mSystems最新文献

Microbial interactions in cheese rinds influence community structure, food safety, and product quality. But the chemical mechanisms that mediate microbial interactions in cheeses and other fermented foods are generally not known. Here, we investigate how the spoilage mold Aspergillus westerdijkiae chemically inhibits beneficial cheese-rind bacteria using a combination of omics technologies. In cheese-rind community and co-culture experiments, A. westerdijkiae strongly inhibited most cheese-rind community members. In co-culture with Staphylococcus equorum, A. westerdijkiae strongly affected bacterial gene expression, including upregulation of a putative bceAB gene cluster that is associated with resistance to antimicrobial compounds in other bacteria. Mass spectrometry imaging revealed spatially localized production of secondary metabolites, including penicillic acid and ochratoxin B at the fungal-bacterial interface with Brachybacterium alimentarium. Integration of liquid chromatography-tandem mass spectrometry and genome annotations confirmed the presence of additional bioactive metabolites, such as notoamides and circumdatins. Fungal metabolic responses varied by bacterial partner, suggesting species-specific chemical strategies. Notably, penicillic acid levels increased 2.5-fold during interaction with B. alimentarium, and experiments with purified penicillic acid showed inhibition in a dose-dependent manner against this rind bacterium. These findings show that A. westerdijkiae deploys a context-dependent suite of mycotoxins and other metabolites, disrupting microbial community assembly in cheese rinds.IMPORTANCEThis study identifies the chemical mechanisms underlying the negative impacts of Aspergillus westerdijkiae on cheese-rind development, revealing how specialized metabolites like penicillic acid and ochratoxin B influence rind bacterial communities. By integrating biosynthetic gene cluster analyses with mass spectrometry, we demonstrate how chemical communication shapes microbial interactions, with possible implications for food safety and cheese quality. Understanding these interactions is essential for assessing the risks of fungal-driven spoilage and mycotoxin production in cheese-rind maturation. Beyond cheese, these findings contribute to broader microbiome ecology, emphasizing how secondary metabolites mediate microbial competition in natural and fermented food environments.

Optimization of prophylactic vaccine regimens to elicit strong, long-lasting immunity is an urgent need highlighted by the COVID-19 pandemic. Stronger vaccine immunogenicity is frequently reported in individuals living in high-income countries compared to individuals living in low- and middle-income countries. While numerous host genetic and immune factors may influence vaccine responses, geographic restrictions to vaccine effectiveness may also be influenced by the intestinal microbiota, which modulates host immune systems. However, the potential role of the gut microbiota on responses to HIV-1 vaccines has not yet been explored. We analyzed the bacteriome by targeted 16S sequencing and the virome by virus-like particle sequencing of 154 fecal samples collected from healthy individuals in Uganda, Rwanda, and the United States early (week 2) and late (week 26) after vaccination with multivalent adenovirus serotype 26 (Ad26)-vectored mosaic HIV-1 vaccines. Vaccination did not affect the enteric bacteriome or virome regardless of geographic location. However, geography was the major driver of microbiota differences within this cohort. Differences in overall bacterial and viral diversity and in specific microbial taxa, including Bacteroidota and Bacillota, between participants from the United States and East African countries correlated with differential immune responses, including specific antibody titers, antibody functionality, and cellular immune responses to vaccination regimens. These findings support the microbiota as a putative modifier of vaccine immunogenicity.IMPORTANCEOur research examined how gut bacteria might influence vaccine effectiveness in different parts of the world. We studied adults from the United States, Rwanda, and Uganda who received an experimental HIV vaccine. We found that participants from East Africa had more diverse gut bacteria than those from the United States, but their immune responses to the vaccine were weaker. This is the first study to directly show this relationship between higher gut bacterial diversity and reduced vaccine effectiveness in the same group of people. We also identified specific types of bacteria that were linked to either stronger or weaker immune responses. These findings are particularly relevant now as we use vaccines globally to fight diseases like COVID-19, as they suggest that regional differences in gut bacteria Bacteroidota and Bacillota might help explain why vaccines work better in some places than others. This could inform how we design and test future vaccines.

