was identified and biochemically characterized. In silico prediction of the SdOTA structure with AlphaFold, combined with molecular docking simulations, revealed the structural basis of the substrate specificity and insights into the mycotoxin-binding mechanism. The ability Sphingomonas strains to detoxify OTA, coupled with the collection of genes enabling bioremediation, positions them as highly versatile bacteria for pollutant detoxification.

Preparation and characterization of the octenyl succinic anhydride (OSA) modified sphingan WL gum as novel biopolymeric surfactants

Combining polymer and surfactant in one agent namely polymeric surfactants with both high viscosity and surface activity has become a viable alternative for the traditional enhanced oil recovery (EOR) processes. With the purpose of developing new polymeric surfactants, the biopolymer flooding agent sphingan WL gum was modified by octenyl succinic anhydride (OSA) through the esterification reaction. The effects of molecular weight (MW) of WL and the OSA: WL ratio on the properties of the products were investigated. As the OSA concentration increased, the degree of substitution was increased. WL2 with the medium MW was the best substrate and the optimal OSA:WL was 1:1; the obtained sample OSA-WL2-2 exhibited good viscosity and surface activity. Compared with WL2, its viscosity (23 mPa·s) was increased by 75.98 %; the surface tension decreased from 59.30 mN/m to 48.13 mN/m, and the critical micelle concentration was 2.29 mg/mL; the emulsifying activity index was increased by 57.18 %. OSA-WL2-2 also had higher elastic modulus G' and salt tolerance due to its increased MW and intermolecular association among the hydrophilic and hydrophobic groups. OSA-WL2-2 showed higher oil washing efficiency (78.6 %) than the commonly-used polyacrylamide, SDS and modified cellulose samples and made it a potential flooding agent in EOR.

Unveiling Microbial Dynamics: How Forest Aging Shapes the Microbial Communities of Pinus massoniana

Plants host diverse microbial communities essential for nutrient acquisition, growth, and responses to biotic and abiotic stresses. Despite their importance, the variation and stability of these communities during forest succession remain poorly understood. This study investigated the microbial communities in Pinus massoniana forests at different stand ages (12, 22, 30, and 40 years). Results showed that the phyllosphere and roots of P. massoniana harbor diverse microbial communities, which shift dynamically with forest aging. Bacterial species diversity consistently surpassed fungal diversity across all habitats. Forest aging significantly influenced the alpha diversity of phyllosphere and soil microbes, whereas root-associated microbial diversity remained stable. Co-occurrence network analysis revealed that bacterial communities formed more complex networks than fungal communities and exhibited greater stability. Functional annotation confirmed that bacterial communities were functionally more stable, predominantly involving metabolic processes. In contrast, endophytes dominated the phyllosphere fungi, while ectomycorrhizal fungi were prevalent in root and soil fungal communities. Environmental factors, including total nitrogen, total phosphorus, available potassium, and pH, emerged as key drivers of microbial dynamics. These findings provide novel insights into the differing responses of bacterial and fungal communities to forest aging, highlighting the critical role of ecological niches in shaping microbial dynamics.

Metagenomic Characterization of the Maerua crassifolia Soil Rhizosphere: Uncovering Microbial Networks for Nutrient Acquisition and Plant Resilience in Arid Ecosystems

Background/Objectives:Maerua crassifolia, a threatened medicinal species endemic to drylands, exhibits a pronounced drought sensitivity. Despite the critical role of microorganisms, particularly bacteria and fungi, the microbial consortia in M. crassifolia's rhizosphere remain underexplored. Methods: Metagenomic whole genome shotgun sequencing (WGS) was employed to elucidate the taxonomic composition of bacterial and fungal communities inhabiting the soil rhizosphere of M. crassifolia. Results: The data revealed a marked predominance of bacterial genomes relative to fungal communities, as evidenced by non-redundant gene analysis. Notably, arbuscular mycorrhizal fungi (AMF), specifically Rhizophagus clarus, Rhizophagus irregularis and Funneliformis geosporum, are key rhizosphere colonizers. This study confirmed the presence of phosphate-solubilizing bacteria (PSB), such as Sphingomonas spp., Cyanobacteria and Pseudomonadota, underscoring the critical role of these microorganisms in the phosphorus cycle. Additionally, the study uncovered the presence of previously uncharacterized species within the phylum Actinobacteria, as well as unidentified taxa from the Betaproteobacteria, Gemmatimonadota and Chloroflexota phyla, which may represent novel microbial taxa with potential plant growth-promoting properties. Conclusions: Findings suggest a complex, symbiotic network where AMF facilitate phosphorus uptake through plant-root interactions. In a tripartite symbiosis, PSB enhance inorganic phosphorus solubilization, increasing bioavailability, which AMF assimilate and deliver to plant roots, optimizing nutrition. This bacterial-fungal interplay is essential for plant resilience in arid environments. Future investigations should prioritize the isolation and characterization of underexplored microbial taxa residing in the rhizosphere of M. crassifolia, with particular emphasis on members of the Actinobacteria, Betaproteobacteria, Gemmatimonadota and Chloroflexota phyla to uncover their roles in nutrient acquisition and sustainability.

Microbial Community Structure and Diversity of Endophytic Bacteria and Fungi in the Healthy and Diseased Roots of Angelica sinensis, and Identification of Pathogens Causing Root Rot

Angelica sinensis (Oliv.) Diels is an important traditional Chinese herbal medicine, and its main medicinal part is the root. In recent years, root rot has become one of the bottlenecks hindering the healthy and green development of Angelica cultivation due to the inappropriate application of chemical fertilizers, pesticides, plant growth regulators, and continuous cropping. In this study, high-throughput sequencing technology was adopted to reveal the differences in the community structure and diversity of endophytic bacteria and fungi in the roots of healthy and diseased A. sinensis. The results showed that the diversity index of endophytic bacterial communities was significantly higher in healthy root than in diseased Angelica root systems. There was a significant difference in endophytic fungal community diversity only at the m1 sampling site. There was a significant difference in the β-diversity of bacterial communities, but not of fungi. In terms of community composition, Proteobacteria was the dominant phylum of bacteria, and Sphingobium and Pseudomonas were the dominant genera; Ascomycota and Basidiomycota were the dominant phyla of fungi, and Plectosphaerella, Paraphoma, and Fusarium were the dominant genera. In addition, the relative abundance of the genera Sphingobium and Pseudomonas was higher in healthy roots, while Fusarium was higher in diseased samples. Among the five pathogens isolated from diseased root, four strains were Fusarium sp., and one was Paraphoma chrysanthemicola, which is reported for the first time. Our findings indicate that the endophyte community structure of A. sinensis infected with root rot changed significantly compared with healthy plants, and Fusarium is an important pathogenic factor, which provides a valuable microbiological basis for the targeted biocontrol of Angelica root rot.

