Mycobiome diversity: high-throughput sequencing and identification of fungi

The impact of rhizosphere soil microorganisms on the medicinal active ingredients of Atractylodes chinensis from different regions

AIMS

Analyzing the rhizosphere microbial community structure of Atractylodes chinensis from different regions and its correlation with the accumulation of main medicinal active ingredients, this study aims to explore the impact of rhizosphere soil microorganisms on the effective components of A. chinensis, providing a scientific basis for the high-quality and high-yield cultivation of A. chinensis.

METHODS AND RESULTS

The rhizosphere soil of three-year-old A. chinensis was used as the research object. High-throughput sequencing technology was employed to analyze the rhizosphere bacterial and fungal community structures. High Performance Liquid Chromatography (HPLC) was used to detect the contents of atractylodin, atractylon, β-eudesmol, and atractylenolide III in the medicinal materials. Pearson correlation analysis was performed to explore the relationship between soil microbial communities and the active ingredients. α-diversity results showed that the Yaowangmiao village (YWM) microbial community had the highest richness and diversity, while Xingzhoucun (XZC) had the lowest, and Beiwushijiazi village (BWSJZ) had the lowest fungal community diversity and richness. PCoA analysis at the phylum level indicated that soil bacterial communities were more dispersed than fungal communities among different regions. The bacterial community in XZC significantly differed from other regions, while fungal communities in BWSJZ and Ximiaogong village (XMG) showed considerable differences from other regions. The content of active ingredients in different regions showed that Yuzhangzi village (YZZ) and BWSJZ had higher content and better quality of medicinal materials according to the content of atractylodesin specified in the Chinese Pharmacopoeia Commission. The dominant bacterial phylum in the rhizosphere soil of YZZ was Acidobacteriota, and the dominant genus was RB41. In BWSJZ, Acidobacteriota was the dominant bacterial phylum, with Arthrobacter and unclassified_f_Vicinamibacteraceae as dominant genera; the dominant fungal phylum was Basidiomycota, with Tausonia as the dominant genus. Different bacterial and fungal communities synergistically promoted or inhibited the synthesis of four active ingredients.

CONCLUSION

In short, this provides a theoretical basis for the distribution of soil rhizosphere microbial communities in the cultivation of A. chinensis and offers a reference for the cultivation of A. chinensis medicinal materials.

Integrated transcriptome and DNA methylome analysis reveal the browning mechanism in Agaricus bisporus

The white button mushroom (Agaricus bisporus), widely cultivated worldwide as an edible mushroom, is susceptible to browning, which significantly impacts its nutritional and commercial value. Extensive research has enhanced our understanding of the mechanisms underlying this browning process. Although the role of DNA methylation in regulating gene expression has been studied in many fungi, information specifically concerning DNA methylation during the browning in A. bisporus is still limited. In this study, we initially evaluated the impact of temperatures (4 ℃ and room temperature) on discoloration in A. bisporus, and samples with similar discoloration under different temperatures were collected for transcriptome and DNA methylation sequencing. The results revealed that DNA methylation was positively correlated with browning, suggesting its involvement during the browning in A. bisporus. Further analysis showed the heightened methylation levels were primarily attributed to increased methylation at CHG and CHH sites. By joint analysis of transcriptome and DNA methylome, 342 genes with significant expression changes were identified to be affected by DNA methylation, and finally 13 genes were considered as important browning genes under different signaling pathways, such as ABA/ET pathway. Notably, four DNA methyltransferases were identified and validated to play important role during browning in A. bisporus. Altogether, this study provides theoretical insights into the functions of DNMTs in A. bisporus, and offers new perspectives on the role of DNA methylation in edible mushrooms.

Uncharacterized members of the phylum Rozellomycota dominate the fungal community of a full-scale slow sand filter for drinking water production

Slow sand filters (SSFs) for drinking water production are habitats for diverse microbes from multiple domains of life, which are integral to the ability of SSFs to purify water. While cultivation-independent analyses of the prokaryotic communities of SSFs have provided valuable insights, little attention has been paid to fungi inhabiting SSFs. This study characterized the fungal communities in the sand biofilm of one established, one inoculated and one non-inoculated SSF. The removal of the top-layer of sand ("scraping") allowed fungal communities in the top and subsurface layers of sand to be analyzed using amplicon sequencing of the ITS2 region of fungal rRNA genes. The top layers of SSF sand contained fungal communities dominated by phylum Ascomycota (43.5-75.6 %). After scraping, high abundances (>70 %) of phylum Rozellomycota were revealed in the established filter. These fungi were also detected in an inoculated filter, but not in a non-inoculated filter, suggesting potential dispersal to new filters by inoculation. The diverse Rozellomycota sequences potentially represented 6 different order-level clades, with most being related to previously observed Branch03 Rozellomycota. Their roles in SSF function are unknown but may be related to the removal of indicator bacteria as this phylum includes potential parasites of grazing eukaryotes. Fungi known to constitute microbial risk or contribute to micropollutant biodegradation were in low abundance and only sporadically detected. Lifestyle traits could be predicted for 61.8 % of fungi in the SSF biofilm; most of these were saprotrophic microfungi or yeasts. This study presents an overview of the composition of fungal communities in full-scale SSF, and their potential interactions with water quality. It also highlights the need for more knowledge regarding the ecology of "dark matter"-fungi, such as Rozellomycota, and presents an accessible and societally relevant environment for future research of these microbes.

Emerging technologies for pollinator monitoring

Efficient tools for monitoring pollinator populations are urgently needed to address their reported declines. Here, we review advanced technologies focusing on image recognition and DNA-based methods to monitor bees, hoverflies, moths, and butterflies. Insect camera traps are widely used to record nocturnal insects against uniform backgrounds, while cameras studying diurnal pollinators in natural vegetation are in early stages of development. Depending on context, insect camera traps can assess occurrence, phenology, and proxies of abundance for easily recognisable and common species. DNA-based techniques can drastically decrease the costs of sample processing and speed of specimen identification but strongly depend on the completeness of reference DNA databases, which are continually improving. Molecular analyses are becoming more affordable as uptake increases. Image-based methods for identification of dead specimens show promising results for some invertebrates, but image reference databases for pollinators are far from complete. Building image reference databases with expert entomologists is a priority. Lidar and acoustic sensors are emerging technologies although it is still uncertain which insect taxa can be separated in data from these sensors and how well. By improving accessibility to novel technologies and integrating them with existing approaches, monitoring of pollinators and other insects could deliver richer, more standardised and possibly cheaper data with benefits to future insect conservation efforts.

Assessing population exposure to airborne fungi in the UK over one year using high-throughput sequencing (HTS) metabarcoding methods

Airborne fungi are significant contributors to allergic and infectious disease. While microscopy remains the primary method for fungal identification, high-throughput sequencing (HTS) enables untargeted analysis of a much wider range of environmental taxa. This study used HTS to better characterise airborne fungal composition over a 12-month period in two UK locations, the city of Leicester in central England and a rural site in Chilton (Oxfordshire) approximately 115 km further south. Air samples were collected over a year. A subset of 240 samples (120 per location) were analysed by HTS with a combined internal transcribed spacer region (ITS2) and D1/D2 region of the large subunit (LSU) metabarcoding approach. With statistical imputation a representative 12-month dataset was created. Differences in fungal diversity and composition were explored, incorporating meteorological data. HTS analysis identified 272 fungal genera across locations and seasons, approximately 4-fold more than in other studies using traditional microscopy methods. Fungal diversity, richness and composition at the two locations were broadly similar with some taxa-specific differences likely reflecting land-use types (urban vs rural) and/or local meteorological variables. In particular, air temperature and precipitation significantly influenced fungal composition. This study demonstrates the value of HTS for characterising airborne fungi. While it does not provide absolute quantitation, HTS could be used as a screening tool to identify novel associations between fungal exposure and health outcomes, and should be used in combination with quantitative methods, such as microscopy and quantitative PCR (qPCR). Greater spatial and temporal understanding of the wide range of airborne fungal exposure is crucial for exploring associated health impacts and developing improved public health interventions and alert systems for susceptible individuals.

Mycobiome of Pinus pinaster trees naturally infected by the pinewood nematode Bursaphelenchus xylophilus

Fungi are important biological elements in the Pine wilt disease (PWD) complex. In the late stages of the disease, the pinewood nematode (PWN) Bursaphelenchus xylophilus feeds on the fungal flora available in the pine tree for survival and multiplication. Previous studies have confirmed a close relation between the PWN and blue-stain fungi (Ophiostomatales), which are necrotrophic pathogens associated with bark beetles (Coleoptera: Scolytidae). The PWN is able to grow densely in the presence of these fungi, which results in a higher number of nematodes transferred to the insect-vector Monochamus spp. To understand the spatial diversity and structure of Pinus pinaster mycobiome, wood samples from PWN-infected and non-infected pine trees were collected in three locations of Continental mainland Portugal with different PWD records, during the maturation phase of the insect-vector M. galloprovincialis (winter 2019-spring 2020). The PWN-mycobiome from the PWN-infected P. pinaster was also characterized. A total of 27 samples of P. pinaster and 13 samples of PWN from PWN-infected trees were characterized using ITS2 amplicon sequencing. The diversity and structure of the fungal communities in P. pinaster varied with disease status suggesting that the PWN presence affects the endophytic fungal communities. For both P. pinaster and PWN fungal communities, differences were also associated with locations (recent PWD loci Seia, and long-term PWN locus Companhia das Lezírias and Tróia). Ophiostomatales were mainly detected in PWN-infected P. pinaster. This research contributes to increase the knowledge on the ecology of the fungal communities in PWD complex.

