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Chemical stress drives opposing bacterial biomass responses at the single-cell level | isme

Chemical stress drives opposing bacterial biomass responses at the single-cell level | isme | RMH | Scoop.it

Microbial biomass is a central functional trait governing nutrient turnover and trophic transfer in aquatic ecosystems, yet how chemical stress reshapes biomass at the level of individual cells remains poorly resolved. Conventional toxicity assays primarily detect population-level growth inhibition and overlook sublethal physiological responses and heterogeneity within microbial populations. Here, we quantify single-cell dry-mass, a label-free proxy for cellular biomass and biosynthetic state, in the fast-growing marine bacterium Vibrio natriegens. Across thousands of cells, we assessed how exposure to copper, zinc, diclofenac, bisphenol A, bisphenol E, and bisphenol Z alters cellular biomass. Chemical stress elicited contrasting responses: copper, zinc, and diclofenac reduced median dry-mass by up to 36%, whereas bisphenols increased median dry-mass by up to 24%. These changes were not simply proportional to population-level growth inhibition. Beyond shifts in central tendency, stress altered the shape and variability of biomass distributions, revealing additional distribution-level responses that are not detectable in bulk measurements. These results identify single-cell dry-mass as an integrative trait of microbial stress physiology and show that chemical perturbations can drive opposing cellular biomass responses that are not fully captured by population growth measurements. By linking chemical stress to microbial biomass traits, this work provides a controlled framework for testing cellular-scale responses in more complex ecological settings.

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methods single cell biomass:  Cultures are grown with or without stressor in a 96 well plate while optical density is tracked. At a growth stage defined by the matched untreated control, about 3.4 hours, an aliquot is fixed in 3% paraformaldehyde. The fixed cells are diluted and settled onto a glass bottom imaging plate as a sparse layer of separated cells. They are imaged with a 100× oil objective and a wavefront camera, 60 fields per region and two regions per well, against a cell free reference. Software converts each image into a map of optical path difference, corrects the background, and outlines individual cells by thresholding and watershed, discarding debris and merged objects. For each outlined cell, dry mass is calculated as projected area times mean optical path difference divided by the refractive increment of 0.18 mL per gram. A bead derived correction factor of 0.8567 is then applied. The result is one value per cell for at least 3,000 cells per replicate, summarized as medians, spreads and distribution shapes.

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Approximate local alignment via chained MEM divergence estimation for detecting horizontal gene transfer | brvbi

Approximate local alignment via chained MEM divergence estimation for detecting horizontal gene transfer | brvbi | RMH | Scoop.it

Local alignment tools struggle at querying against thousands of bacterial genomes, because the reference indexes are memory-intensive and base-level dynamic programming is slow. We present alamem (https://github.com/yunwilliamyu/alamem), an approximate local aligner that streams unprocessed reference databases and estimates average nucleotide identity (ANI) from Maximal-Exact-Match (MEM) chaining statistics. Alamem can query a bacterial genome against >85,000 prokaryotic genomes in under 30 seconds (with multithreading) using 4 GB of memory, making it over 16x faster and 21x more memory-efficient than existing local aligners using their default running modes. On top of alamem, we built alasight (https://github.com/graceoualline/alasight) for detecting signatures of horizontal gene transfer (HGT) by finding pairs of alamem hits to divergent genomes. Alasight achieves over an order of magnitude better sensitivity on data from real bovid microbiomes than existing mobile genetic element-detection software and provides depth and sparsity information supporting each putative HGT region.

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predict hgt, 

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Advancements in biosensor Technologies for Pathogen Detection: Innovations and comparison with conventional diagnostic approaches | jmm

Rapid and accurate detection of pathogens is critical for clinical diagnosis, environmental monitoring, public health and food safety. Conventional diagnostic methods, such as culture-based, enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR), are well established and widely used due to their proven analytical performance; however, the time required for analysis, processing of samples, instrumentation, and the need for trained personnel can limit their usefulness for rapid and on-site detection. Biosensor technologies have therefore become attractive analytical platforms for the rapid and sensitive detection of pathogens. The highlights of electrochemical, optical, nanoparticle, microfluidic and paper-based biosensors and their fundamental sensing principles, design strategies, applications, merits and drawbacks are discussed in this review. Biosensors have the potential to provide benefits such as portability, multiplexing, high sensitivity, rapid detection and point-of-care use as compared with conventional diagnostic methods. The potential for pathogen detection has been increased through significant developments in nanomaterial's, bio recognition strategies, sensor design and signal-transduction mechanisms. However, the complexity of sampling, sensor stability, sensor reproductively, fabrication, scalability, and validation remain key challenges affecting their implementation in practice. This review critically discusses the current technologies used in biosensors and their application and future perspective in clinical diagnostics, food safety, and environmental monitoring with conventional diagnostic methods.
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Emerging chemical strategies for modulating protein O-GlcNAcylation | cin