Microbial colonization of plant roots involves strong selective pressures that shape the structure and function of root-associated communities. In particular, the endosphere represents a highly selective environment requiring host entry and in planta persistence. However, strain-specific microbial traits that enable endosphere colonization remain poorly understood. Here, we use a defined, genome-resolved community of 28 Variovorax strains isolated from the roots of Populus deltoides and Populus trichocarpa (poplar trees) to determine which strains partition between rhizosphere and endosphere compartments and to identify the genomic traits associated with endosphere specialization. By combining strain-resolved metagenomic profiling, comparative genomics, and functional assays, we demonstrate that dominant endosphere colonizers are enriched in genes related to nutrient metabolism, redox balance, transcriptional regulation, and a conserved L-fucose utilization pathway experimentally shown to enhance root colonization. Not all strains succeed through the same strategy. Community-wide functional profiling revealed a distinct and reduced set of traits in the endosphere, including orthogroups associated with low-abundance strains that were overlooked in strain-level analyses. These findings reveal that multiple ecological strategies, such as metabolic competition, regulatory adaptation, and niche specialization, can support endosphere colonization. Our results advance the understanding of how bacterial colonization traits are distributed and deployed within a plant microbiome and suggest that host filtering selects for distinct, and sometimes complementary, microbial strategies. This work supports a shift toward mechanistic, genome-resolved models of microbiome assembly and offers a framework for linking microbial function to host colonization success.IMPORTANCEPlants often depend on diverse microbial partners to support their growth, resilience, and adaptation to changing environments. Among these microbes, some bacteria inhabit the rhizosphere (the narrow zone around roots where microbes interact with the plant) while others are able to enter and persist within root tissues. The traits that distinguish these two lifestyles remain poorly understood. In this study, we examined a group of related Variovorax strains from poplar tree root microbiomes to ask why some rhizosphere-associated strains also become successful endosphere colonizers. We found that strains appear to succeed through different strategies: some may benefit from rapid growth on plant-derived carbon sources, while others may rely on stress tolerance or fine-tuned regulation. These results suggest that there is no single path from the rhizosphere into the root interior, but rather multiple strategies shaped by the host environment. Understanding this diversity can inform efforts to design resilient plant-microbe communities.

Bacterial dissemination across tissues is a critically important process influencing infection outcomes. Monitoring within-host dissemination is challenging because conventional measures of bulk bacterial burden cannot distinguish between lineages that are shared between tissues and those that replicate locally. This limitation can be overcome using barcoded bacteria, where deep sequencing of the barcode locus and comparisons of barcodes between tissues define which lineages spread within the host. Numerous studies have used barcoded bacteria to generate high-resolution maps of dissemination. However, since multiple cells in the infectious inoculum can contain identical barcodes, inferences about dissemination can be confounded when distinct lineages from the inoculum with identical barcodes are observed in different tissues. Thus, even though the same barcodes can be observed in different tissues, dissemination between these tissues may not have occurred. Here, we aimed to develop an approach that would provide a solution to this confounding effect. We developed a simulation-based distance metric that quantifies the significance of observing shared barcodes between tissues. We validated this approach using simulated data sets spanning three orders of magnitude in barcode diversities and on three published experimental infection data sets. Our reanalysis reveals previously unappreciated patterns of Escherichia coli spread during liver abscess formation, clarifies the role of the Muc2 mucin in Listeria monocytogenes systemic spread, and quantifies how Klebsiella pneumoniae replication in the lungs drives systemic dissemination. As barcoding studies expand across diverse infection models, this approach provides an essential tool for accurate interpretation of within-host bacterial dissemination.IMPORTANCEHow microbes move between tissues in the host is an important factor that controls the outcome and severity of infections. A powerful method to monitor within-host microbial dissemination is the use of barcoded bacteria and lineage tracing. Comparisons of barcodes between tissues enable inferences of microbial dissemination, and this method has been applied to diverse contexts of bacterial infections. Here, we demonstrate that inferences of microbial dissemination are confounded, where observing identical barcodes in different tissues does not always signify that dissemination has occurred. To overcome this limitation, we define a metric to quantify the extent to which sharing of barcodes is meaningful and provide new insights into previous barcoding studies in Escherichia coli, Listeria monocytogenes, and Klebsiella pneumoniae. As bacterial lineage tracing continues to be applied across diverse models, our method will help ensure accurate interpretations of microbial dissemination.

Patescibacteriota is a vast lineage composed of bacteria with ultra-small size, streamlined genomes, notable defects in core metabolic potential, and symbiotic lifestyle, which are widely detected in groundwater ecosystems. Increasing attention has focused on the physiological and ecological significance of Patescibacteriota, while the potential interactions between Patescibacteriota and their phages still need more exploration. Here, we collected 82 groundwater metagenomic data sets and further derived 1,162 phages with the potential to infect 2,439 groundwater Patescibacteriota metagenome-assembled genomes (MAGs). Notably, the groundwater Patescibacteriota MAGs were predominantly infected by temperate phages, and viral operational taxonomic unit/host Patescibacteriota operational taxonomic unit (OTU) abundance ratios were significantly negatively correlated with the relative abundance of host Patescibacteriota OTUs. Intriguingly, the groundwater Patescibacteriota phages encoded various auxiliary metabolic genes (AMGs) that might promote symbiotic lifestyle and metabolic potential of host Patescibacteriota MAGs. These included AMGs associated with concanavalin A-like lectin/glucanases superfamily and O-Antigen nucleotide sugar biosynthesis, which could enhance surface adhesion of host Patescibacteriota MAGs. Moreover, AMGs related to the ABC transport system and the P-type transporter could strengthen metabolic exchange and uptake of essential nutrients from the surroundings. Additionally, AMGs involved in various metabolic pathways might alleviate metabolic deficiencies in host Patescibacteriota MAGs.