PCR bias in 16S rRNA genes caused by GC content leads to insufficient detection of some abundant species in amplicon sequencing analyses of thermophilic microbial communities

Amplicon sequencing is a widely used method for surveying biological diversity. However, the technique is disturbed by PCR bias leading to errors in community composition analyses. In this study, microbial community composition was evaluated in twenty-eight locations of hot spring water with temperatures between 87-48°C at Nakabusa Hot Springs, Japan, using amplicon sequencing analysis with the V4 region of the 16S rRNA gene. In discrepancy with the greenish color and the absorption spectra of the microbial samples, the relative abundance of amplicon sequence variants (ASVs) in the major photosynthetic organisms, Chloroflexus spp., were scarce in any sample when using the annealing temperature of 50°C in amplicon PCR. Changing the annealing temperature to 68ºC significantly improved the detection efficiency of Chloroflexus ASVs, and the obtained numbers were consistent with the presence of the photosynthetic pigments. The abundance of many other microbial ASVs was also dependent on the annealing temperature. The log ratio in the abundance of major ASVs between two annealing temperatures was correlated with the GC content of the 16S rRNA gene, suggesting that even some other major ASVs in the community are seriously affected by PCR bias due to the GC content. Combined usage of results from two different annealing temperatures, rather than a result using a single annealing temperature, seems to be a better way to obtain community structure information with less PCR bias in thermophilic organisms of high 16S rRNA GC content.

Metabarcoding with Illumina and Oxford Nanopore Technologies provides complementary insights into tree seed mycobiota

BACKGROUND

Culturing of fungi is labor-intensive and reveals limited diversity, while high-throughput sequencing of barcodes (i.e., metabarcoding) enables a simultaneous detection of fungi from multiple environmental samples. Metabarcoding using short-read sequencers, such as Illumina platforms, provides high sequencing depths but results in many unidentified taxa. Long-read sequencing can improve species and genus assignments but might encompass lower sequencing depth and limit diversity coverage. In this study, fungi in seeds of eleven angiosperm and gymnosperm tree species were assessed using traditional culturing, Illumina short-read metabarcoding, and Oxford Nanopore Technologies long-read metabarcoding. We focused on seed-borne fungi as understanding their diversity and potential impacts on seedlings is crucial for securing plant health. We compared (1) the number and identity of fungal genera and species between metabarcoding approaches and traditional culturing and (2) fungal alpha- and beta-diversity between metabarcoding methods, considering different hosts and fungal lifestyles.

RESULTS

In both short- and long-read metabarcoding datasets, similar numbers of fungal reads and operational taxonomic units were assigned to comparable numbers of fungal genera and species. About one-third of the identified genera were plant pathogens, followed by saprotrophs and endophytes. Culturing overall revealed fewer fungal genera, while most of the fungal reads in short-read metabarcoding datasets stemmed from cultured taxa. Long-read metabarcoding revealed lower per-sample diversity than short-read metabarcoding and distinct fungal communities compared to those from the short-read datasets. Host-dependent patterns in alpha- and beta-diversity were observed across methods, with angiosperms harboring more fungal taxa than gymnosperms, and distinct community structuring across host tree groups and species, although the differences were stronger in short-read than long-read metabarcoding datasets.

CONCLUSIONS

Illumina and Oxford Nanopore Technologies metabarcoding captured similar host-dependent diversity patterns despite observed differences in numbers and composition of fungi. Short-read metabarcoding might be optimal for fungal biodiversity studies due to higher sequencing depths and resultant breadth of diversity. As error rates are continuing to decrease, reference databases expand, and throughput improves, long-read metabarcoding is becoming a strong candidate for future diagnostic studies of fungi. Traditional culturing captures most of the fungi from short-read metabarcoding and remains valuable for obtaining isolates for further research.

Changes in the assembly and functional adaptation of endophytic microbial communities in Amorphophallus species with different levels of resistance to necrotrophic bacterial pathogen stress

Pcc is one of the key pathogenic factors responsible for destructive soft rot in konjac. To date, the assembly and functional adaptation of the plant endophytic microbiome under Pcc stress remain poorly understood. Here, we found that Pcc stress leads to rapid reorganization of the endogenous microbiome in multiple organs of both susceptible and resistant konjac plants. Under Pcc stress, the negative interactions within the bacterial-fungal interdomain network intensified, suggesting an increase in ecological competition between bacterial and fungal taxa. We further discovered that the relative abundance dynamics of the classes Dothideomycetes and Sordariomycetes, as core fungal taxa, changed in response to Pcc stress. By isolating culturable microorganisms, we demonstrated that 46 fungal strains strongly inhibited the growth of Pcc. This implies that endophytic fungal taxa in konjac may protect the host plant through ecological competition or by inhibiting the growth of pathogenic bacteria. Metagenomic analysis demonstrated that microbial communities associated with resistant Amorphophallus muelleri exhibited unique advantages over susceptible Amorphophallus konjac in enhancing environmental adaptability, regulating plant immune signaling, strengthening cell walls, and inducing defense responses. Our work provides important evidence that endophytic fungal taxa play a key role in the host plant's defense against necrotizing bacterial pathogens.

Whole-genome sequencing of the first Candida auris clinical isolate from a patient with sepsis in Palestine

An isolate of the multidrug-resistant yeast Candida auris (Pal1) was identified in the urine of a patient with sepsis and sequenced using both Oxford Nanopore and Illumina sequencing technologies. Phylogenetic analysis placed C. auris Pal1 in the geographical Clade I, with distinct SNPs linked to azole resistance (Erg11Y132F and Mrr1T647N).

Inter-kingdom interactions and environmental influences on the oral microbiome in severe early childhood caries

Dental caries arise from intricate interactions among oral microorganisms, impacting ecological stability and disease progression. In this study, we aimed to investigate the microbial diversity and inter-kingdom interactions in severe early childhood caries (S-ECC) and assess the influence of environmental factors such as salivary pH and trace elements. We analyzed 61 children aged 3-4 years with complete deciduous dentition, evaluating salivary pH, buffering capacity, and trace elements (iron, fluoride). We examined the performance of 16S rRNA V1-V9 regions gene and internal transcribed spacer (ITS) primers for bacteria and fungi from plaque and saliva to characterize community compositions and diversity. Findings revealed significant shifts in bacterial diversity in S-ECC saliva samples, marked by decreased diversity and elevated abundance of cariogenic species, particularly Streptococcus mutans. Candida albicans was notably more prevalent in the S-ECC group, implicating its potential role in pathogenesis. Iron and fluoride concentrations showed no significant correlation with microbial community structure. Network analyses uncovered complex intra- and inter-kingdom interactions, underscoring cooperative and competitive dynamics. S-ECC children exhibited higher abundances of bacteria (Streptococcus mutans, Granulicatella, Actinomyces) and fungi (Candida albicans), with specific microbial taxa associated with reduced salivary pH.

IMPORTANCE

This study illuminates the intricate relationship between bacteria and fungi within the oral microbial community of children, specifically highlighting differences between those with S-ECC and those without caries. Through an extensive analysis of the microbial composition in both saliva and dental plaque, we identified a significant increase in the abundance of specific bacterial taxa (e.g., S. mutans, Granulicatella, Actinomyces) and fungal species (e.g., C. albicans) in the oral cavities of children with S-ECC. This finding underscores the potential role of these microorganisms in the development of caries. Contrary to previous studies that emphasize the importance of iron and fluoride in oral health, our research found no significant correlation between the concentrations of these elements and the composition of oral microbial communities. This result challenges conventional understanding and opens new avenues for future research. Additionally, our findings revealed an association between Veillonella sp., Propionibacterium sp., and Candida sp. and reduced salivary pH. This provides novel insights into the relationship between the oral microenvironment and caries development. The implications of our findings are substantial for the development of prevention and intervention strategies targeting childhood caries. They also underscore the critical need for a deeper exploration of oral microbial interactions and their environmental influences.