Three local plants adapt to ecological restoration of abandoned lead-zinc mines through assembly of rhizosphere bacterial communities

Introduction

The plant restoration and ecological restoration of lead-zinc mines are very important.

Methods

In this study, we used three local plants to carry out ecological restoration of abandoned lead-zinc mining areas and detected the adaptive mechanisms of soil bacterial diversity and function during the ecological restoration of lead-zinc mines through 16S rRNA sequencing.

Results

The results revealed that lead-zinc mining significantly reduced the soil bacterial diversity, including the Shannon, Simpson, and observed species indices, whereas the planting of the three ecological restoration plants restored the soil microbial diversity to a certain extent, leading to increases in the Shannon index and Observed species indices. Mining activities significantly reduced the abundances of RB41 and Bryobacter in the bulk soil compared with those in the nonmining areas, whereas the three ecological restoration plants increased the abundances of RB41 and Bryobacter in the rhizosphere soil compared with those in the bulk soil in the mining areas. Following the planting of the three types of ecologically restored plants, the soil bacterial community structure partially recovered. In addition, different plants have been found to have different functions in the lead-zinc ecological restoration process, including iron complex transport system-permitting proteins and ATP binding cassettes.

Discussion

This study confirms for the first time that plants adapt to the remediation process of abandoned lead-zinc mines by non-randomly assembling rhizosphere bacterial communities and functions, providing a reference for screening microbial remediation bacterial resources and plant microbe joint bioremediation strategies for lead-zinc mines.

Transgenic Maize of ZmMYB3R Shapes Microbiome on Adaxial and Abaxial Surface of Leaves to Promote Disease Resistance

The phyllosphere is one of the largest habitats for microorganisms, and host genetic factors play an important role during the interaction between microorganisms and the phyllosphere. Therefore, the transgene may also lead to changes in the maize phyllosphere. ZmMYB3R was identified as a drought-tolerant gene in Arabisopsis. Here, we employed metagenomic sequencing to analyze the microbiome of the adaxial and abaxial leaf surfaces on ZmMYB3R-overexpressing (OE) and wild-type (WT)·maize, aiming to dissect the possible associations between ZmMYB3R and changes in phyllosphere microbiome functioning. Our results revealed that overexpressing ZmMYB3R altered the alpha and beta diversity of the phyllosphere microbiome. In OE plants, more beneficial microbes accumulated on the phyllosphere, while pathogenic ones diminished, especially on the abaxial surface of ZmMYB3R leaves. Further analysis of disease resistance-related metabolic pathways and abundances of disease resistance genes revealed significant differences between OE and WT. The inoculation experiment between OE and WT proved that ZmMYB3R increased the disease resistance of maize. In conclusion, the results reveal that transgenes affect the phyllosphere microbiome, and ZmMYB3R might alter leaf disease resistance by reshaping the phyllosphere microbiome structure. These findings help us understand how ZmMYB3R regulates leaf disease resistance and may facilitate the development of disease control by harnessing beneficial microbial communities.

Modulation of Terpenoid Indole Alkaloid Biosynthesis in Catharanthus roseus by Sphingomonas Sp Y503 via the CrMAPKKK1-CrMAPKK1/CrMAPKK2-CrMPK3 Signaling Cascade

Catharanthus roseus is a highly relevant model for investigating plant defense mechanisms and the biosynthesis of therapeutically valuable compounds, including terpenoid indole alkaloids (TIAs). It has been demonstrated that beneficial microbial interactions can regulate TIA biosynthesis in C. roseus, highlighting the need to fully comprehend the molecular mechanisms involved to efficiently implement eco-friendly strategies. This study explores the effects of a novel microbial strain, Y503, identified as Sphingomonas sp., on TIA production and the underlying mechanisms in C. roseus. Through bioinformatics analysis, we have identified 17 MAPKKKs, 7 MAPKKs, and 13 MAPKs within the C. roseus genome. Further investigation has verified the presence of the MAPK module (CrMAPKKK1-CrMAPKK1/CrMAPKK2-CrMPK3) mediating Y503 in regulating TIA biosynthesis in C. roseus. This study provides foundational information for strengthening the plant defense system in C. roseus through advantageous microbial interactions, which could contribute to the sustainable cultivation of medicinal plants such as C. roseus.

Trees shape the soil microbiome of a temperate agrosilvopastoral and syntropic agroforestry system

Agroforestry systems are multifunctional land-use systems that promote soil life. Despite their large potential spatio-temporal complexity, the majority of studies that investigated soil organisms in temperate cropland agroforestry systems focused on rather non-complex systems. Here, we investigated the topsoil and subsoil microbiome of two complex and innovative alley cropping systems: an agrosilvopastoral system combining poplar trees, crops, and livestock and a syntropic agroforestry system combining 35 tree and shrub species with forage crops. Increasing soil depth resulted in a decline of bacterial and fungal richness and a community shift towards oligotrophic taxa in both agroforestry systems, which we attribute to resource-deprived conditions in subsoil. At each soil depth, the microbiome of the tree rows was compositionally distinct from the crop rows. We detected a shift towards beneficial microorganisms as well as a decline in putative phytopathogens under the trees as compared to the crop rows. Finally, based on our results on community dissimilarity, we found that compared to an open cropland without trees, spatial heterogeneity introduced by the tree rows in the agrosilvopastoral system translated into a compositionally less homogeneous soil microbiome, highlighting the potential of agroforestry to counteract the homogenization of the soil microbiome through agriculture.