Emerging chemical strategies for modulating protein O-GlcNAcylation | cin | RMH | Scoop.it
O-linked β-N-acetylglucosamine modification (O-GlcNAcylation) is an essential and dynamic post-translational modification (PTM) that modulates diverse cellular processes. Dysregulation of O-GlcNAcylation is associated with numerous human diseases, yet no O-GlcNAc-targeting therapy has been approved for clinical use, underscoring the need for tools that enable precise functional dissection of this modification. In this review, we survey emerging chemical strategies over the past two years that extend beyond conventional active-site inhibition, covering both chemically induced proximity (CIP) platforms for substrate-specific O-GlcNAc editing and non-canonical global modulators including allosteric ligands and splicing modulators. We discuss the design principles of these emerging tools, their applications in functional studies, and their current limitations. The continued evolution of these chemical approaches will accelerate the functional annotation of the O-GlcNAcome and may ultimately inform therapeutic strategies targeting O-GlcNAc dysregulation.
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Host-triggered prophage induction drives Lactiplantibacillus plantarum symbiosis through bacterial lysis

Host-triggered prophage induction drives Lactiplantibacillus plantarum symbiosis through bacterial lysis | RMH | Scoop.it
The release of bacterial bioactive molecules across the gut barrier is a crucial yet poorly understood step in host-microbe communication. Here, we identify a phage-driven mechanism associated with this process in the beneficial symbiont Lactiplantibacillus plantarum NC8 (LpNC8). We show that a stress-responsive prophage, pp2, undergoes activation and triggers holin-lysin-mediated bacterial lysis, leading to the production of infectious phage particles and increased extracellular recovery of bacterial vesicles carrying lipoteichoic acids. In a model of nutritional symbiosis, pp2-dependent lysis is required for LpNC8 to promote juvenile growth in undernourished Drosophila melanogaster. Disruption of prophage-mediated lysis impairs vesicle recovery and host growth promotion. Furthermore, we demonstrate that the copper cell region of the Drosophila midgut acts as a physiological trigger of prophage induction. Together, our findings link host intestinal physiology to prophage activity and bacterial lysis, revealing phage-driven lysis as a mechanism contributing to beneficial bacterial-host interactions during nutritional stress.
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October 8, 11:19 PM
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Technologies for engineering repetitive DNA

Technologies for engineering repetitive DNA | RMH | Scoop.it

Repetitive DNA, a fundamental architectural element of genomes, is widespread across organisms and comprises about 54% of the human genome. With advances in long-read sequencing and bioinformatics approaches, highly repetitive sequences can now be characterized in depth. Nevertheless, engineering repetitive DNA is mainly limited by repeat instability. Despite these challenges, advances have been reported in the construction of short tandem repeats and the large-scale duplication of genes. This review provides a comprehensive overview of current strategies for constructing repetitive DNA, covering both in vitro approaches, including restriction endonuclease ligation, in vitro homologous recombination, and redundancy-minimizing sequences, as well as in vivo methodologies in E. coli, Saccharomyces cerevisiae, and mammalian cells. We further discuss applications of these methods for developing genetic manipulation tools, constructing models of repetitive DNA, and synthesizing biomaterials. Future progress in engineering repetitive DNA will further advance our capabilities in designing and manipulating complex biological systems and deepen our understanding of them.

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Sustainable Overproduction of the Bacterial Pigment Indigoidine as a Natural Colorant: Stability Evaluation, Inhibition of Obesity-Diabetes-Related Digestive Enzymes, and Activation of AMPK–AKT | mbo

Sustainable Overproduction of the Bacterial Pigment Indigoidine as a Natural Colorant: Stability Evaluation, Inhibition of Obesity-Diabetes-Related Digestive Enzymes, and Activation of AMPK–AKT | mbo | RMH | Scoop.it