Impact of agricultural systems on arbuscular mycorrhizal fungi community composition in robusta coffee roots in the Democratic Republic of congo

Robusta coffee, grown by 25 million farmers across more than 50 countries, plays an important role in smallholder farmers' livelihoods and the economies of many low-income countries. Coffee establishes a mutualistic symbiosis with arbuscular mycorrhizal fungi (AMF); however, the impact of agricultural practices and soil characteristics on AMF diversity and community composition is not well understood. To address this, we characterised the AMF community composition of robusta coffee in part of its region of origin, the Democratic Republic of Congo. AMF diversity and community composition were compared between coffee monoculture, agroforestry systems and wild robusta in its native rainforest habitat. Using Illumina sequencing on 304 root samples, we identified 307 AMF operational taxonomic units (OTUs), dominated by the genera Glomus and Acaulospora. OTU richness did not vary across the three studied systems, yet large differences in community composition were found. Many unique OTUs were only observed in the coffee in the rainforest. In general, lower available soil phosphorus (P) and lower soil bulk density increased AMF diversity, yet higher available soil P and pH increased AMF diversity in the wild forest coffee. Shifts in AMF community composition across coffee systems were driven by canopy closure, soil pH, available soil P and soil bulk density. Our study is the first to characterise mycorrhizal communities in wild robusta coffee in its region of origin and shows that even low-input agricultural practices result in major AMF community shifts as compared to a natural baseline.

FunVIP: Fungal Validation and Identification Pipeline based on phylogenetic analysis

The increase of sequence data in public nucleotide databases has made DNA sequence-based identification an indispensable tool for fungal identification. However, the large proportion of mislabeled sequence data in public databases leads to frequent misidentifications. Inaccurate identification is causing severe problems, especially for industrial and clinical fungi, and edible mushrooms. Existing species identification pipelines require separate validation of a dataset obtained from public databases containing mislabeled taxonomic identifications. To address this issue, we developed FunVIP, a fully automated phylogeny-based fungal validation and identification pipeline (https://github.com/Changwanseo/FunVIP). FunVIP employs phylogeny-based identification with validation, where the result is achievable only with a query, database, and a single command. FunVIP command comprises nine steps within a workflow: input management, sequence-set organization, alignment, trimming, concatenation, model selection, tree inference, tree interpretation, and report generation. Users may acquire identification results, phylogenetic tree evidence, and reports of conflicts and issues detected in multiple checkpoints during the analysis. The conflicting sample validation performance of FunVIP was demonstrated by re-iterating the manual revision of a fungal genus with a database with mislabeled sequences, Fuscoporia. We also compared the identification performance of FunVIP with BLAST and q2-feature-classifier with two mass double-revised fungal datasets, Sanghuangporus and Aspergillus section Terrei. Therefore, with its automatic validation ability and high identification performance, FunVIP proves to be a highly promising tool for achieving easy and accurate fungal identification.

Discovering the dynamics of peach fruit mycobiome throughout fruit development season by high-throughput sequencing

The mycobiome is comprised of a rich array of fungal species that compete for resources, and species diversity and prevalence exhibit a dynamic structure under the influence of many factors. While the host fruit develops, the prevalence and the arrangement of fungal species in this mycobiome also change, forming a dynamic microenvironment. In this study, fungal diversity on peach fruit surfaces at different developmental stages have been determined to better understand the changes in fungal diversity and disease occurrence by using metabarcoding of the full ITS region and processing the obtained high-throughput sequencing data with various bioinformatic analyses. It has been found that fungal diversity in early developmental stages is higher, and the diversity declines as the fruit matures, likely due to more prevalent fungal species establishing themselves on the surface as the fruit develops. Additionally, this research reveals that the prevalence of pathogens does not necessarily mean that disease will develop, as pathogenic species were found to be at higher prevalence percentages when compared to non-pathogenic species in healthy fruit samples. This study also identified the Monilinia polystroma species at a molecular level for the first time in Türkiye; however, no symptomatic signals were recorded on the host. The study provides valuable data for mycobiome studies, while also highlighting its importance in optimizing sustainable disease management strategies.

Microbial decay of wooden structures: actors, activities and means of protection

Wood decay fungi and bacteria play a crucial role in natural ecosystems, contributing to the decomposition of lignocellulosic materials and nutrient cycling. However, their activity poses significant challenges in timber durability, impacting industries reliant on wood as a construction material. This review examines the diversity of microorganisms damaging timber used indoors and outdoors. Additionally, traditional and advanced methods for microbial identification are discussed, with a focus on DNA-based, culture-independent sequencing methods whose importance has increased massively in recent years. It also provides an overview of the various options for wood protection, starting from wood protection by design, to chemical wood preservation and wood modification methods. This should illustrate how important it is to combine an ecological understanding of the decay organisms, precise identification and innovative wood protection methods in order to achieve a long-term and thus resource-saving use of wood. KEY POINTS: • Fungi and bacteria play a crucial role in the decomposition of timber wood. • Traditional and advanced DNA-based methods for microbial identification are discussed. • An overview of the various options for wood protection is provided.

FungID: Innovative Fungi Identification Method with Chromogenic Profiling of Colony Color Patterns

Fungi play crucial roles in many ecosystems; however, traditional identification methods are often time- and labor-intensive. In this study, we introduce FungID, a pilot and novel deep learning algorithm, alongside its user-friendly software implementation, developed by analyzing various fungal species for identification based on chromogenic profiling of colony color patterns via a Convolutional Neural Network. Training and testing FungID upon a set of 269 images showed remarkable performance in terms of model robustness and classification efficacy. These findings demonstrate that FungID offers a potential method for rapid and reliable identification of fungal species through chromogenic profiling, providing additional tools to conventional techniques being employed in the fields of health, microbiology, biotechnology, and more. Our research underscores the promising role of deep learning algorithms in enhancing the understanding of the taxonomy and ecological functions of fungi that can be grown in pure cultures, while also emphasizing the importance of carefully assessing the scope and limitations of these methods.

Identification and comparative genomic analysis of endophytic fungi in Bletilla striata and its potential for promoting militarine bioaccumulation

Bletilla striata (Thunb.) Reichb.f is renowned for its traditional medicinal applications and a spectrum of pharmacological activities, which is intricately linked to militarine. Addressing sustainable production of B. striata and militarine necessitates innovative strategies. Endophytic fungi, residing within plant tissues and establishing symbiotic relationships, act as secondary genomes of plants, co-regulating plant growth and secondary metabolite synthesis. Despite their potential, the genetic and metabolic diversity, functional activity, and regulatory interactions of endophytic fungi with B. striata remain unexplored. This study aims to bridge this gap by investigating endophytic fungi that could enhance B. striata growth and militarine biosynthesis. The study revealed that endophytic fungi from pseudobulbs, roots, and stems were co-cultured with callus tissue of B. striata, and it was discovered that Serendipita indica from the Serendipita genus can enhance militarine accumulation. Subsequently, key genes, core enzymes, and regulatory factors related to militarine biosynthesis in the S. indica genome were analyzed. By employing advanced biotechnological and comparative genomic approaches, we elucidated the composition and distribution of regulatory factors across different endophytic fungal genomes associated with B. striata. This research not only advances our understanding of the symbiotic relationship between B. striata and its endophytic fungi but also provides a foundational blueprint for the sustainable exploitation and enhancement of militarine production.

A mass spectrometry-based strategy for investigating volatile molecular interactions in microbial consortia: unveiling a Fusarium-specific induction of an antifungal compound

Co-cultivation of microorganisms has emerged as a promising methodology for deciphering the intricate molecular interactions between species. This approach facilitates the replication of natural niches of ecological or clinical relevance where microbes consistently interact. In this context, increasing attention has been addressed toward elucidating the molecular crosstalk within fungal co-cultures. However, a major challenge in this area of research is determining the fungal origin of metabolites induced in co-cultivation systems. Molecules elicited in co-cultures may not be detectable in the individual cultures, making it challenging to establish which microorganism is responsible for their induction. For agar-diffused metabolites, imaging mass spectrometry can help overcome this obstacle by localizing the induced molecules during fungal confrontations. For volatile metabolites, however, this remains an open problem. To address this issue, in this study, a three-head-to-head co-culture strategy was developed, specifically focusing on the exploration of volatile interactions between fungi via headspace solid-phase microextraction combined with gas chromatography mass spectrometry. This methodology was applied to study the volatile molecular interactions of three fungal species: Fusarium culmorum, Aspergillus amstelodami, and Cladosporium cladosporioides. The adopted strategy revealed a Fusarium-specific induction of three volatile molecules: γ-terpinene and two unidentified sesquiterpene compounds. Interestingly, γ-terpinene showed antifungal activity in a bioassay against the other two fungal species: Aspergillus amstelodami and Cladosporium cladosporioides. The proposed methodology could help to investigate volatile molecular interactions and highlight metabolite induction specific to a particular fungus involved in in vitro fungal confrontations. This is relevant for a better understanding of the complex biosynthetic responses of fungi in consortia and for identifying volatile molecules with antifungal activity.