Phage Cocktail Alleviates Bacterial Canker of Kiwifruit by Modulating Bacterial Community Structure in Field Trial

Bacterial canker of kiwifruit is the most destructive bacterial disease caused by Pseudomonas syringae pv. actinidiae. Bacteriophages are regarded as promising biocontrol agents against kiwifruit bacterial pathogens due to their exceptional host specificity and environmentally friendly nature. However, the underlying mechanism of phages in the control of kiwifruit bacterial canker disease remains elusive. In this study, the field trial results showed that phage cocktail could significantly reduce the incidence of bacterial canker in kiwifruit. The high throughput sequencing results showed that the phage cocktail regulated the impact of pathogen invasion on branch endophytic communities, adjusted the diversity of the bacterial community structure, regulated the composition of rare taxa and abundant taxa, and increased the proportion of deterministic processes in community assembly processes. The phage cocktail significantly reduced the relative abundance of Pseudomonadaceae, Pectobacteriaceae, and Yersiniacea. Furthermore, the application of the phage cocktail resulted in an increase in the relative abundance of Beijerinckiaceae, Sphingomonadaceae, and Xanthomonadaceae, most of which are abundant taxa of the corresponding microbial communities. Additionally, the composition of rare taxa was also altered under the influence of phages. These findings offer perspectives on the phage-mediated biocontrol of kiwifruit bacterial canker and provide practical backing for the implementation of phage cocktails in sustainable agriculture.

Melatonin reprograms soil microbial community, creates friendly soil environments, and promotes peanut growth

Melatonin helps to regulate various physiological processes in plants, including growth, seed germination, and stress responses. However, the mechanism of how melatonin treatments affect soil microbe diversity and ecology, and plant growth needs to be better understood. Here, we report that melatonin coordinates interactions between soil microorganisms and root exudates to create a friendly soil environment for peanut growth under a controlled environment. Interestingly, the results showed that melatonin was capable of regulating the structure of the soil microbial community, improving its relative abundance of beneficial microorganisms (such as Sphingomonas, Trichoderma, and Penicillium) in the soil. Furthermore, melatonin could also change the composition of soil metabolites and nutrients. These altered soil profiles reflected a healthy environment for peanuts created by melatonin. Furthermore, the favorable growing environment increased photosynthetic performance, biomass, and peanut yield. Collectively, our findings will help us better understand the role of melatonin as a bioregulator in maintaining a healthy plant growth environment. SYNOPSIS: Melatonin treatments improved soil microbe biodiversity and enhanced plant growth and development and sustainable agricultural development.

The influence of rhizosphere microbial diversity on the accumulation of active compounds in farmed Scutellaria baicalensis

Rhizosphere microorganisms are important factors affecting herb quality and secondary metabolite accumulation. In this study, we investigated the diversity of rhizosphere microbial communities (bacteria and fungi) and their correlations with soil physicochemical properties and active compounds of Scutellaria baicalensis (baicalin, oroxindin, baicalein, wogonin, and oroxylin A) from cultivated Scutellaria baicalensis with three different origins via high-throughput sequencing and correlation analysis to further clarify the role of soil factors in the accumulation of the active compounds of Scutellaria baicalensis. The results are summarized as follows. A total of 28 dominant bacterial genera, such as Arthrobacter, Rubrobacter, Microvirga, and Sphingomonas, and 42 dominant fungal genera, such as Alternaria, Spegazzinia, and Minimedusa, were detected. The soil microbial communities associated with cultivated Scutellaria baicalensis were very diverse, but there were some differences in the relative abundances of microbial taxa. Correlation analysis revealed that the bacterial genera Rubrobacter, Ellin6055, Gaiella, norank__f__norank__o___norank__c__bacteriap25, unclassified__f__Micromonosporaceae, norank__f__ Gemmatimonadaceae, Arthrobacter, and Sphingomonas and the fungal genera Tausonia, Minimedusa, Cercospora, Botrytis, Alternaria, Boeremia, Titaea, Solicoccozyma, and Mortierella were positively or negatively correlated with each active component of Scutellaria baicalensis and were important genera affecting the accumulation of the active compounds of Scutellaria baicalensis and correlated with soil physiochemistry to different degrees. These results suggest that rhizosphere microorganisms may play a role in the accumulation of active compounds in medicinal plants and provide a scientific basis for guiding the cultivation of Scutellaria baicalensis, developing biofertilizers, and improving the quality of Scutellaria baicalensis medicinal materials.

UV-C Exposure Enhanced the Cd2+ Adsorption Capability of the Radiation-Resistant Strain Sphingomonas sp. M1-B02

Microbial adsorption is a cost-effective and environmentally friendly remediation method for heavy metal pollution. The adsorption mechanism of cadmium (Cd) by bacteria inhabiting extreme environments is largely unexplored. This study describes the biosorption of Cd2+ by Sphingomonas sp. M1-B02, which was isolated from the moraine on the north slope of Mount Everest and has a good potential for biosorption. The difference in Cd2+ adsorption of the strain after UV irradiation stimulation indicated that the adsorption reached 68.90% in 24 h, but the adsorption after UV irradiation increased to 80.56%. The genome of strain M1-B02 contained antioxidant genes such as mutL, recA, recO, and heavy metal repair genes such as RS14805, apaG, chrA. Hydroxyl, nitro, and etceteras bonds on the bacterial surface were involved in Cd2+ adsorption through complexation reactions. The metabolites of the strains were significantly different after 24 h of Cd2+ stress, with pyocyanin, L-proline, hypoxanthine, etc., being downregulated and presumably involved in Cd2+ biosorption and upregulated after UV-C irradiation, which may explain the increase in Cd2+ adsorption capacity of the strain after UV-C irradiation, while the strain improved the metabolism of the antioxidant metabolite carnosine, indirectly increasing the adsorption capacity of the strains for Cd2+.

Baseline microbiota of blueberries, soil, and irrigation water from blueberry farms located in three geographical regions

Bacterial microbiota was determined in fruit, soil, and irrigation water from blueberry (Vaccinium spp.) farms located in Cundinamarca, Colombia; Mississippi, United States; and Jalisco, Mexico. Bacterial communities were studied using 16S ribosomal ribonucleic acid (rRNA) gene amplification by targeting the V3-V4 hypervariable region. The most abundant phylum in fruit was Proteobacteria in Colombia and the United States and Firmicutes in Mexico. The most abundant phylum in soil and water was Proteobacteria for all regions. The top three genera found in fruit were Heliorestis (9.2 %), Rhodanobacter (3.3 %), and Sphingomonas (2.8 %) for Colombia, Heliorestis (23.1 %), Thiomonas (8.5 %), and Methylobacterium (3.3 %) for the United States, and Heliorestis (47.4 %), Thiomonas (9.1 %), and Bacillus (4.6 %) for Mexico. Colombia reported the highest (Padj < 0.05) alpha diversity for blueberries, and United States and Mexico had similar (Padj > 0.05) results. Beta diversity revealed bacterial communities in fruit differed (P < 0.05) by region. Bacterial differences existed between Colombia, United States, and Mexico for soil and fruit (P = 0.021, 0.003, and 0.006, respectively) and water and fruit (P = 0.003, 0.003, and 0.033, respectively). Blueberries grown in the three different regions have unique microbiota. Fruit and fruit-environment microbial composition also differed by region. These results provide a more complete profile of the bacterial communities on blueberries and their agricultural environments and could contribute to better management and decision-making practices in terms of plant health, food quality, and food safety.