The increased focus on bacterial pigments can be attributed to their greater safety and eco-friendliness when compared to artificial food colorants, which can lead to severe health problems. This research was designed to optimize IND production at varying growth conditions, to assess its chemical stability, and to study its possible biological activities associated with diabetes, obesity, and insulin resistance. Medium types played an important role in both BL21-DE3 cell growth and IND production. The BL21-DE3 cell growth was maximum in PGB medium (2.76 g/L/24 h), then in LB-O medium (1.29 g/L/24 h), LB medium (1.14 g/L/24 h), and NB medium (0.94 g/L/24 h). The IND production was 75.8, 49.8, and 38.9 mg/L/24 h in LB, NB, and PGB media, respectively, while the experimental maximum IND production was achieved in LB-O medium (177.4 mg/L/24 h), which closely resembled the theoretical IND production of 180 mg/L/24 h. IND exhibited high cellular absorption properties, low cytotoxicity, and dose-dependent inhibition of α-amylase and lipase enzymes at IC50 values of 0.69 and 0.37 µg/mL, respectively. Furthermore, IND enhanced 5′-adenosine monophosphate-activated protein kinase (AMPK) and protein kinase B (AKT) signaling pathways at EC50 values of 1.36 and 4.59 µg/mL, respectively. The binding affinity of IND was also observed towards α-amylase, lipase, AMPK, and AKT enzymes via molecular docking with binding energies (BE) of −7.4, −8.1, −6.9, and −5.5 kcal/mol, respectively. All these findings were confirmed through human spermatozoa culture, where IND stimulated glucose metabolism and AMPK and AKT signaling pathways.

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October 8, 6:33 PM
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Type III effectors of symbiotic Rhizobia include diverse predicted transcriptional and post-transcriptional modulators | PLOS

Type III effectors of symbiotic Rhizobia include diverse predicted transcriptional and post-transcriptional modulators | PLOS | RMH | Scoop.it

Rhizobia are soil bacteria that establish nitrogen-fixing symbioses with legumes. While many rhizobia use a Type III Secretion System to deliver “Nodulation Outer Protein” (Nop) effectors, some uniquely use these proteins to initiate nodule organogenesis, bypassing classical signalling. The molecular functions of these effectors remain largely unknown due to extreme sequence divergence. Using AlphaFold2-mediated structural proteomics, we identified a modular architecture in rhizobial effectors composed of 22 distinct structural units. We reveal that many Nop effectors are cryptic transcriptional or post-transcriptional regulators, harbouring unrecognised nucleic acid–binding modules and RNA-dependent RNA polymerase domains. Crucially, these modules are conserved in specific plant pathogens, such as gall-inducing Pantoea, where our predicted structural units align with experimentally validated DNA-binding domains. Furthermore, we discovered the BPN (B3 and PUA-like nucleic acid binding) domain as a structural mimic of plant B3-domain transcription factors, pointing to a direct mechanism for hijacking legume development. Our findings strongly suggest that rhizobia employ a modular domain-fusion strategy to act as direct genetic modulators, uncovering a conserved mechanism used by both symbionts and pathogens to hijack host developmental programmes.

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inter kingdom

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October 8, 6:22 PM
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iModulonMiner 2.0: multi-modality modularization of prokaryotic bulk, single-cell, and community omics data | nar

iModulonMiner 2.0: multi-modality modularization of prokaryotic bulk, single-cell, and community omics data | nar | RMH | Scoop.it

Prokaryotic gene expression datasets, including single-cell transcriptomics and community meta-transcriptomics, are growing rapidly, opening discovery opportunities while creating new analytical challenges. Module detection methods, such as independent component analysis, are powerful tools for expression analysis focused on identifying coordinated gene programs that consistently appear within gene expression compendia. Here, we present iModulonMiner 2.0, an end-to-end expression module detection workflow that adds five main capabilities to address emerging multi-dataset, multi-strain, and multi-modality challenges. First, it expands from bulk RNA-seq to support single-cell RNA-seq, community meta-transcriptomics, and multi-omics datasets, along with a standardized data pipeline. Second, it adapts multi-view learning to identify signals that are shared versus context-specific across strains, species, and modalities, supporting cross-context comparison and integration. Third, it provides new robust and prior-guided single-compendium inference methods. Fourth, it adds post-processing diagnostics for interpretability. Fifth, it supports multi-scale transfer of regulatory knowledge from bulk compendia to other modalities. Available as open-source software, iModulonMiner 2.0 provides a unified, module-based workflow for interpreting diverse prokaryotic expression compendia across modalities and biological scales.

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palsson bo, tool decomposes a large collection of expression samples into two parts: a set of gene modules whose members move together, and the activity of each module across samples. The decomposition is unsupervised, requiring no labels or prior regulator list, so modules emerge as unnamed gene sets that must be matched to known biology afterward. Version 2.0 adds a pipeline that builds a compendium from public NCBI data given only an organism name, and a multi-view method that decomposes several datasets jointly, separating signals shared across them from signals specific to one. This supports comparison of regulatory structure between strains or species, pairing of transcriptomics with proteomics to locate where the two decouple, and interpretation of single-cell or community data against modules learned from bulk compendia. Added diagnostics include a confidence score that flags cases where an apparent module activity shift is driven by a few genes rather than the whole set.