Importance: Here, we sought phages that were capable of infecting Patescibacteriota metagenome-assembled genomes (MAGs), and further explored the diversity and novelty of Patescibacteriota phages, as well as the mechanisms underlying phage-Patescibacteriota interactions in groundwater ecosystems. The abundance profiles of phage-Patescibacteriota interactions suggested that lysogenic infection may represent a mutually adapted strategy between Patescibacteriota and their phages in groundwater ecosystems. Furthermore, the groundwater Patescibacteriota phages possessed diverse auxiliary metabolic genes which might facilitate the symbiotic associations and metabolic exchange between host Patescibacteriota MAGs and other free-living microbes and expand the metabolic capabilities of host Patescibacteriota MAGs. This study elucidated the mechanisms of phage-Patescibacteriota interactions and the potential roles of phages in modulating the physiology and ecology of Patescibacteriota within groundwater ecosystems.

Marine phytoplankton are central to global seascapes, acting as key conduits in element cycling and oceanic food webs. Phytoplankton cell size spans several orders of magnitude (0.2 to >200 µm) and is an important trait that governs metabolism. However, the vast taxonomic diversity within phytoplankton size classes makes it challenging to link specific taxa to bulk community changes in productivity and elemental stoichiometry. To explore phytoplankton biogeography and biogeochemical roles in field populations, we analyzed 3 years of 16S and 18S rRNA gene amplicon sequencing variant (ASV) data alongside biochemical measurements across the dynamic latitudinal gradient of the North Pacific Transition Zone. We identified picophytoplankton community members associated with patterns in net community production (NCP), particulate organic carbon (POC), and particulate organic nitrogen (PON) and uncovered co-occurring species that may influence their growth and abundance. Multivariate linear mixed modeling revealed that the occurrence of chlorophytes explained 22.6% of NCP values, followed by stramenopiles and cyanobacteria. In contrast, POC and PON spatial patterns were best explained by chlorophyte and dinoflagellate spatial patterns. Weighted co-expression network analysis further showed NCP, POC, and PON correlations with a subset of ~40 ASVs belonging to chlorophytes, cyanobacteria, stramenopiles, haptophytes, and dinoflagellates that range in trophic strategy. Association network inference recapitulated these findings and revealed additional co-occurring phytoplankton, grazers, and heterotrophic bacteria. Together, our integrated computational analyses identified key picophytoplankton and co-occurring mixotrophs as major contributors to shaping regional biogeochemical dynamics in the North Pacific Ocean.IMPORTANCEPhytoplankton mediate key biogeochemical processes in dynamic oceanic transition zones. However, their vast cell size range and taxonomic diversity make it challenging to link specific taxa to bulk community changes in productivity and elemental stoichiometry. By integrating molecular and biogeochemical measurements from the North Pacific Transition Zone using combined network and multivariate modeling, we identified specific picophytoplankton strongly linked to community production and organic nutrients levels. These picophytoplankton included specific members of cyanobacteria, pelagophytes, haptophytes, and chlorophytes and formed tight associations with several nano- and pico-sized protistan mixotrophs, highlighting how top-down interactions and microbial consortia shape community structure and elemental fluxes. Our work establishes key microbial players that may control fundamental ecosystem processes like carbon and nitrogen cycling and offers a computational framework to track and identify "microbial neighborhoods" that underpin biogeochemical features of an ecosystem.