Mitigating the effects of polyethylene microplastics on Pisum sativum L. quality by applying microplastics-degrading bacteria: A field study

Polyethylene microplastics (PE-MPs) have been widely reported for their adverse effects on soil ecosystems. However, there are fewer field studies on addressing PE-MPs contamination in soil. This study investigated the effects of PE-MPs on soil properties, rhizosphere soil microorganisms, and pea (Pisum sativum L.) nutrient composition in a field experiment and mitigated the effects of PE-MPs by adding MPs-degrading bacteria. The results showed that the addition of MPs-degrading bacteria mitigated the effects of PE-MPs on the hydrolyzable nitrogen content in the soil. In addition, the introduction of MPs-degrading bacteria resulted in an increase in the Shannon indices of microorganisms in the soil. This also effectively regulates the structure of the soil microbial community to be closest to that of normal soil. Notably, the addition of MPs-degrading bacteria increased the protein, starch, cellulose, and chlorophyll contents of pea grains. This study demonstrated the ability to improve the nutrient content of peas affected by MPs by adding MPs-degrading bacteria. This study contributes to our understanding of the effects of PE-MPs on soil-microbe-plant systems and provides new insights into the bioremediation of PE-MPs in agricultural soils.

Exploring and exploiting the rice phytobiome to tackle climate change challenges

The future of agriculture is uncertain under the current climate change scenario. Climate change directly and indirectly affects the biotic and abiotic elements that control agroecosystems, jeopardizing the safety of the world's food supply. A new area that focuses on characterizing the phytobiome is emerging. The phytobiome comprises plants and their immediate surroundings, involving numerous interdependent microscopic and macroscopic organisms that affect the health and productivity of plants. Phytobiome studies primarily focus on the microbial communities associated with plants, which are referred to as the plant microbiome. The development of high-throughput sequencing technologies over the past 10 years has dramatically advanced our understanding of the structure, functionality, and dynamics of the phytobiome; however, comprehensive methods for using this knowledge are lacking, particularly for major crops such as rice. Considering the impact of rice production on world food security, gaining fresh perspectives on the interdependent and interrelated components of the rice phytobiome could enhance rice production and crop health, sustain rice ecosystem function, and combat the effects of climate change. Our review re-conceptualizes the complex dynamics of the microscopic and macroscopic components in the rice phytobiome as influenced by human interventions and changing environmental conditions driven by climate change. We also discuss interdisciplinary and systematic approaches to decipher and reprogram the sophisticated interactions in the rice phytobiome using novel strategies and cutting-edge technology. Merging the gigantic datasets and complex information on the rice phytobiome and their application in the context of regenerative agriculture could lead to sustainable rice farming practices that are resilient to the impacts of climate change.

Geographic Distribution Pattern Determines Soil Microbial Community Assembly Process in Acanthopanax senticosus Rhizosphere Soil

The geographic distribution patterns of soil microbial communities associated with cultivated Acanthopanax senticosus plants in Northeast China were investigated. High-throughput sequencing revealed that the diversity and community assembly of bacterial and fungal communities in the inter-root soil varied significantly with geographic location. The study found that bacterial communities were predominantly assembled through stochastic processes at most sites, while fungal communities showed greater variation, with both stochastic and deterministic processes involved. The complexity of bacterial-fungal co-occurrence networks also varied with longitude and latitude, demonstrating both positive and negative interactions. PICRUSt 2.0 and FUNGuild were used to predict the potential functions of soil bacterial and fungal microbiota, respectively, during different land use patterns. The average taxonomic distinctness (AVD) index indicated varying degrees of community stability across sites. Key microbial taxa contributing to community variability were identified through Random Forest modeling, with Bacteriap25 and Sutterellaceae standing out among bacteria, and Archaeorhizomyces and Clavaria among fungi. Soil chemical properties, including pH, TN, TP, EC, and SOC, significantly correlated with microbial diversity, composition, and co-occurrence networks. Structural equation modeling revealed that geographic distribution patterns directly and indirectly influenced soil chemical properties and microbial communities. Overall, the study provides insights into the geographic distribution patterns of soil microbial communities associated with A. senticosus and highlights the need for further research into the underlying mechanisms shaping these patterns.

Phosphate solubilization and plant growth properties are promoted by a lactic acid bacterium in calcareous soil

On the basis of good phosphate solubilization ability of a lactic acid bacteria (LAB) strain Limosilactobacillus sp. LF-17, bacterial agent was prepared and applied to calcareous soil to solubilize phosphate and promote the growth of maize seedlings in this study. A pot experiment showed that the plant growth indicators, phosphorus content, and related enzyme activity of the maize rhizospheric soils in the LF treatment (treated with LAB) were the highest compared with those of the JP treatment (treated with phosphate solubilizing bacteria, PSB) and the blank control (CK). The types of organic acids in maize rhizospheric soil were determined through LC-MS, and 12 acids were detected in all the treatments. The abundant microbes belonged to the genera of Lysobacter, Massilia, Methylbacillus, Brevundimonas, and Limosilactobacillus, and they were beneficial to dissolving phosphate or secreting growth-promoting phytohormones, which were obviously higher in the LF and JP treatments than in CK as analyzed by high-throughput metagenomic sequencing methods. In addition, the abundance values of several enzymes, Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology, and Carbohydrate-Active Enzymes (CAZys), which were related to substrate assimilation and metabolism, were the highest in the LF treatment. Therefore, aside from phosphate-solubilizing microorganisms, LAB can be used as environmentally friendly crop growth promoters in agriculture and provide another viable option for microbial fertilizers. KEY POINTS: • The inoculation of LAB strain effectively promoted the growth and chlorophyll synthesis of maize seedlings. • The inoculation of LAB strain significantly increased the TP content of maize seedlings and the AP concentration of the rhizosphere soil. • The inoculation of LAB strain increased the abundances of the dominant beneficial functional microbes in the rhizosphere soil.