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Selecting for lysis in a temperate phage population | brve

Selecting for lysis in a temperate phage population | brve | RMH | Scoop.it

Temperate phages represent an abundant source of phage diversity, but their capacity for lysogeny limits their therapeutic potential. Here, we asked whether repeated selection for lytic replication could drive a temperate phage toward an obligately lytic lifestyle. We serially propagated a cocktail of three temperate coliphages using a modified Appelmans’ protocol in which phage populations were independently passaged on eight E. coli hosts. Whole-genome sequencing revealed substantial changes in population composition and mutation frequencies. The Uetakevirus phage 1362 was undetectable after the first round, whereas the closely related P2-like phages in the cocktail dominated the evolving populations. Mutations repeatedly accumulated in lysis- and lysogeny-associated genes. Longitudinal genomic analysis revealed rapid fixation of mutations in the integrase coding region, while variants in lysA, lysB, and holin increased in frequency over successive rounds of selection. Protein structure modeling localized selected mutations to regions with potential functional significance. These include the DNA-binding domain of integrase and a surface-exposed region of LysA. Together, these results show that sustained selection for lytic replication can drive rapid and repeatable genomic adaptation in temperate phage populations.

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Engineering anaerobic fungal–bacterial consortia for direct conversion of lignocellulosic biomass into medium-chain fatty acids | Tin

Engineering anaerobic fungal–bacterial consortia for direct conversion of lignocellulosic biomass into medium-chain fatty acids | Tin | RMH | Scoop.it
Lignocellulosic biomass is a renewable feedstock for sustainable fuels and chemicals, yet industrial conversion remains constrained by carbohydrate solubilization. Inspired by herbivore rumen microbiomes, we engineered an anaerobic fungal–bacterial consortium that converts native lignocellulose into medium-chain fatty acids (MCFAs) without pretreatment. Systematic screening identified the anaerobic fungus isolated here, Neocallimastix sp. FC1, together with Megasphaerahexanoica, as a top-performing consortium, achieving a lignocellulose-to-MCFA yield of 21.0% (carbon-to-carbon basis) through tight lactate cross-feeding without competition for soluble sugars. Fungal lactate production limited the growth of M. hexanoica in co-culture, and the bacterium reallocated protein from growth toward chain elongation, resulting in increased MCFA production. These findings identify fungal lactate production as the primary biological constraint, and balancing lactate production and consumption as a key engineering strategy for improving lignocellulose-to-MCFA conversion. Techno-economic analysis identified high cultivation medium costs as the primary economic constraint and established quantitative cost–yield targets for profitable MCFA production.
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3st, Milled reed canary grass (Phalaris arundinacea) at 10 g/L, through a 1 mm screen, untreated. For the proteomics experiments they switched to milled sorghum

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October 8, 11:57 AM
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Arabidopsis uses distinct coumarins and bacterial pathways for pH-adaptive iron acquisition | CEL

Arabidopsis uses distinct coumarins and bacterial pathways for pH-adaptive iron acquisition | CEL | RMH | Scoop.it
Iron (Fe) limitation restricts plant growth in diverse soils, and root-associated microbes can alleviate plant Fe starvation. Whether plants integrate the edaphic environment and microbial activities into their Fe uptake strategies remains unclear. We show that bacterium-mediated alleviation of Fe deficiency in Arabidopsis functions at varying environmental pH and is taxonomically widespread among root microbiota isolates from soils with different edaphic profiles. This process is regulated by host-controlled and pH-adapted root exudation of different coumarin chemotypes. These exometabolites interact with root-associated bacteria to mobilize Fe either via bacterial siderophore-mediated chelation at circumneutral pH or redox-sensing-controlled, reduction-based pathways at acidic pH. The corresponding bacterial genes are prevalent in the root microbiota, and they likely evolved before the emergence of land plants. Our findings suggest that Fe malnutrition-induced exudation of redox-active metabolites by non-graminaceous plant species is a widespread adaptation for Fe mobilization from soil, mediated by the co-option of ancient microbial processes.
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At pH 7.4, pyoverdine pulls ferric iron off insoluble precipitates. fraxetin then takes the iron from pyoverdine by ligand exchange. Root FRO2 reduces the fraxetin bound ferric iron, and IRT1 (high affinity iron importer in Arabidopsis roots) imports it. At pH 5.7, sideretin reduces ferric iron to ferrous iron and is oxidized to its quinone form in the process. The bacteria are proposed to import the quinone via TonB and ExbB, reduce it back with quinone oxidoreductases, and export it via MexH and MexI. The regenerated sideretin then reduces more iron. The bacteria act as a recycler of the reductant, which is why live cells and the RoxSR system are needed. The resulting ferrous iron goes straight to IRT1, which is why FRO2 becomes dispensable. This shuttle is a model based on transcriptomics and is not yet validated.