Unveiling the Genomic Features and Biocontrol Potential of Trichoderma hamatum Against Root Rot Pathogens

Fusarium species are among the most significant pathogens causing root rot in Panax notoginseng. In this study, a strain of Trichoderma hamatum was isolated from the rhizosphere soil of P. notoginseng and subjected to whole-genome sequencing. Plate confrontation experiments were conducted to investigate the antagonistic effects of T. hamatum against Fusarium oxysporum, Fusarium solani, and Fusarium acutatum, the primary Fusarium species causing root rot. Whole-genome sequencing revealed 10,774 predicted genes in T. hamatum, of which 454 were associated with carbohydrate-active enzymes (CAZymes) involved in fungal cell wall degradation. Additionally, 11 biosynthetic gene clusters (BGCs) associated with antimicrobial production were identified, highlighting the biocontrol potential of T. hamatum. In plate confrontation experiments, T. hamatum showed substantial inhibition rates of 68.07%, 70.63%, and 66.12% against F. oxysporum, F. solani, and F. acutatum, respectively. Scanning electron microscopy suggested the hyperparasitism of T. hamatum against F. solani, which was characterized by spore production that adhered to the pathogen, thereby inhibiting its growth. These findings provide a theoretical foundation to enhance understanding of the biological control mechanisms of T. hamatum, supporting its potential applications in sustainable agriculture.

Navigating Climate Change: Exploring the Dynamics Between Plant-Soil Microbiomes and Their Impact on Plant Growth and Productivity

Understanding the intricate interplay between plant and soil microbiomes and their effects on plant growth and productivity is vital in a rapidly changing climate. This review explores the interconnected impacts of climate change on plant-soil microbiomes and their profound effects on agricultural productivity. The ongoing rise in global temperatures, shifting precipitation patterns and extreme weather events significantly affect the composition and function of microbial communities in the rhizosphere. Changes in microbial diversity and activity due to rising temperatures impact nutrient cycling, microbial enzyme synthesis, soil health and pest and disease management. These changes also influence the dynamics of soil microbe communities and their capability to promote plant health. As the climate changes, plants' adaptive capacity and microbial partners become increasingly crucial for sustaining agriculture. Mitigating the adverse effects of climate change on plant growth and agricultural productivity requires a comprehensive understanding of the interconnected mechanisms driving these processes. It highlights various strategies for mitigating and adapting to environmental challenges, including soil management, stress-tolerant crops, cover cropping, sustainable land and water management, crop rotation, organic amendments and the development of climate-resilient crop varieties. It emphasises the need for further exploration of plant-soil microbiomes within the broader context of climate change. Promising mitigation strategies, including precision agriculture and targeted microbiome modifications, offer valuable pathways for future research and practical implementation of global food security and climate change.

Untrimmed ITS2 metabarcode sequences cause artificially reduced abundances of specific fungal taxa

Advances in DNA metabarcoding have greatly expanded our knowledge of microbial communities in recent years. Pipelines and parameters have been tested extensively for bacterial metabarcoding using the 16S rRNA gene and best practices are largely established. For fungal metabarcoding using the internal transcribed spacer (ITS) gene, however, only a few studies have considered how such pipelines and parameters can affect community prediction. Here, we report a novel bias uncovered during ITS region 2 (ITS2) sequencing of Trichoderma-infected ant fungus gardens and confirmed this bias using mock communities. Abnormally low forward read quality caused Trichoderma ITS2 reads to be computationally filtered before and during read pair merging, thus almost entirely eliminating Trichoderma amplicon sequence variants from the resulting fungal community profiles. Sliding window quality trimming before filtering allowed most of these reads to pass filtering and merge successfully, producing community profiles that now correlated with visual signs of Trichoderma infection and matched the composition of the mock communities. Applying such sliding window trimming to a previously generated environmental ITS2 data set increased the detected fungal diversity and again overcame read quality biases against Trichoderma to detect it in nearly every sample instead and often at high relative abundances. This analysis additionally identified a similar, but distinct, bias against a second fungal genus Meyerozyma. The prevalence of such quality biases against other fungal ITS sequences is unknown but may be widespread. We, therefore, advocate for the routine use of sliding window quality trimming as a best practice in ITS2 metabarcoding analysis.

IMPORTANCE

Metabarcode sequencing produces DNA abundance profiles that are presumed to reflect the actual microbial composition of their corresponding input samples. However, this assumption is not always tested, and taxon-specific biases are often not apparent, especially for low-abundance taxa in complex communities. Here, we identified internal transcribed spacer region 2 (ITS2) read quality aberrations that caused dramatic reductions in the relative abundances of specific taxa in multiple data sets characterizing ant fungus gardens. Such taxon-specific biases in read quality may be widespread in other environments and for other fungal taxa, thereby causing incorrect descriptions of these mycobiomes.

Fungi on the cuticle surface increase the resistance of Aedes albopictus to deltamethrin

Aedes albopictus (Ae. albopictus) is widely distributed and can transmit many infectious diseases, and insecticide-based interventions play an important role in vector control. However, increased insecticide resistance has become a severe public health problem, and the clarification of its detailed mechanism is a matter of urgence. This study found that target-site resistance and metabolic resistance could not fully explain insecticide resistance in field Ae. albopictus, and there were likely other resistance mechanisms involved. The 16S and internal transcribed spacer sequencing revealed significant differences in the species compositions of the cuticle surface symbiotic bacteria and fungi between deltamethrin (DM)-resistant (DR) and DM-susceptible (DS) Ae. albopictus. Additionally, the abundances of Serratia spp. and Candida spp. significantly increased after DM treatment. Furthermore, 2 fungi (Rhodotorula mucilaginosa and Candida melibiosica) and 3 bacteria (Serratia marcescens, Klebsiella aerogenes, and Serratia sp.) isolated from DR Ae. albopictus can use DM as their sole carbon source. After reinoculation onto the cuticle surface of DS Ae. albopictus, R. mucilaginosa and C. melibiosica significantly enhanced the DM resistance of Ae. albopictus. Moreover, transcriptome sequencing of the surviving Ae. albopictus after DM exposure revealed that the gene expression of cytochrome P450 enzymes and glutathione-S-transferases increased, suggesting that besides the direct degradation, the candidate degrading microbes could also cause insecticide resistance via indirect enhancement of mosquito gene expression. In conclusion, we demonstrated that the cuticle surface symbiotic microbes were involved in the development of insecticide resistance in Ae. albopictus, providing novel and supplementary insights into insecticide resistance mechanisms.

The intestinal fungus Aspergillus tubingensis promotes polycystic ovary syndrome through a secondary metabolite

Polycystic ovary syndrome (PCOS) affects 6%-10% of women of reproductive age and is known to be associated with disruptions in the gut bacteria. However, the role of the gut mycobiota in PCOS pathology remains unclear. Using culture-dependent and internal transcribed spacer 2 (ITS2)-sequencing methods, we discovered an enrichment of the gut-colonizable fungus Aspergillus tubingensis in 226 individuals, with or without PCOS, from 3 different geographical areas within China. Colonization of mice with A. tubingensis led to a PCOS-like phenotype due to inhibition of Aryl hydrocarbon receptor (AhR) signaling and reduced interleukin (IL)-22 secretion in intestinal group 3 innate lymphoid cells (ILC3s). By developing a strain-diversity-based-activity metabolite screening workflow, we identified secondary metabolite AT-C1 as an endogenous AhR antagonist and a key mediator of PCOS. Our findings demonstrate that an intestinal fungus and its secondary metabolite play a critical role in PCOS pathogenesis, offering a therapeutic strategy for improving the management of the disease.

Fungi in the Gut Microbiota: Interactions, Homeostasis, and Host Physiology

The mammalian gastrointestinal tract is a stage for dynamic inter-kingdom interactions among bacteria, fungi, viruses, and protozoa, which collectively shape the gut micro-ecology and influence host physiology. Despite being a modest fraction, the fungal community, also referred to as mycobiota, represents a critical component of the gut microbiota. Emerging evidence suggests that fungi act as early colonizers of the intestine, exerting a lasting influence on gut development. Meanwhile, the composition of the mycobiota is influenced by multiple factors, with diet, nutrition, drug use (e.g., antimicrobials), and physical condition standing as primary drivers. During its establishment, the mycobiota forms both antagonistic and synergistic relationships with bacterial communities within the host. For instance, intestinal fungi can inhibit bacterial colonization by producing alcohol, while certain bacterial pathogens exploit fungal iron carriers to enhance their growth. However, the regulatory mechanisms governing these complex interactions remain poorly understood. In this review, we first introduce the methodologies for studying the microbiota, then address the significance of the mycobiota in the mammalian intestine, especially during weaning when all 'primary drivers' change, and, finally, discuss interactions between fungi and bacteria under various influencing factors. Our review aims to shed light on the complex inter-kingdom dynamics between fungi and bacteria in gut homeostasis and provide insights into how they can be better understood and managed to improve host health and disease outcomes.

Insights into gut fungi in pigs: A comprehensive review

Fungi in the gut microbiota of mammals play a crucial role in host physiological regulation, including intestinal homeostasis and host immune regulation. However, our understanding of gut fungi in mammals remains limited, especially in economically valuable animals, such as pigs. Therefore, this review first describes the classification and characterisation of fungi, provides insights into the methods used to study gut fungi, and summarises the recent progress on pig gut fungi. Additionally, it discusses the challenges in the study of pig gut fungi and highlights potential perspectives. The aim of this review is to serve as a valuable reference for advancing our knowledge of gut fungi in animals.