Distinct microbial communities associated with health-relevant wild berries

Lingonberries (Vaccinium vitis-idaea L.), rowanberries (Sorbus aucuparia L.) and rosehips (Rosa canina L.) positively affect human health due to their healing properties, determined by a high content of bioactive compounds. The consumption of unprocessed wild berries is relevant and encouraged, making their in-depth microbiological characterization essential for food safety. This study presents the first high-throughput sequencing analysis of bacterial and fungal communities distributed on the surface of lingonberries, rowanberries and rosehips. Significant plant-defined differences in the taxonomic composition of prokaryotic and eukaryotic microbiota were observed. The bacterial community on rosehips was shown to be prevalent by Enterobacteriaceae, lingonberries by Methylobacteriaceae and rowanberries by Sphingomonadaceae representatives. Among the fungal microbiota, Dothioraceae dominated on rosehips and Exobasidiaceae on lingonberries; meanwhile, rowanberries were inhabited by a similar level of a broad spectrum of fungal families. Cultivable yeast profiling revealed that lingonberries were distinguished by the lowest amount and most distinct yeast populations. Potentially pathogenic to humans or plants, as well as beneficial and relevant biocontrol microorganisms, were identified on tested berries. The combination of metagenomics and a cultivation-based approach highlighted the wild berries-associated microbial communities and contributed to uncovering their potential in plant health, food and human safety.

The Phyllosphere Microbial Community Structure of Three Camellia Species upon Anthracnose

Anthracnose of Camellia plants is caused by the Colletotrichum species. The fungal pathogens mainly infect the leaves of plants and lead to serious economic losses. However, knowledge of Camellia phyllosphere microbial community after Colletotrichum infection has not been explored which limited our understanding of the relationship between the Camellia anthracnose outbreak and interacting microorganisms. In this study, three economically and ecologically important Camellia species with anthracnose symptoms were collected and subjected to bacterial and fungal composition analysis, diversity, co-occurrence characteristics, isolation of key strains, and tie-back pathogenicity test. The results indicated that Sphingomonas and Methylobacterium were the dominant bacterial genera over the three Camellia species and Pallidocercospora, Colletotrichum, and Pichia were the dominant fungal genera. The co-occurrence analysis showed that Methylobacterium, Sphingomonas, Massilia, and Allorhizobium were the key bacterial taxa and Colletotrichum, Pallidocercospora, Pichia, Septophoma, and Septoria were the key fungal taxa over the three infected plants. The hub taxa, including the species significantly associated with the Colletotrichum abundance, were mostly beneficial bacteria over the three Camellia species. Further co-culture and tie-back pathogenicity tests verified that the hub taxa associated with pathogenic Colletotrichum in the microbial networks may play promoting/inhibiting roles on Colletotrichum infection. The results highlight the importance of phytopathological conditions for the interactions between microbial members of foliar fungal and bacterial communities.

Effects of Coffea canephora genotypes on the microbial community of soil and fruit

In recent years, the role of microbial communities in agricultural systems has received increasing attention, particularly concerning their impact on plant health and productivity. However, the influence of host plant genetic factors on the microbial composition of coffee plants remains largely unexplored. This study provides the first comprehensive investigation into how genotype affects the microbial communities present in the rhizosphere and fruits of Coffea canephora. Conducted on a commercial coffee farm in Brazil, we analyzed six genotypes of C. canephora var. Conilon. Soil and fruit samples were collected from which microbial DNA was extracted and sequenced, targeting the V3-V4 region of the 16 S rDNA and the ITS1 region for fungi. A total of 12,239,769 reads were generated from the 16 S rDNA and ITS1 regions. The PCoA revealed distinct patterns of beta diversity, with genotype 153 exhibiting significant isolation in soil bacterial communities. The dominant bacterial orders included Rhizobiales and Rhodobacterales, while the fungal community comprised diverse taxa from Saccharomycetales and Hypocreales. LEfSe analysis identified key metagenomic biomarkers, highlighting genotype Baiano 4 for its richness in fruit-associated taxa, whereas genotype 153 exhibited lower diversity in both soil and fruit samples. This work enhances our understanding of the microbiomes associated with different coffee genotypes, providing evidence of how host genetic variation influences microbial community composition. Our findings indicate that specific microbial taxa are enriched in the fruits and soil of various genotypes. Future research should focus on identifying these microorganisms and elucidating their specific functions within the rhizosphere and coffee fruits.

The Bacteria of a Fig Microcommunity

Understanding the biotic drivers of diversity is a major goal of microbial ecology. One approach towards tackling this issue is to interrogate relatively simple communities that are easy to observe and perturb. Figs (syconia) of the genus Ficus represent such a system. Here, we describe the microbial communities of Ficus septica figs, which are associated with the nematode Caenorhabditis inopinata (the sister species of the C. elegans genetic model system). In 2019, 38 Ficus septica figs (across 12 plants in Taiwan) were dissected, and metadata such as foundress wasp number and nematode occupancy were collected for each fig. Suspensions derived from interior fig material and fig surface washes were prepared for 16S microbial metabarcoding. Over 3,000 OTUs were detected, and microbial communities were dominated by members of Proteobacteria , Bacteroidota , and Actinobacteriota . Although microbial communities of fig exteriors and interiors can be distinguished, levels of microbial alpha diversity were comparable across these areas of the fig. Nematodes likewise had no detectable impact on microbial alpha diversity, although nematodes were associated with a modest change in microbial community composition. A handful of OTUs (associated with the genera Kosokonia , Ochobactrum , and Stenotrophomonas ) revealed potential differential abundance among figs varying in nematode occupancy. Additionally, foundress wasp number was negatively correlated with microbial alpha diversity. These findings set the stage for future studies that directly test the role of nematode and wasp occupancy on microbial communities, as well as investigations that probe nematode-microbe interactions through laboratory experiments. Taken together, these results constitute a fundamental step in characterizing the natural microbial communities of figs and Caenorhabditis nematodes.