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October 8, 11:42 AM
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Chemical stress drives opposing bacterial biomass responses at the single-cell level | isme

Chemical stress drives opposing bacterial biomass responses at the single-cell level | isme | RMH | Scoop.it

Microbial biomass is a central functional trait governing nutrient turnover and trophic transfer in aquatic ecosystems, yet how chemical stress reshapes biomass at the level of individual cells remains poorly resolved. Conventional toxicity assays primarily detect population-level growth inhibition and overlook sublethal physiological responses and heterogeneity within microbial populations. Here, we quantify single-cell dry-mass, a label-free proxy for cellular biomass and biosynthetic state, in the fast-growing marine bacterium Vibrio natriegens. Across thousands of cells, we assessed how exposure to copper, zinc, diclofenac, bisphenol A, bisphenol E, and bisphenol Z alters cellular biomass. Chemical stress elicited contrasting responses: copper, zinc, and diclofenac reduced median dry-mass by up to 36%, whereas bisphenols increased median dry-mass by up to 24%. These changes were not simply proportional to population-level growth inhibition. Beyond shifts in central tendency, stress altered the shape and variability of biomass distributions, revealing additional distribution-level responses that are not detectable in bulk measurements. These results identify single-cell dry-mass as an integrative trait of microbial stress physiology and show that chemical perturbations can drive opposing cellular biomass responses that are not fully captured by population growth measurements. By linking chemical stress to microbial biomass traits, this work provides a controlled framework for testing cellular-scale responses in more complex ecological settings.

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methods single cell biomass:  Cultures are grown with or without stressor in a 96 well plate while optical density is tracked. At a growth stage defined by the matched untreated control, about 3.4 hours, an aliquot is fixed in 3% paraformaldehyde. The fixed cells are diluted and settled onto a glass bottom imaging plate as a sparse layer of separated cells. They are imaged with a 100× oil objective and a wavefront camera, 60 fields per region and two regions per well, against a cell free reference. Software converts each image into a map of optical path difference, corrects the background, and outlines individual cells by thresholding and watershed, discarding debris and merged objects. For each outlined cell, dry mass is calculated as projected area times mean optical path difference divided by the refractive increment of 0.18 mL per gram. A bead derived correction factor of 0.8567 is then applied. The result is one value per cell for at least 3,000 cells per replicate, summarized as medians, spreads and distribution shapes.

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October 8, 9:10 AM
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Toward interpretable foundation models for molecular biology | mcell

For machine learning models in molecular biology, explanation is as important as prediction. Encoding prior knowledge and treating interpretability as a first-class design objective accomplish both. We provide design elements and a checklist for the next generation of foundation models in molecular biology that are as interpretable as they are powerful.
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Research progress on Bacillus subtilis expression systems and effects of different promoters on expression efficiency | jmm

Research progress on Bacillus subtilis expression systems and effects of different promoters on expression efficiency | jmm | RMH | Scoop.it
This review systematically summarizes the features of Bacillus subtilis expression systems, the regulatory effects of various promoters on heterologous expression efficiency, and rational modification strategies of promoter core regions. B. subtilis WB600 or WB800 are the preferred hosts for autonomous plasmid-based expression systems due to their multiple protease deletions, which reduce recombinant protein degradation. In contrast, wild-type strains are more suitable for chromosomal integration systems because of native genomic background and physiological characteristics, which are advantageous for long-term stable expression. Constitutive promoters are suitable for stable and large-scale industrial enzyme production, while inducible promoters realize accurate and tunable control of gene expression. Dual promoters can effectively enhance transcription and protein yield, but are not universally superior to single promoters, and the final expression efficiency mainly depends on the downstream promoter adjacent to the target gene. Core region modification, such as optimizing the consensus sequences of the −35 and − 10 regions and adjusting the spacer length, can significantly improve promoter strength and consequently protein expression. The coordinated optimization of host-promoter-critical elements is critical to achieve highly efficient expression of target products. This review provides a theoretical basis for the further development and application of B. subtilis expression systems, offering valuable references for the rational development of high-efficiency promoter engineering strategies and heterologous gene expression optimization.
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Phage phenotyping by measuring plaque expansion dynamics | brvm