Assembly and network of Rhei Radix et Rhizoma surface microbiome shaped by processing methods and sampling locations

Objective

Rhei Radix et Rhizoma has five types of products, namely, raw rhubarb (RR), wine rhubarb (WR), vinegar rhubarb (VR), cooked rhubarb (CR), and rhubarb charcoal (RC). However, Rhei Radix et Rhizoma is easily contaminated with fungi and mycotoxins if not harvested or processed properly. Here, we intend to analyze how microbiome assemblies and co-occurrence patterns are influenced by sampling locations and processing methods.

Methods

High-throughput sequencing and internal transcribed spacer 2 (ITS2) were carried out to study the diversities (α- and β-diversity), composition (dominant taxa and potential biomarkers), and network complexitity of surface fungi on RR, WR, VR, CR, and RC collected from Gansu and Sichuan provinces, China.

Results

The phyla Ascomycota and Basidiomycota; the genera Kazachstania, Malassezia, and Asterotremella; and the species Kazachstania exigua, Asterotremella pseudolonga, and Malassezia restricta were the dominant fungi and exhibited differences in the two provinces and the five processed products. The α-diversity and network complexity were strongly dependent on processing methods. Chao 1, the Shannon index, and network complexity and connectivity were highest in the CR group. The α-diversity and network complexity were influenced by sampling locations. Chao 1 and network complexity and connectivity were highest in the Gansu Province.

Conclusion

The assembly and network of the surface microbiome on Rhei Radix et Rhizoma were shaped by processing methods and sampling locations. This paper offers a comprehensive understanding of microorganisms, which can provide early warning for potential mycotoxins and ensure the safety of drugs and consumers.

Airborne DNA: State of the art - Established methods and missing pieces in the molecular genetic detection of airborne microorganisms, viruses and plant particles

Bioaerosol is composed of different particles, originating from organisms, or their fragments with different origin, shape, and size. Sampling, analysing, identification and describing this airborne diversity has been carried out for over 100 years, and more recently the use of molecular genetic tools has been implemented. However, up to now there are no established protocols or standards for detecting airborne diversity of bacteria, fungi, viruses, pollen, and plant particles. In this review we evaluated commonalities of methods used in molecular genetic based studies in the last 23 years, to give an overview of applicable methods as well as knowledge gaps in diversity assessment. Various sampling techniques show different levels of effectiveness in detecting airborne particles based on their DNA. The storage and processing of samples, as well as DNA processing, influences the outcome of sampling campaigns. Moreover, the decisions on barcode selection, method of analysis, reference database as well as negative and positive controls may severely impact the results obtained. To date, the chain of decisions, methodological biases and error propagation have hindered DNA based molecular sequencing from offering a holistic picture of the airborne biodiversity. Reviewing the available studies, revealed a great diversity in used methodology and many publications didn't state all used methods in detail, making comparisons with other studies difficult or impossible. To overcome these limitations and ensure genuine comparability across studies, it is crucial to standardize protocols. Publications need to include all necessary information to enable comparison among different studies and to evaluate how methodological choices can impacts the results. Besides standardization, implementing of automatic tools and combining of different analytical techniques, such as real-time evaluation combined with sampling and molecular genetic analysis, could assist in achieving the goal of accurately assessing the actual airborne biodiversity.

Gut Mycobiota of Three Rhinopithecus Species Provide New Insights Into the Association Between Diet and Environment

Gut mycobiota are part of the gut microbiome, typically derived from the host diet and living environment. In this study, we examined the gut mycobiota of three snub-nosed monkeys: Rhinopithecus roxellana, R. bieti, and R. strykeri using next-generation amplicon sequencing targeting the fungal internal transcribed spacer. The alpha diversity indexes of gut mycobiota in R. bieti were significantly higher than R. roxellana and R. strykeri, the beta diversity indicated that R. roxellana and R. bieti had more similar feeding habits. Core mycobiota demonstrated commonalities among the three species and potentially associated with feeding habits. Mycobiota displaying significant differences exhibited the respective characteristics of the host, likely associated with the hosts' living environment. Among them, animal and plant pathogenic fungi and lichen parasites are potential threats to the survival of snub-nosed monkeys for their pathogenicity to both monkeys and their food plants. Functionally, fungal trophic modes and functional guilds revealed a strong association between gut mycobiota and host diet. We found a higher abundance and more significant correlations with lichen parasitic fungi in R. strykeri than the other two species, indicating potential threats to their foods. Accordingly, this study revealed the basic structures of gut mycobiota of three wild Rhinopithecus species and highlighted the associations between gut mycobiota and their feeding habits and living environments. Furthermore, due to the close connection between fungi and the environment, animals could ingest fungi from their diet; thus, we speculate that gut mycobiota may serve a role in environmental monitoring for wildlife.

Methodology comparison of environmental sediment fungal community analysis

Fungi play important roles in ecosystems. Analyzing fungal communities in environments has long been a challenge due to the large difference in compositions retrieved using different methods or sequencing regions, obscuring the true abundance and species information. Our study aimed to compare and determine more accurate approach for evaluating fungal populations in river sediment. To achieve this, different primer sets in the internal transcribed spacer (ITS) (ITS5/ITS1R, ITS1F/ITS2), 18S rRNA gene (0817F/1196R) for High-throughput sequencing (HTS), metagenomic shotgun sequencing (MS) directly from environmental samples, and HTS using ITS primers for the fungal samples collected from plate cultivation were used to characterize the fungal communities. We calculated diversity index and used FungalTraits to analyze methods preferences for fungal species. The study revealed that when analyzing the fungal species directly from environmental samples, amplification and sequencing of ITS region demonstrated more accuracy than MS and 18S rRNA gene sequencing methods, but displayed significant primer preference. Over 30 % fungal species from HTS after plate cultivation were not present in HTS from the environmental samples. NMDS analysis demonstrated significant disparities in species diversity among different methods, suggesting potential complementarity between them. Over 85% species identified by HTS using ITS primers belonged to filamentous fungi, while the MS mostly identified yeast (62%). Therefore, to get more accurate fungal community information in sediment, multiple methods were recommended by using cultivation, molecular biological methods dependent on PCR techniques like ITS1F/ITS2 primer for HTS and PCR independent method such as metagenomic shotgun sequencing techniques.

Evaluation of DNA Extraction Methods for Microbial Community Profiling in Deadwood Decomposition

As technologies advance alongside metabarcoding and metagenomic resources, particularly for larger fungal genomes, DNA extraction methods must be optimized to meet higher thresholds, especially from complex environmental substrates. This study focused on extracting fungal genomic compounds from woody substrates, a challenge due to the embedment of endophytic and saprotrophic fungi within wood cells, the physical recalcitrance of wood, the adsorption of nucleic acids to wood polymers, and the release of downstream inhibitors. Hypothesizing that cetyltrimethylammonium bromide would be the best option, we compared prominent methods by extracting and sequencing microbial DNA from sound and decayed birch (Betula papyrifera) and pine (Pinus resinosa). DNA quantities varied significantly depending on extraction methods and decay stage. The quality of DNA, in terms of purity and integrity, significantly impacted whether the samples could be amplified and sequenced. However, amplicon sequencing of bacterial and fungal communities revealed no significant extraction bias. This, along with the sequencing effectiveness and cost/time efficiency, indicates that Qiagen is the gold standard for woody substrates. This study increases confidence in published amplicon data sets regardless of the extraction methods, provides a cost-benefit table for making protocol decisions, and offers guidance on fungal DNA extractions from complex organic substrates (sound and decayed wood) that would best suit future metagenomic efforts.

Environmental concentrations of the fungicide tebuconazole alter microbial biodiversity and trigger biofilm-released transformation products

Freshwater microbial communities are integral components of riverine biodiversity. The ecological effects of toxic chemical pollutants, such as fungicides (e.g., tebuconazole), on microbial abundance and diversity are needed for risk assessment and regulation. The emergence of RNA metabarcoding approaches allow us to describe at unprecedented resolution the microbial diversity of the active part of a microbial community. Our study assesses the ecotoxicological impact of chronic and acute tebuconazole exposures on fungal, bacterial, and algal biomass and biodiversity of aquatic fungi and bacteria in stream biofilms using an RNA metabarcoding approach. In addition, the study uses HPLC-MS to evaluate the capability of biofilms to metabolize tebuconazole. Natural biofilm communities from a Swedish stream were exposed chronically (24 days) and acutely (96 h) to environmental concentrations of tebuconazole (10 and 100 μg/L) in microcosms conditions. The diversity and community structure of fungi and bacteria was assessed by ITS2 and 16S cDNA amplicon-sequencing, respectively. Biofilms chronically exposed to tebuconazole produced and released unidentified transformation products into the water column, suggesting a biotransformation capability following 24 days of uninterrupted exposure. The fungal biomass markedly decreased by a biomass loss of 40% when chronically exposed to 10 μg/L, and 60% when chronically exposed to 100 μg/L. Bacterial and algal biomass remained comparable with the controls in all tebuconazole treatments. Fungal and bacterial alpha diversity metrics were not significantly impacted, although a decreasing trend in fungal richness was observed with the treatments. However, beta diversity was significantly impacted in both fungal and bacterial compartments. Chronic exposures resulted in a shift in community composition, where taxa potentially more tolerant to tebuconazole (i.e. Lecanoromycetes) replaced more sensitive taxa (i.e. Malasseziomycetes). This study indicates that tebuconazole at environmental concentrations might pose a risk to freshwater systems, mainly due to its high toxicity to fungi.