Importance

Unraveling why different species live in different places is a longstanding open question in ecology, and it is clear that interspecific interactions among species are a major contributor to species distributions. Ficus figs are a useful system for ecological studies because they are relatively simple microcosms where characterizing animal community composition of multiple samples is straightforward. Additionally, Caenorhabditis inopinata , a close relative of the C. elegans genetic model system, thrives in Ficus septica figs. Here, we tie 16S microbial metabarcoding to nematode and wasp occupancy data to understand the causes of bacterial community composition in F. septica figs. We found that microbial composition, but not total diversity, varies among fig surface and interiors. Likewise, we found that nematode occupancy impacts microbial composition but not alpha diversity. Moreover, we show that as the number of foundress wasps increases, the microbial alpha diversity decreases. Finally, we identified OTUs that are potentially associated with nematode occupancy. Taken together, these results represent a key step in describing a microcommunity wherein ecological genetic hypotheses can be tested, as well as one that can potentially reveal the roles of uncharacterized genes in established model systems.

Divergence and convergence in epiphytic and endophytic phyllosphere bacterial communities of rice landraces

Phyllosphere-associated microbes can significantly alter host plant fitness, with distinct functions provided by bacteria inhabiting the epiphytic (external surface) vs endophytic niches (internal leaf tissue). Hence, it is important to understand the assembly and stability of these phyllosphere communities, especially in field conditions. Broadly, epiphytic communities should encounter more environmental fluctuations and frequent immigration, whereas endophytic microbiota should face stronger host selection. As a result, we expect greater variability in epiphytic than endophytic communities. We analyzed the structure and stability of leaf phyllosphere microbiota of four traditionally cultivated rice landraces and one commercial variety from northeast India grown in the field for 3 consecutive years, supplemented with opportunistic sampling of eight other landraces. Epiphytic and endophytic bacterial communities shared dominant core genera such as Methylobacterium and Sphingomonas. Consistent with an overall strong environmental effect, both communities varied more across sampling years than across host landraces. Seeds sampled from a focal landrace did not support vertical transmission of phyllosphere bacteria, suggesting that both types of communities are assembled anew each generation. Despite these points of convergence, epiphytic communities had distinct composition and significantly higher microbial load and were more rich, diverse, modular, and unstable than endophytic communities. Finally, focused sampling of one landrace across developmental stages showed that the divergence between the two types of communities arose primarily at the flowering stage. Thus, our results show both convergent and divergent patterns of community assembly and composition in distinct phyllosphere niches in rice, identifying key bacterial genera and host developmental stages that may aid agricultural interventions to increase rice yield.IMPORTANCEPhyllosphere (leaf-associated) microbes significantly impact plant fitness, making it crucial to understand how these communities are assembled and maintained. While many studies have analyzed epiphytic (surface) phyllosphere communities, we have a relatively poor understanding of endophytic communities which colonize the very distinct niche formed inside leaf tissues. We found that across several rice landraces, both communities are largely colonized by the same core genera, indicating divergence at the species level across the two leaf niches and highlighting the need to understand the mechanisms underlying this divergence. Surprisingly, both epiphytic and endophytic communities were only weakly shaped by the host landrace, with a much greater role for environmental factors that likely vary over time. Thus, microbiome-based agricultural interventions for increasing productivity could perhaps be generalized across rice varieties but would need to account for the temporal instability of the microbiota. Our results thus highlight the importance of data sets such as ours-with extensive sampling across landraces and years-for understanding phyllosphere microbiota and their applications in the field.

Synthetic communities derived from the core endophytic microbiome of hyperaccumulators and their role in cadmium phytoremediation

BACKGROUND

Although numerous endophytic bacteria have been isolated and characterized from cadmium (Cd) hyperaccumulators, the contribution and potential application of the core endophytic microbiomes on facilitating phytoremediation were still lack of intensive recognition. Therefore, a 2-year field sampling in different location were firstly conducted to identify the unique core microbiome in Cd hyperaccumulators, among which the representative cultivable bacteria of different genera were then selected to construct synthetic communities (SynComs). Finally, the effects and mechanisms of the optimized SynCom in regulating Cd accumulation in different ecotypes of Sedum alfredii were studied to declare the potential application of the bacterial agents based on core microbiome.

RESULTS

Through an innovative network analysis workflow, 97 core bacterial taxa unique to hyperaccumulator Sedum was identified based on a 2-year field 16S rRNA sequencing data. A SynCom comprising 13 selected strains belonging to 6 different genera was then constructed. Under the combined selection pressure of the plant and Cd contamination, Alcaligenes sp. exhibited antagonistic relationships with other genera and plant Cd concentration. Five representative strains of the other five genera were further conducted genome resequencing and developed six SynComs, whose effects on Cd phytoremediation were compared with single strains by hydroponic experiments. The results showed that SynCom-NS comprising four strains (including Leifsonia shinshuensis, Novosphingobium lindaniclasticum, Ochrobactrum anthropi, and Pseudomonas izuensis) had the greatest potential to enhance Cd phytoremediation. After inoculation with SynCom-NS, genes related to Cd transport, antioxidative defense, and phytohormone signaling pathways were significantly upregulated in both ecotypes of S. alfredii, so as to promote plant growth, Cd uptake, and translocation.

CONCLUSION

In this study, we designed an innovative network analysis workflow to identify the core endophytic microbiome in hyperaccumulator. Based on the cultivable core bacteria, an optimized SynCom-NS was constructed and verified to have great potential in enhancing phytoremediation. This work not only provided a framework for identifying core microbiomes associated with specific features but also paved the way for the construction of functional synthetic communities derived from core microbiomes to develop high efficient agricultural agents. Video Abstract.

Microbiomes of urban trees: unveiling contributions to atmospheric pollution mitigation

Urban trees are crucial in delivering essential ecosystem services, including air pollution mitigation. This service is influenced by plant associated microbiomes, which can degrade hydrocarbons, support tree health, and influence ecological processes. Yet, our understanding of tree microbiomes remains limited, thus affecting our ability to assess and quantify the ecosystem services provided by trees as complex systems. The main hypothesis of this work was that tree microbiomes concur to hydrocarbon biodegradation, and was tested through three case studies, which collectively investigated two tree micro-habitats (phyllosphere and tree cavity organic soil-TCOS) under various conditions representing diverse ecological scenarios, by applying different culture-based and molecular techniques and at different scales. The integration of all results provided a more comprehensive understanding of the role of microbiomes in urban trees. Firstly, bacterial strains isolated from the phyllosphere of Quercus ilex were characterized, indicating the presence of Plant-Growth Promoting bacteria and strains able to catabolize PAHs, particularly naphthalene and phenanthrene. Secondly, naphthalene biodegradation on artificially spiked Hedera helix leaves was quantified in greenhouse experiments on inoculated and untreated plants. The persistence of the inoculated strain and community structure of epiphytic bacteria were assessed by Illumina sequencing of V5-V6 hypervariable regions of 16S rRNA gene. Results showed that naphthalene degradation was initially faster on inoculated plants but later the degradation rates became similar, probably because bacterial populations with hydrocarbon-degrading abilities gradually developed also on non-inoculated plants. Finally, we explored bacterial and fungal biodiversity hosted by TCOS samples, collected from six large trees located in an urban park and belonging to different species. Microbial communities were characterized by Illumina sequencing of V5-V6 hypervariable regions of bacterial gene 16S rRNA and of fungal ITS1. Results indicated TCOS as a distinct substrate, whose microbiome is determined both by the host tree and by canopy environmental conditions and has a pronounced aerobic hydrocarbon degradation potential. Overall, a better assessment of biodiversity associated with trees and the subsequent provision of ecosystem services constitute a first step toward developing future new microbe-driven sustainable solutions, especially in terms of support for urban green planning and management policy.