Phage phenotyping by measuring plaque expansion dynamics | brvm | RMH | Scoop.it

Bacteriophages exhibit staggering genomic diversity, yet phenotypic characterization remains bottlenecked by assays that generally yield simple binary infection outcomes. Quantitative traits can be extracted from standard liquid cultures, but many phages fail to produce a measurable effect in these settings, necessitating an improved quantitative approach on semi-solid media. While end-point plaque size is commonly used for quantitative phenotyping, it only provides a static snapshot that fails to disentangle phage performance across changing bacterial growth phases. Here, we report a cost-effective, scalable method to quantify the bacterial killing rates of diverse phages by continuously tracking plaque development using a consumer-grade flatbed scanner and custom open-source computer vision software. By fitting a minimal, five-parameter phenomenological model to the diverse BASEL collection of Escherichia coli phages, we accurately captured plaque expansion dynamics across all bacterial growth phases. We discovered that plaque expansion parameters vary significantly across individual phages and taxonomic families, with the initial expansion rate demonstrating an inverse correlation with viral genome size. Notably, these plaque expansion dynamics did not correlate with bacterial collapse times in liquid culture, indicating that they represent distinct physiological and kinetic processes. Finally, we demonstrated that phage taxonomic family can be predicted with 72.1% accuracy solely from dynamic plaque parameters using a random forest classifier, whereas conventional endpoint plaque sizes held no predictive power. This time-lapse phenotyping approach yields robust kinetic data superior to end-point measurements, establishing a scalable platform to accelerate phage discovery and genotype-phenotype mapping.

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diy 

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Native pathogen-phage networks reveal multilayered defense and gut-active anti-phage immunity | chm

Native pathogen-phage networks reveal multilayered defense and gut-active anti-phage immunity | chm | RMH | Scoop.it
Bacteriophages drive pathogen evolution, yet the mechanisms governing phage susceptibility in native bacterial backgrounds, and their consequences within mammalian hosts, remain poorly understood. Here, we mapped >1,000 interactions between 20 diverse Salmonella isolates and 52 wild phages from global disease reservoirs, integrating genome-scale fitness profiling with comparative genomics. Receptor identity and surface phase variation, including Hin-mediated flagellar switching, explained ∼67% of phage susceptibility patterns, identifying cell-surface architecture as the major determinant of phage host range in Salmonella. Among resistance phenotypes not explained by surface features, we discovered anti-phage-packaging agent (AppA), a prophage-encoded defense factor that abrogates phage replication within its native host. AppA inhibits phage DNA packaging through functional mimicry of a terminase assembly interface, revealing a previously unrecognized mechanism of phage defense. AppA is expressed under conditions encountered during mammalian infection and suppresses phage expansion in the murine gut, demonstrating that prophage-encoded single-gene defenses can shape disease outcomes in vivo.
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October 8, 11:26 PM
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Integrative machine learning approaches for enzyme kinetic parameter prediction | bft

Integrative machine learning approaches for enzyme kinetic parameter prediction | bft | RMH | Scoop.it

The prediction of enzyme kinetic parameters, particularly kcat and Km, is rapidly evolving from physics-based modeling toward datadriven artificial intelligence (AI) approaches, driven by expanding biochemical databases and advances in machine learning (ML) and deep learning (DL). We focus on AI-based enzyme kinetic parameter prediction, with an emphasis on kcat and Km, while also considering related parameters, such as Ki and kcat/Km. The key findings reveal that: (i) Representation learning increasingly relies on pretrained protein language models, while structural embeddings often show limited additional performance gains over sequence-based approaches; (ii) Model performance is highly data-dependent: classical ML regressors can outperform DL architectures on small datasets when using comparable feature representations, though multimodal feature integration can improve generalization; and (iii) Multitask frameworks for the joint prediction of kcat and Km may provide synergistic benefits, although the magnitude of the improvement may be limited. Future progress will require standardized benchmarks, mechanistically informed model architectures, uncertainty-aware prediction, and robust out-of-distribution validation to improve biochemical relevance, interpretability, and real-world utility

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Advances in large DNA fragment assembly for microbial cell factory engineering

Advances in large DNA fragment assembly for microbial cell factory engineering | RMH | Scoop.it