Species diversity, taxonomic classification and ecological habits of polypore fungi in China

Polypore fungi are an important part of forest ecosystems. In the last decade, the taxonomic status and species number of polypore fungi have changed greatly, and many new taxa have been discovered. China is one of the countries with the most abundant and diverse polypore fungi in the world, and a total of 1,214 polypore fungal species were reported here. This study lists the polypore fungi with their diversity, taxonomic status, habitats, geographical distributions, and molecular data. All the polypore fungi in China belong to the phylum Basidiomycota, subphylum Agaricomycotina, and class Agaricomycetes, including 11 orders, 55 families, and 266 genera. The orders Polyporales and Hymenochaetales are dominant, and the families Polyporaceae and Hymenochaetaceae are dominant. The overall distribution trend of polypore fungi in China shows that more species are distributed in the south and fewer are distributed in the north. In addition, different nutritional modes of polypore fungi have different preferences for host species, with white-rot fungi preferring angiosperm trees and brown-rot fungi preferring gymnosperm trees.

Seasonal shifts and land-use impact: unveiling the gut microbiomes of bank voles (Myodes glareolus) and common voles (Microtus arvalis)

Gut microbial diversity influences the health and vitality of the host, yet it is itself affected by internal and external factors, including land-use. The impact of land-use practices on wild rodents' gut microbiomes remains understudied, despite their abundance and potential as reservoirs for zoonotic pathogens. We examined the bacterial and fungal gut microbiomes of bank voles (Myodes glareolus) and common voles (Microtus arvalis) across grassland and forest habitats with varying land-use intensities and types. We collected rodents seasonally and used 16S rRNA and ITS amplicon sequencing for microbe identification. We found significant differences in alpha and beta diversities between the species, with M. arvalis exhibiting higher diversity. Seasonality emerged as a prominent factor influencing microbial diversity, with significant variations between sampling months. While land-use affects the gut microbiome, its impact is subordinate to seasonal variations. Differential abundance analysis underscores the dynamic nature of microbial composition, with seasonal changes playing a predominant role. Overall, our findings highlight the significant influence of seasonality on gut microbiome diversity and composition in wild rodents, reflecting dietary shifts associated with seasonal changes. Understanding the interplay between environmental factors and microbial communities in wild rodents enahnces our knowledge of ecosystem health and resilience, warranting further investigation.

Comparison of commonly used software pipelines for analyzing fungal metabarcoding data

BACKGROUND

Metabarcoding targeting the internal transcribed spacer (ITS) region is commonly used to characterize fungal communities of various environments. Given their size and complexity, raw ITS sequences are necessarily processed and quality-filtered with bioinformatic pipelines. However, such pipelines are not yet standardized, especially for fungal communities, and those available may produce contrasting results. While some pipelines cluster sequences based on a specified percentage of base pair similarity into operational taxonomic units (OTUs), others utilize denoising techniques to infer amplicon sequencing variants (ASVs). While ASVs are now considered a more accurate representation of taxonomic diversity for prokaryote communities based on 16S rRNA amplicon sequencing, the applicability of this method for fungal ITS sequences is still debated.

RESULTS

Here we compared the performance of two commonly used pipelines DADA2 (inferring ASVs) and mothur (clustering OTUs) on fungal metabarcoding sequences originating from two different environmental sample types (fresh bovine feces and pasture soil). At a 99% OTU similarity threshold, mothur consistently identified a higher fungal richness compared to DADA2. In addition, mothur generated homogenous relative abundances across multiple technical replicates (n = 18), while DADA2 results for the same replicates were highly heterogeneous.

CONCLUSIONS

Our study highlights a potential pipeline-associated bias in fungal metabarcoding data analysis of environmental samples. Based on the homogeneity of relative abundances across replicates and the capacity to detect OTUs/ASVs, we suggest using OTU clustering with a similarity of 97% as the most appropriate option for processing fungal metabarcoding data.

Long-term garlic‒maize rotation maintains the stable garlic rhizosphere microecology

BACKGROUND

Crop rotation is a sophisticated agricultural practice that can modify the demographic structure and abundance of microorganisms in the soil, stimulate the growth and proliferation of beneficial microorganisms, and inhibit the development of harmful microorganisms. The stability of the rhizosphere microbiome is crucial for maintaining both soil ecosystem vitality and crop prosperity. However, the effects of extended garlic‒maize rotation on the physicochemical characteristics of garlic rhizosphere soil and the stability of its microbiome remain unclear. To investigate this phenomenon, soil samples from the garlic rhizosphere were collected across four different lengths of rotation in a garlic-maize rotation.

RESULTS

There were notable positive associations between the total nitrogen and total phosphorus contents in the soil and the duration of rotation. Prolonged rotation could increase the maintenance of microbiome α diversity. The number of years of rotation and the soil organic carbon (SOC) content emerged as principal determinants impacting the evolution of the bacterial community structure, with the SOC content playing a pivotal role in sculpting the species diversity within the garlic rhizosphere bacterial community. Additionally, SOC remains predominant in shaping the root-associated bacterial community's β-nearest taxon index. However, these factors do not have a notable effect on the fungal community inhabiting the garlic rhizosphere. In comparison with monoculture, rotation can amplify the interconnectivity and intricacy of microbial ecological networks. Long-term rotation can further maintain the stability of both microbial ecological networks and interactions between bacterial and fungal communities. It can enlist a plethora of beneficial Bacillus species microorganisms within the garlic rhizosphere to form a biological barricade that aids in safeguarding garlic against encroachment by the pathogenic fungus Fusarium oxysporum, consequently diminishing disease incidence. This study provides a theoretical foundation for the sustainable development of garlic through long-term crop rotation with maize.

CONCLUSIONS

Our research results indicate that long-term garlic‒maize rotation maintains stable garlic rhizosphere microecology. Our study provides compelling evidence for the role of long-term crop rotation in maintaining microbiota and community stability, emphasizing the importance of cultivating specific beneficial microorganisms to enhance rotation strategies for garlic farming, thereby promoting sustainability in agriculture.

Differential contribution of microbial and plant-derived organic matter to soil organic carbon sequestration over two decades of natural revegetation and cropping

Both natural revegetation and cropping have great impact on long-term soil carbon (C) sequestration, yet the differences in their underlying mechanisms remain unclear. In this study, we investigated trends in soil organic C (SOC) accumulation during natural revegetation (VR) and cropping processes over 24 years, and explored the contributions of microbial necromass and plant-derived C to SOC formation and their primary controls. Over the course of 24 years of land use/cover change (LUCC) from 1995, SOC content exhibited a more substantial increase in VR (0.31 g kg-1 a-1) than in cropland (0.14 g kg-1 a-1) during Stage II (>10 y after LUCC), and recalcitrant organic carbon explained more of the SOC variation than easily oxidizable carbon. The higher SOC content in VR was attributed to a greater contribution of plant-derived C (14-28 %) than that in cropland (3-11 %) to SOC and a consistently lower ratio of cinnamyl (C)- to vanillyl (V)-type phenols in VR across all the assessed years. Although there were higher proportion of microbial necromass of SOC (41-84 %) in cropland than in VR, the differences were not significant. The dominant bacterial phylum of Chloroflexi and soil nitrogen content were the primary biotic and abiotic factors regulating microbial-derived and plant-derived C in both cropland and VR. However, soil phosphorus content was the main factor in cropland, while climatic factors such as mean annual precipitation were more important in VR. These results provided evidence that long-term natural revegetation enhanced SOC sequestration by greater contribution of plant-derived C to SOC formation compared to cropping. These findings underscore the synergistic contribution of vegetation and microorganisms to long-term SOC sequestration, offering insights into the different mechanisms of carbon formation during VR and cropping processes, and providing support for optimizing land management to achieve global carbon neutrality goals.

New insights into the roles of fungi and bacteria in the development of medicinal plant

BACKGROUND

The interaction between microorganisms and medicinal plants is a popular topic. Previous studies consistently reported that microorganisms were mainly considered pathogens or contaminants. However, with the development of microbial detection technology, it has been demonstrated that fungi and bacteria affect beneficially the medicinal plant production chain.