Dynamic responses of soil microbial communities to seasonal freeze-thaw cycles in a temperate agroecosystem

Soil freeze-thaw cycles (FTCs) are common in temperate agricultural ecosystems during the non-growing season and are progressively influenced by climate change. The impact of these cycles on soil microbial communities, crucial for ecosystem functioning, varies under different agricultural management practices. Here, we investigated the dynamic changes in soil microbial communities in a Mollisol during seasonal FTCs and examined the effects of stover mulching and nitrogen fertilization. We revealed distinct responses between bacterial and fungal communities. The dominant bacterial phyla reacted differently to FTCs: for example, Proteobacteria responded opportunistically, Actinobacteria, Acidobacteria, Choroflexi and Gemmatimonadetes responded sensitively, and Saccharibacteria exhibited a tolerance response. In contrast, the fungal community composition remained relatively stable during FTCs, except for a decline in Glomeromycota. Certain bacterial OTUs acted as sensitive indicators of FTCs, forming keystone modules in the network that are closely linked to soil carbon, nitrogen content and potential functions. Additionally, neither stover mulching nor nitrogen fertilization significantly influenced microbial richness, diversity and potential functions. However, over time, more indicator species specific to these agricultural practices began to emerge within the networks and gradually occupied the central positions. Furthermore, our findings suggest that farming practices, by introducing keystone microbes and changing interspecies interactions (even without changing microbial richness and diversity), can enhance microbial community stability against FTC disturbances. Specifically, higher nitrogen input with stover removal promotes fungal stability during soil freezing, while lower nitrogen levels increase bacterial stability during soil thawing. Considering the fungal tolerance to FTCs, we recommend reducing nitrogen input for manipulating bacterial interactions, thereby enhancing overall microbial resilience to seasonal FTCs. In summary, our research reveals that microbial responses to seasonal FTCs are reshaped through land management to support ecosystem functions under environmental stress amid climate change.

Flue-cured tobacco intercropping with insectary floral plants improves rhizosphere soil microbial communities and chemical properties of flue-cured tobacco

BACKGROUND

Continuous cropping of the same crop leads to land degradation. This is also called the continuous-cropping obstacle. Currently, intercropping tobacco with other crops can serve as an effective strategy to alleviate continuous cropping obstacles.

RESULTS

In this study, tobacco K326 and insectary floral plants were used as materials, and seven treatments of tobacco monoculture (CK), tobacco intercropped with Tagetes erecta, Vicia villosa, Fagopyrum esculentum, Lobularia maritima, Trifolium repens, and Argyranthemum frutescens respectively, were set up to study their effects on rhizosphere soil chemical properties and composition and structure of rhizosphere soil microbial community of tobacco. The 16 S rRNA gene and ITS amplicons were sequenced using Illumina high-throughput sequencing. tobacco/insectary floral plants intercropping can influence rhizosphere soil chemical properties, which also change rhizosphere microbial communities. The CK and treatment groups tobacco rhizosphere soil microorganisms had significantly different genera, such as tobacco intercropping with T. repens and A. frutescens significantly increased the number of Fusarium and intercropping T. erecta, V. villosa, L. maritima, T. repens, and A. frutescens significantly increased the number of Sphingomonas and unknown Gemmatimonadaceae. Additionally, intercropping T. erecta, V. villosa and L. maritima changed the rhizosphere fungal and bacteria community and composition of tobacco and the positive correlation between tobacco rhizosphere the genera of fungi and bacterial were greater than CK. The pathway of the carbohydrate metabolism, amino acid metabolism, and energy metabolism in rhizosphere bacteria were significantly decreased after continuous cropping. Fungal symbiotic trophic and saprophytic trophic were significantly increased after intercropping V. villosa, L. maritima and plant pathogen and animal pathogen were increased after intercropping T. repens and A. frutescens. Additionally, bacterial and fungal communities significantly correlated with soil chemical properties, respectively.

CONCLUSION

This study reveals that intercropping tobacco with insectary floral plants, particularly T. erecta, V. villosa, L. maritima and A. frutescens significantly affects soil chemical properties and alters rhizosphere microbial communities, increasing the abundance of certain microbial genera. Additionally, intercropping enhances pathways related to carbohydrate, amino acid, and energy metabolism in rhizosphere bacteria. These findings suggest that intercropping could provide a promising strategy to overcome challenges associated with continuous tobacco cropping by regulating the rhizosphere environment.

Research on the optimal ratio of improved electrolytic manganese residue substrate about Pennisetum sinese Roxb growth effects

Electrolytic manganese slag (EMR) is a solid waste generated in the manganese hydrometallurgy process. It not only takes up significant land space but also contains Mn2+, which can lead to environmental contamination. There is a need for research on the treatment and utilization of EMR. Improved EMR substrate for Pennisetum sinese Roxb growth was determined in pot planting experiments. The study tested the effects of leaching solution, microorganisms, leaf cell structures, and growth data. Results indicated a substrate of 45% EMR, 40% phosphogypsum, 5% Hericium erinaceus fungi residue, 5% quicklime, and 5% dolomite sand significantly increased the available phosphorus content (135.54 ± 2.88 μg·g-1) by 17.95 times, compared to pure soil, and enhanced the relative abundance of dominant bacteria. After 240 days, the plant height (147.00 ± 0.52 cm), number of tillers (6), and aerial dry weight (144.00 ± 15.99g) of Pennisetum sinese Roxb increased by 5.81%, 200%, and 32.58%, respectively. Analyses of leaves and leaching solution revealed that the highest leaf Mn content (46.84 ± 2.91 μg·g-1) being 3.38 times higher than in pure soil, and the leaching solution Mn content (0.66 ± 0.13 μg·g-1) was lowest. Our study suggested P. sinese Roxb grown in an improved EMR substrate could be a feasible option for solidification treatment and resource utilization of EMR.