The efficient, rapid, and reliable assembly of DNA fragments is essential for advancing metabolic engineering and synthetic biology. With the rapid advancement of DNA synthesis and assembly technologies, the scale of DNA assembly has expanded from single genes to metabolic pathways and even genomes. Large DNA fragment assembly, in particular, has developed into a pivotal tool for microbial cell factory engineering, significantly contributing to the understanding and construction of biological systems. This review summarizes recent advancements in large DNA fragment assembly methods, encompassing in vitro and in vitro methods for multiple-gene assemblies, as well as genome-scale technologies, including synthetic genome and neochromosome construction. We systematically compare their key features in terms of assembly principle, capacity, and efficiency. Especially, we highlight their applications in microbial cell factory engineering, including heterologous pathway construction, reprogramming host metabolism, and expanding complex biosynthetic networks. Finally, we discuss the challenges and prospects of applying large DNA fragment assembly to advance cell factories. In summary, this review provides a theoretical and technical framework for engineering high-performance microbial cell factories, contributing to the advancement of industrial biomanufacturing. cloning, genome editing

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A membrane-free spot-plating protocol for Agrobacterium-mediated transformation of diverse yeasts | PLOS

A membrane-free spot-plating protocol for Agrobacterium-mediated transformation of diverse yeasts | PLOS | RMH | Scoop.it

Agrobacterium-mediated transformation (AMT) is a critical method for genetic manipulation of non-model fungi, yet it remains a laborious and inefficient technique. When co-cultured in acetosyringone-supplemented induction medium, Agrobacterium transfers DNA directly into yeast cells using its virulence machinery. Membrane filters are commonly used to support the co-culture of yeast and Agrobacterium on agar plates, however some reports demonstrate that these filters are unnecessary for specific yeast species. Here we confirm across diverse budding yeasts that membrane filters are not necessary for effective AMT. Concentrating the cells via centrifugation and “spotting” the cell pellet directly onto the induction medium proved effective. This reduces hands-on time to 15 minutes and eliminates filter cost. In the oleaginous basidiomycete yeast, Rhodotorula toruloides, this simplified method increases transformation efficiency by 66% to 2,500 transformants per 106 recipient cells. We further optimized the Agrobacterium:Rhodotorula cell ratio and culture resuspension volume to achieve more than 200,000 CFU per transformation representing a 2–3 fold improvement over previously implemented protocols. This spot-plating method was successfully applied to seven yeast species of a distantly related phylum, Ascomycota, including one for which genetic transformation has not previously been reported, Botryozyma nematodophila. This approach highlights the broad applicability of the spot-plating methods across diverse yeast systems. Furthermore, this method could facilitate high-throughput transformation workflows that are critical for genome-scale functional studies.

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Genome-wide synthetic lethality screen of Bam complex-associated genes in Escherichia coli | eLife

Genome-wide synthetic lethality screen of Bam complex-associated genes in Escherichia coli | eLife | RMH | Scoop.it

Biogenesis of the bacterial outer membrane is key to bacterial survival and antibiotic resistance. Central to this is the β-barrel assembly machine (Bam) complex and its associated chaperones, which are responsible for transport, folding, and insertion of outer membrane proteins (OMPs). The E. coli Bam complex is composed of two essential subunits, BamA and BamD, and three non-essential accessory lipoproteins, BamB, BamC, and BamE. Optimal Bam function is further dependent on the non-essential periplasmic chaperones DegP, Skp, and SurA. Despite intensive study, the specific function of these non-essential Bam-associated proteins is not fully understood. Here, we analysed ΔbamB, ΔbamC, ΔbamE, ΔsurA, Δskp, and ΔdegP knockout strains by phenotypic screening, conservation analysis and high-throughput genetics. We identified hundreds of synthetic-lethal interactions and revealed that Bam complex activity is impacted by changes in outer membrane lipid composition and that enterobacterial common antigen is essential in the absence of the chaperone SurA. We also show that genes responsible for synthesis of peptidoglycan are synthetically lethal with Bam accessory lipoprotein encoding genes. Together, our data indicate potential mechanisms for coordination of OMP biogenesis with other cellular growth processes, such as LPS and peptidoglycan biogenesis.