The inherent barriers posed by bacterial outer membranes, efflux pumps, and biofilm matrices significantly limit the clinical efficacy of antimicrobial agents, underscoring the urgent need for strategies to enhance drug penetration. Integrating pathogen-specific exogenous nutrients with conventional antibiotics has emerged as a promising approach, facilitating the targeted delivery and enhanced efficacy of antimicrobial compounds. In this study, we aimed to improve antimicrobial efficacy by enhancing transmembrane transport. First, we comprehensively compared various genome-scale metabolic reconstruction methods to identify the optimal approach. Subsequently, we enhanced our previous approach to identify exogenous nutrients by integrating topological screening, flux scoring, and chemical structure analysis. Key exogenous nutrients were identified for three pathogens: urea for Acinetobacter baumannii, acetamide for Pseudomonas aeruginosa, and succinic acid for Salmonella enterica. Growth assays confirmed that these nutrients significantly promoted bacterial proliferation. Leveraging these findings, four novel antimicrobial compounds (NC, NA, MA, and MN) were synthesized by conjugating membrane-resistant nalidixic acid or magnolol with the respective nutrients. MN enhanced the antimicrobial activity against wild-type S. enterica by 56.5%, while MA and NA boosted the activity against wild-type P. aeruginosa by 51.4% and 70.4%, respectively. Moreover, NC improved efficacy against drug-resistant A. baumannii by fourfold. These results demonstrate that conjugating exogenous nutrients with antibiotics can effectively enhance antimicrobial activity and help overcome membrane-associated resistance. This nutrient-conjugation strategy offers a promising avenue for developing new antimicrobial agents.IMPORTANCEThe difficulty of achieving effective drug penetration into bacterial cells is a major obstacle limiting antimicrobial efficacy and posing a significant global health challenge. This study demonstrates a novel strategy to combat resistance by "hijacking" nutrients that pathogens rely on for growth. By combining antibiotics with these nutrients, drugs can bypass membrane barriers and effectively reach their targets. The preferred exogenous nutrients of the high-priority pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Salmonella enterica were identified. Combining these with the existing antibiotics markedly enhanced antimicrobial efficacy against both susceptible and resistant strains. This approach offers a practical way to revitalize existing antibiotics and design new ones, potentially slowing the spread of resistance. Importantly, it highlights how understanding bacterial metabolism can lead to smarter drug design, addressing a critical need in global health.

Microbiome research using amplicon sequencing of microbial marker genes has surged over the past decade, propelled by protocols for highly multiplexed sequencing with barcoded primer constructs. Newer Illumina platforms like the NovaSeq and NextSeq series significantly outperform older sequencers in terms of reads, output, and runtime. However, these platforms are more prone to index-hopping, which limits the application of protocols designed for older platforms such as the Earth Microbiome Project protocols; hence, there is a need to adapt these established protocols. Here, we present an ultra-high-throughput amplicon library preparation and sequencing protocol (HighALPS) incorporating the capabilities of these newer sequencing platforms, designed for both 16S rRNA gene and fungal internal transcribed spacer domain sequencing. Our results demonstrate good run performance across different sequencing platforms and flow cells, with successful sequencing of mock communities, validating the protocol's effectiveness. The HighALPS library preparation method offers a robust, cost-effective, and ultra-high-throughput solution for microbiome research, compatible with the latest sequencing technologies. This protocol allows multiplexing thousands of samples in a single run at a read depth of tens of millions of sequences per sample.IMPORTANCEMarker gene amplicon sequencing on Illumina devices remains the most commonly used technology to profile microbial communities. Yet, most library preparation protocols are not adapted to harness the capabilities and deal with the caveats of the latest Illumina sequencing platforms, which highly outperform older platforms in terms of speed, quality, and output. Here, we present an ultra-high-throughput, cost-effective, and robust library preparation protocol (HighALPS) optimized to fully leverage the capabilities of the latest Illumina sequencing platforms. The combinatorial unique dual index strategy effectively combats miss-assignment of reads due to index-hopping, which is more prevalent in newer platforms. The HighALPS protocol incorporates technological (e.g., novel sequencing chemistry and lab automation platforms) as well as bioinformatics advances (e.g., denoising algorithms which make triplicate amplifications unnecessary) of the last few years to optimize and streamline library preparation for bacterial and fungal communities.

Staphylococcus aureus is a major source of community and nosocomial infections. Due to the extensive application of antibiotics, S. aureus has developed resistance to antibiotics, especially vancomycin, making clinical treatment challenging. Staphylococcal accessory regulator A (SarA) modulates S. aureus virulence by regulating the principal virulence factors. However, its role in vancomycin resistance remains largely unknown. Herein, we found that SarA not only reduces the susceptibility of S. aureus to vancomycin by directly inhibiting the expression of autolysis-related genes, but also enhances resistance to vancomycin by negatively regulating the transcription of an ATP-binding cassette (ABC) transporter, ABC-like, thereby altering the bacterial surface charge and reducing vancomycin's binding efficiency to the cell wall. Moreover, the regulation of antibiotic resistance by SarA is strain-dependent. Our study uncovers the roles of SarA in regulating vancomycin resistance, providing potential targets and ideas for the prevention and control of vancomycin-intermediate S. aureus infections.IMPORTANCEStaphylococcus aureus poses a major threat to public health due to its increasing resistance to vancomycin, a last-line antibiotic. This study reveals that Staphylococcal accessory regulator A regulates vancomycin resistance in S. aureus by suppressing genes related to autolysis and negatively regulating an ATP-binding cassette (ABC) transporter (ABC-like). This regulation of the transporter reduces the bacterial surface charge, impairing the ability of vancomycin to bind to the cell wall. These findings suggest a novel mechanism of antibiotic resistance in S. aureus and identify potential targets for combating vancomycin-intermediate S. aureus infections.