The addition of humic acid into soil contaminated with microplastics enhanced the growth of black gram (Vigna mungo L. Hepper) and modified the rhizosphere microbial community

Microplastics have polluted agricultural soils, posing a substantial risk to crop productivity. Moreover, the presence of microplastic pollution has caused a disturbance in the composition of the microbial community in the soil surrounding plant roots, therefore impacting the growth of beneficial bacteria. A study was conducted to examine if humic acid (HA) can counteract the harmful effects of microplastics (MPs) on the growth of black gram crops and the composition of the rhizosphere soil microbial community, to reduce the negative impacts of microplastics on these microorganisms and crops. The research was carried out using mud pots and the plastic utilized for the experiment consisted of 60% high-density polyethylene (HDPE) and 40% polypropylene (PP). The soil was enriched with lignite-based potassium humate, which had a pH range of 8.0-9.5 and with 65% humic acid. The experiment consisted of six treatments: T1, which served as the control without HA and MP; T2, which involved the use of HA at a concentration of 0.15% w/w; T3, which involved the use of MP at a concentration of 0.2% w/w; T4, which involved the use of MP at a concentration of 0.4% w/w; T5, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.2% w/w; and T6, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.4% w/w. The plant growth characteristics, including germination percentage, nodule number, and chlorophyll content, were measured. In addition, the DNA obtained from the rhizosphere soil was analyzed using metagenomics techniques to investigate the organization of the microbial population. Seedlings in soil polluted with MP exhibited delayed germination compared to seedlings in uncontaminated soil. Following 60 days of growth, the soil samples treated with T5 (0.2% MP and 0.15% HA w/w) had the highest population of bacteria and rhizobium, with counts 5.58 ± 0.02 and 4.90 ± 0.02 CFU g-1 soil. The plants cultivated in T5 had the most elevated chlorophyll-a concentration (1.340 ± 0.06 mg g-1), and chlorophyll-b concentration (0.62 ± 0.02 mg g-1) while those cultivated in T3 displayed the lowest concentration of chlorophyll-a (0.59 ± 0.02 mg g-1) and chlorophyll-b (0.21 ± 0.04 mg g-1). Within the phylum, Proteobacteria had the highest prevalence in all treatments. However, when the soil was polluted with MPs, its relative abundance was reduced by 8.4% compared to the control treatment (T1). Conversely, treatment T5 had a 3.76% rise in relative abundance when compared to treatment T3. The predominant taxa found in soil polluted with MP were Sphingomonas and Bacillus, accounting for 19.3% of the total. Sphingomonas was the predominant genus (21.2%) in soil polluted with MP and supplemented with humic acid. Humic acid can be used as a soil amendment to mitigate the negative effects of MPs and enhance their positive advantages. Research has demonstrated that incorporating humic acid into soil is a viable method for maintaining the long-term integrity of soil's physical, chemical, and biological characteristics.

A potential bioaerosol source from kitchen chimneys in restaurants

Bioaerosols are ubiquitous and have a substantial impact on the atmosphere and human health. Despite the identification of numerous bioaerosol emission sources, the contribution of anthropogenic sources remains inadequately understood. In kitchens, oil stains accumulated at the vent may discharge microorganisms into the environment with airflow, potentially discharging bioaerosol pollution. This putative anthropogenic source of bioaerosols has been long ignored. To investigated whether kitchen chimneys can be a potential source for bioaerosols, air samples, oil stains from in/out chimneys, and surface sand samples were collected near several commercial restaurants. PCoA showed that sampling sites significantly impacted microbiomes, whereas SourceTracker analysis led to the finding that waste grease significantly contributed to bioaerosol composition. Both findings agree with the kitchen chimney as a source of microbes in bioaerosols in the surrounding environment. Furthermore, despite the low biodiversity, a high proportion of stress-tolerant and potential pathogenic bacteria and fungi were found in residual culinary grease, which may escape into the air causing potential risks to human beings. These results led to the proposal that airborne microbiota can originate from cooking waste grease. Immediate actions should be taken into account to enhance disinfection and sterilization aimed at fume vents.

Vaginal microbiota in term pregnant women with differences in cervical ripeness revealed by 2bRAD-M

BACKGROUND

Cervical ripening is a multifactorial outcome, and the association between cervical ripening and vaginal microbiota remains unexplored in term primiparous women. A new sequencing technology, microbiome 2bRAD sequencing (2bRAD-M) that provides a higher level of species discrimination compared to amplicon sequencing. We applied 2bRAD-M to analyze the vaginal microbiota in a population with variations in cervical ripeness and to explore potential microbiota factors influencing cervical ripening.

METHODS

A total of 30 full-term primigravid women participated in this study, with 15 belonging to the low scoring group of cervical ripeness and 15 to the high scoring group. Clinical information was collected from the participants, and the vaginal microbiota and community structure of both groups were analyzed using 2bRAD-M sequencing. Microbiota diversity and differential analyses were conducted to explore potential factors influencing cervical ripening.

RESULTS

A total of 605 species were detected. There was no difference in vaginal microbiota diversity between the two groups, and the vaginal microbial composition was structurally similar. In the two groups, Lactobacillus crispatus and Lactobacillus iners were identified as the two pivotal species through random forest analysis. Concurrent, extensive and close connections between species within the two groups were observed in the correlation analysis, influencing the aforementioned two species. Pairwise comparisons showed that Sphingomonas (P = 0.0017) and three others were abundant in high scoring group, while Alloprevotella (P = 0.0014), Tannerella (P = 0.0033), Bacteroides (P = 0.0132), Malassezia (P = 0.0296), Catonella (P = 0.0353) and Pseudomonas (P = 0.0353) and so on showed higher abundance in low scoring group. Linear discriminant analysis effect size identified 29 discriminative feature taxa.

CONCLUSION

For the first time, vaginal microbiota was sequenced using 2bRAD-M. With a relatively simple structure, a more stable vaginal microbiota is associated with higher cervical ripeness, and certain microorganisms, such as Sphingomonas, may play a beneficial role in cervical ripening.