AIM OF REVIEW

Microorganisms greatly affect medicinal plants, with microbial biosynthesis a high regarded topic in medicinal plant-microbial interactions. However, it lacks a systematic review discussing this relationship. Current microbial detection technologies also have certain advantages and disadvantages, it is essential to compare the characteristics of various technologies.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review first illustrates the role of fungi and bacteria in various medicinal plant production procedures, discusses the development of microbial detection and identification technologies in recent years, and concludes with microbial biosynthesis of natural products. The relationship between fungi, bacteria, and medicinal plants is discussed comprehensively. We also propose a future research model and direction for further studies.

Seasonal Variations of Sediment Fungal Community of a Shallow Lake in North China

Fungi play important roles in the process of material cycling and energy transfers in aquatic ecosystems. Yet, little is known about the fungal community in lake sediment. In this study, sediment samples from five habitat types in Baiyangdian Lake (BYD Lake) were collected across three seasons. High-throughput sequencing techniques were used to determine the compositions of fungal communities. Fungi are highly diverse in the sediment of BYD Lake, although some important fungi have not been accurately identified. The fungal diversity was highest in winter and lowest in summer, while there was no significant difference in species richness among sampling sites. The compositions of fungal community differed among seasons and habitats. Physicochemical properties of sediments were measured and the influence of the environmental factors on fungal communities were analyzed. Temperature, P, N, and heavy metals explained 48.98% of the variations of fungal communities across three seasons. Human activities have affected the species and biomass of fungi to some extent. Temperature is the most influential factor and negatively correlated to fungal diversity. Nutrients in different forms have different effects on shaping the fungal community. The effect of heavy metals is relatively low.

Application of microorganisms in Panax ginseng: cultivation of plants, and biotransformation and bioactivity of key component ginsenosides

Panax ginseng is a precious Chinese medicinal plant with a long growth cycle and high medicinal value. Therefore, it is of great significance to explore effective ways to increase its yield and main active substance content to reduce the cost of ginseng, which is widely used in food and clinical applications. Here, we review the key roles of microorganisms in the biological control of ginseng diseases, enhancement of ginseng yield, biotransformation of ginsenosides, and augmentation of ginsenoside bioactivity. The application of microorganisms in P. ginseng faces multiple challenges, including the need for further exploration of efficient microbial strain resources used in the cultivation of ginseng and biotransformation of ginsenosides, lack of microbial application in large-scale field cultivation of ginseng, and unclear mechanism of microbial transformation of ginsenosides. This review provides a deeper understanding of the applications of microorganisms in P. ginseng.

Detection Methods for Pine Wilt Disease: A Comprehensive Review

Pine wilt disease (PWD), caused by the nematode Bursaphelenchus xylophilus, is a highly destructive forest disease that necessitates rapid and precise identification for effective management and control. This study evaluates various detection methods for PWD, including morphological diagnosis, molecular techniques, and remote sensing. While traditional methods are economical, they are limited by their inability to detect subtle or early changes and require considerable time and expertise. To overcome these challenges, this study emphasizes advanced molecular approaches such as real-time polymerase chain reaction (RT-PCR), droplet digital PCR (ddPCR), and loop-mediated isothermal amplification (LAMP) coupled with CRISPR/Cas12a, which offer fast and accurate pathogen detection. Additionally, DNA barcoding and microarrays facilitate species identification, and proteomics can provide insights into infection-specific protein signatures. The study also highlights remote sensing technologies, including satellite imagery and unmanned aerial vehicle (UAV)-based hyperspectral analysis, for their capability to monitor PWD by detecting asymptomatic diseases through changes in the spectral signatures of trees. Future research should focus on combining traditional and innovative techniques, refining visual inspection processes, developing rapid and portable diagnostic tools for field application, and exploring the potential of volatile organic compound analysis and machine learning algorithms for early disease detection. Integrating diverse methods and adopting innovative technologies are crucial to effectively control this lethal forest disease.

Optimization of a DNA extraction protocol for improving bacterial and fungal classification based on Nanopore sequencing

Ribosomal RNA gene amplicon sequencing is commonly used to evaluate microbiome profiles in health and disease and document the impact of interventional treatments. Nanopore sequencing is attractive since it can provide greater classification at the species level. However, optimized protocols to target marker genes for bacterial and fungal profiling are needed. To achieve an increased taxonomic resolution, we developed extraction and full-length amplicon PCR-based approaches using Nanopore sequencing. Three lysis conditions were applied to a mock microbial community, including known bacterial and fungal species: ZymoBIOMICS lysis buffer (ML) alone, incorporating bead-beating (MLB) or bead-beating plus MetaPolyzyme enzymatic treatment (MLBE). In profiling of bacteria in comparison to reference data, MLB had more statistically different bacterial phyla and genera than the other two conditions. In fungal profiling, MLB had a significant increase of Ascomycota and a decline of Basidiomycota, subsequently failing to detect Malassezia and Cryptococcus. Also, a principal coordinates analysis plot by the Bray-Curtis metric showed a significant difference among groups for bacterial (P=0.033) and fungal (P=0.012) profiles, highlighting the importance of understanding the biases present in pretreatment. Overall, microbial profiling and diversity analysis revealed that ML and MLBE are more similar than MLB for both bacteria and fungi; therefore, using this specific pipeline, bead-beating is not recommended for whole gene amplicon sequencing. However, ML alone was suggested as an optimal approach considering DNA yield, taxonomic classification, reagent cost and hands-on time. This could be an initial proof-of-concept study for simultaneous human bacterial and fungal microbiome studies.

The rootstock genotype shapes the diversity of pecan (Carya illinoinensis) rhizosphere microbial community

Pecans (Carya illinoinensis), one of the most valuable native North American nut crops, are commonly propagated through grafting to preserve the desired characteristics from parent trees. Since successful cultivation of pecan trees relies on the interplay among scion varieties, rootstocks, and soil conditions, this study investigated the microbial change to communities in the soils and roots of southern (87MX5-1.7) and northern (Peruque) rootstocks in a rootstock test orchard. Both grafted with the 'Pawnee' scion cultivar. Bacterial 16S ribosomal RNA and fungal ITS were amplified from both roots and rhizosphere soils of the two 10-year-grafted trees, then sequenced and annotated into trophic and nutrient-related groups to characterize the rhizosphere microbiota. The Peruque roots had a higher relative abundance of saprotroph fungi, while 87MX5-1.7 exhibited higher levels of symbiotroph fungi and nitrogen fixation-related bacteria. Among them, the presence of symbiotroph fungi, particularly ectomycorrhizal fungi, notably differed between these two rootstocks, with a significantly higher presence observed in the root of 87MX5-1.7 compared to Peruque. This variation likely leads to divergent pathways of nutrient translocation: Peruque was in favor of multiple fungi (Russula and Inocybe) to gain nutrition, while 87MX5-1.7 preferred a specific domain of fungi (Tuber) and nitrogen fixation-related bacteria (Bradyrhizobia) to form beneficial symbiosis. Moreover, the presence of pathogens suggested a potential risk of Fusarium patch and snow molds in 87MX5-1.7, while canker and black foot disease pose threats in Peruque. The findings of this study suggest that rootstocks from different origins shape rhizosphere microbes differently, potentially affecting nutrient uptake and nut yield. Exploring rootstock-microbe combinations could provide insights into optimizing scion growth and ultimately increasing nut yield. By understanding how different rootstock-microbe interactions influence pecan tree development, growers can strategically select combinations that promote beneficial symbiotic relationships, enhancing nutrient uptake, disease resistance, and overall tree vigor.

Linking soil nutrients, microbial community composition, and enzyme activities to saponin content of Paris polyphylla after addition of biochar and organic fertiliser

The application of organic fertilisers and biochar has become widespread in agroforestry ecosystems to enhance the yield and quality of crops and medicinal plants. However, their specific impact on both the yield and quality of Paris polyphylla (P. polyphylla), along with the underlying mechanisms, remains unclear. In this study, we investigated the distinct effects of organic fertiliser (at concentrations of 5% and 10%) and biochar application (at levels of 2% and 4%) on P. polyphylla saponin content. This content is intricately regulated by available soil nutrients, enzyme activities, and microbial community compositions and activities. Our results clearly demonstrated a significant increase in the saponin content, including total saponin, polyphyllin I (PPI), polyphyllin II (PPII), polyphyllin VI (PPVI), and polyphyllin VII (PPVII), in P. polyphylla following the application of both biochar and organic fertiliser. Moreover, in comparison to the control group, the addition of biochar and organic fertiliser led to a considerable rise in the activity of glycosyltransferase enzyme (GTS) and cycloartenol synthase (CAS) in P. polyphylla. Additionally, it increased soil available potassium (AK) and soil organic matter (SOM) concentration, along with the activity of urease, acid phosphatase, and catalase, although biochar amendment resulted in a decrease in nitrate nitrogen (NO3--N) concentration. Crucially, our findings revealed a positive correlation between total saponin content and the activity of CAS in P. polyphylla, soil AK, SOM concentration, and the activities of urease, acid phosphatase, and catalase. Conversely, there was a negative correlation with NO3--N content. Furthermore, the application of organic fertiliser and biochar significantly influenced microbial community structures and specific microbial taxa. Notably, total saponin content exhibited a positive relationship with the relative abundances of Dehalococcoidia, Saccharomycetes, and Agaricomycetes taxa while showing a negative correlation with the abundance of Verrucomicrobiae. In conclusion, the observed increase in saponin content can be attributed to the modulation of specific microbial taxa in soils, as well as alterations in soil nutrients and enzyme activities resulting from the application of biochar and organic fertiliser. This study identifies a potential mechanism for enhancing saponin content in the artificial cultivation of P. polyphylla.

Soil keystone viruses are regulators of ecosystem multifunctionality

Ecosystem multifunctionality reflects the capacity of ecosystems to simultaneously maintain multiple functions which are essential bases for human sustainable development. Whereas viruses are a major component of the soil microbiome that drive ecosystem functions across biomes, the relationships between soil viral diversity and ecosystem multifunctionality remain under-studied. To address this critical knowledge gap, we employed a combination of amplicon and metagenomic sequencing to assess prokaryotic, fungal and viral diversity, and to link viruses to putative hosts. We described the features of viruses and their potential hosts in 154 soil samples from 29 farmlands and 25 forests distributed across China. Although 4,460 and 5,207 viral populations (vOTUs) were found in the farmlands and forests respectively, the diversity of specific vOTUs rather than overall soil viral diversity was positively correlated with ecosystem multifunctionality in both ecosystem types. Furthermore, the diversity of these keystone vOTUs, despite being 10-100 times lower than prokaryotic or fungal diversity, was a better predictor of ecosystem multifunctionality and more strongly associated with the relative abundances of prokaryotic genes related to soil nutrient cycling. Gemmatimonadota and Actinobacteria dominated the host community of soil keystone viruses in the farmlands and forests respectively, but were either absent or showed a significantly lower relative abundance in that of soil non-keystone viruses. These findings provide novel insights into the regulators of ecosystem multifunctionality and have important implications for the management of ecosystem functioning.

Diversity and Composition of Fungicolous Fungi Residing in Macrofungi from the Qinling Mountains

Sporocarps of macrofungi support other diverse fungal species that are termed fungicolous fungi. However, the external environmental factors that affect the diversity and composition of fungicolous fungal communities remains largely unknown. In this study, the diversities, composition, and trophic modes of fungicolous fungal communities residing in host macrofungi from diverse habitats in the Qinling Mountains were analyzed. Additionally, the number of carbohydrate-active enzymes (CAZymes) encoded by saprophytic, pathogenic, and symbiotic fungi was also quantified and compared. The results revealed that the diversity and composition of fungicolous fungal communities varied with months of collection and the habitats of host fungi, and saprophytic fungi were more abundant on wood than on the ground. Meanwhile, it was also found that saprophytic fungi possessed higher abundances of cell-wall-degrading enzymes than pathogenic or symbiotic fungi. Based on the above findings, it was hypothesized that the greater abundance of saprophytic fungi on wood compared to the ground may be due to their possession of a more diverse array of enzymes capable of degrading wood cell walls, thereby allowing for more efficient nutrient acquisition from decaying wood.

Proposals for consideration at IMC12 to modify provisions related solely to fungi in Chapter F of the International Code of Nomenclature for algae, fungi, and plants

Seven proposals or sets of proposals to modify the provisions of Chapter F of the International Code of Nomenclature for algae, fungi, and plants (ICNafp) have been received. These proposals are formally presented together here. The topics addressed relate to: fungi whose morph-names have the same epithet; the listing of synonyms under entries for protected names in the Code Appendices; the processes of protection and rejection; the use of DNA sequences as nomenclatural types; the use of genomes as nomenclatural types; and the designation of fungi known only from DNA sequences. In addition, a suggestion is included to update the mention of the World Directory of Culture Collections in Article 40.7 Note 4. A Synopsis of the formal proposals will be provided in early July 2024, and the mycological community will be invited to provide a guiding vote on the proposals with a closing date of 2 August 2024. Final decisions on the proposals will be made following debate at the Fungal Nomenclature Session of IMC12 in August 2024.

Gut mycobiome alterations and implications for liver diseases

Chronic liver disease and its complications are a significant global health burden. Changes in fungal communities (mycobiome), an integral component of the gut microbiome, are associated with and contribute to the development of liver disease. Fungal dysbiosis can induce intestinal barrier dysfunction and allow fungal products to translocate to the liver causing progression of disease. This review explores recent progress in understanding the compositional and functional diversity of gut mycobiome signatures across different liver diseases. It delves into causative connections between gut fungi and liver diseases. We emphasize the significance of fungal translocation, with a particular focus on fungal-derived metabolites and immune cells induced by fungi, as key contributors to liver disease. Furthermore, we review the potential impact of the intrahepatic mycobiome on the progression of liver diseases.

Sex-specific phosphorus acquisition strategies and cycling in dioecious Populus euphratica forests along a natural water availability gradient

Soil phosphorus (P) availability affects plant growth and distribution. However, it is still unknown how sex-specific variation in functional traits affects plants' P acquisition and soil P transformation. On wet sites, female poplars had a greater specific root length (SRL), and a higher diversity of arbuscular mycorrhizal fungi (AMF) and phosphate-solubilizing bacteria (PSB). Male poplars living on wet sites increased the abundance of AMF and PSB communities and enhanced moderately labile and highly resistant organic P mineralisation via increased phosphatase activity. In contrast, on the dry site, the abundance and diversity of AMF and PSB communities increased in females, enhancing moderately labile and highly resistant organic P mineralisation via elevating phosphatase activities. Males maintained greater SRL and promoted Ca-P mobilisation via the release of root carboxylic acids and rhizosphere acidification on the dry site. The AMF community diversity followed a similar pattern as that of the PSB community when altering the P availability of different-sex plants. Our results indicated that organic P and Ca-P are the major sources of plant-available P in natural P. euphratica forests. Seasonal shifts and geographic locations affected the share of organic and inorganic P pools, and AMF and PSB diversities, ultimately altering sex-specific P acquisition strategies of plants.

Intercropping enhances maize growth and nutrient uptake by driving the link between rhizosphere metabolites and microbiomes

Intercropping leads to different plant roots directly influencing belowground processes and has gained interest for its promotion of increased crop yields and resource utilization. However, the precise mechanisms through which the interactions between rhizosphere metabolites and the microbiome contribute to plant production remain ambiguous, thus impeding the understanding of the yield-enhancing advantages of intercropping. This study conducted field experiments (initiated in 2013) and pot experiments, coupled with multi-omics analysis, to investigate plant-metabolite-microbiome interactions in the rhizosphere of maize. Field-based data revealed significant differences in metabolite and microbiome profiles between the rhizosphere soils of maize monoculture and intercropping. In particular, intercropping soils exhibited higher microbial diversity and metabolite chemodiversity. The chemodiversity and composition of rhizosphere metabolites were significantly related to the diversity, community composition, and network complexity of soil microbiomes, and this relationship further impacted plant nutrient uptake. Pot-based findings demonstrated that the exogenous application of a metabolic mixture comprising key components enriched by intercropping (soyasapogenol B, 6-hydroxynicotinic acid, lycorine, shikimic acid, and phosphocreatine) significantly enhanced root activity, nutrient content, and biomass of maize in natural soil, but not in sterilized soil. Overall, this study emphasized the significance of rhizosphere metabolite-microbe interactions in enhancing yields in intercropping systems. It can provide new insights into rhizosphere controls within intensive agroecosystems, aiming to enhance crop production and ecosystem services.

Unraveling the habitat preferences, ecological drivers, potential hosts, and auxiliary metabolism of soil giant viruses across China

BACKGROUND

Soil giant viruses are increasingly believed to have profound effects on ecological functioning by infecting diverse eukaryotes. However, their biogeography and ecology remain poorly understood.

RESULTS

In this study, we analyzed 333 soil metagenomes from 5 habitat types (farmland, forest, grassland, Gobi desert, and mine wasteland) across China and identified 533 distinct giant virus phylotypes affiliated with nine families, thereby greatly expanding the diversity of soil giant viruses. Among the nine families, Pithoviridae were the most diverse. The majority of phylotypes exhibited a heterogeneous distribution among habitat types, with a remarkably high proportion of unique phylotypes in mine wasteland. The abundances of phylotypes were negatively correlated with their environmental ranges. A total of 76 phylotypes recovered in this study were detectable in a published global topsoil metagenome dataset. Among climatic, geographical, edaphic, and biotic characteristics, soil eukaryotes were identified as the most important driver of beta-diversity of giant viral communities across habitat types. Moreover, co-occurrence network analysis revealed some pairings between giant viral phylotypes and eukaryotes (protozoa, fungi, and algae). Analysis of 44 medium- to high-quality giant virus genomes recovered from our metagenomes uncovered not only their highly shared functions but also their novel auxiliary metabolic genes related to carbon, sulfur, and phosphorus cycling.

CONCLUSIONS

These findings extend our knowledge of diversity, habitat preferences, ecological drivers, potential hosts, and auxiliary metabolism of soil giant viruses. Video Abstract.