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October 8, 5:55 PM
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REFinder: Mining new enzymes from metagenomes | brvai

REFinder: Mining new enzymes from metagenomes | brvai | RMH | Scoop.it

Microbial metagenomes encode vast catalytic diversity, but recovering enzymes of novel, yet-undescribed functionality typically requires whole-community assembly plus a means of identifying active proteins ab initio. The first step of the task is compute-intensive and misses low-abundance sequences. The second is complicated by our inability to predict novel functions. REBEAN, our DNA language model, sidesteps the latter by assigning each sequencing read a high-level Enzyme Commission (EC) class or a non-enzyme label without alignment. Here we build REFinder, a pipeline that addresses both steps by routing REBEAN-annotated reads to assemble only the putative enzymatic reads that have identified catalytic signatures. In our evaluation of 50 microbiome metagenomes, REFinder identified 1.2 to 2.1 fold more enzymes than could be recovered via homology-based annotation of the proteins from the corresponding full assemblies. Moreover, it was as much as 6.4-fold cheaper computationally than full assembly. Across all samples, REFinder identified at least three fourths and as many as 90% of the homology-accessible enzymes identified via full assembly of the complete metagenomes. Notably, a fraction of these, 22% to 45% per EC class, carried no similarity to Swiss-Prot proteins, i.e. a set of enzymes homology cannot annotate. For roughly two fifths of the over thirteen thousand such novel oxidoreductases from two saliva samples, ESMFold predicted structures aligned with TM-score≥0.7 to a characterized enzyme structure in the PDB - a substantial structural similarity without sequence homology. These results illustrate that targeted, alignment-free assembly turns even well-mapped microbiomes into a source of thousands of previously invisible but credible novel enzymes, raising our expectations for exploration of environmental microbiomes.

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for enzyme discovery from an uncultured environmental metagenomic reads (not even assembled, just reads).

for the next step 1. ESMFold structure prediction, then structure search against EC-annotated PDB chains.  2. Pfam HMM search. Mapped 77.5% of those 13,745 to domain families, 69.8% known and 7.7% domains of unknown function.  3. MebiPred for metal-binding potential. Relevant for redox enzymes.   4. Reliability scoring of the protein embedding.   5. DIAMOND against Swiss-Prot or TrEMBL to get a full EC number when there is a hit.

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October 8, 5:24 PM
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Unlocking the full potential of spatial omics in plants: practical challenges, solutions, and a path forward | tpc

Unlocking the full potential of spatial omics in plants: practical challenges, solutions, and a path forward | tpc | RMH | Scoop.it

Spatial omics technologies provide new opportunities for plant biology by enabling molecular profiling within structurally intact tissues, revealing spatially organized cell states, developmental gradients, and regulatory interactions. While spatial transcriptomics has driven early advances, the field is rapidly expanding toward integrated spatial multi-omics by combining single-cell and spatial transcriptomic, epigenomic, proteomic, and metabolomic data. These approaches offer new opportunities to study development, physiology, and plant biotic and abiotic interactions in spatially preserved cellular contexts. However, despite rapid adoption, the field remains constrained by plant-specific challenges when applying technologies largely developed for animal systems. Compared with animal systems, plant tissues pose additional challenges due to rigid cell walls and diverse chemistries, complicating sample preparation, cell and subcellular segmentation, signal detection, and data integration. As a result, many studies rely on bespoke protocols and analysis pipelines that are often difficult to reproduce or generalize. Here, we provide a practical, solution-oriented synthesis of current bottlenecks across experimental and computational pipelines, highlight emerging strategies to overcome these limitations, and propose a roadmap for community-driven protocol sharing, benchmarking, and integration across spatial and multi-omics modalities. Addressing these challenges will be essential to establish spatial omics as a routine and scalable tool for plant biology.

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October 8, 12:00 PM
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EPBAM: annotation-robust detection of alternative splicing events and a systematic benchmarking of current tools | bft

EPBAM: annotation-robust detection of alternative splicing events and a systematic benchmarking of current tools | bft | RMH | Scoop.it

Alternative splicing (AS) is a major driver of transcriptomic diversity, yet its computational analysis remains challenged by inconsistent event definitions across tools and by the sensitivity of quantification methods to annotation quality. Here, we present a comprehensive benchmark of seven AS detection tools—replicate Multivariate Analysis of Transcript Splicing (rMATS), Super-fast Pipeline for alternative splicing analysis, version 2 (SUPPA2), Modeling Alternative Junction Inclusion Quantification + Visualization Of Inferred Local splicing Alternatives (MAJIQ+VOILA), EventPointerST (EPST), Shiba, LeafCutter, and the newly introduced EventPointer BAM (EPBAM)—evaluated across three complementary datasets: reverse transcription PCR (RT-PCR) validated experiments, simulated data, and Lexogen Spike-In RNA Variant (SIRV). The inclusion of SIRV, which provide experimentally derived sequencing data with fully controlled ground truth, is central to our evaluation framework, enabling rigorous assessment of quantification accuracy under real technical conditions. We assess tool performance under three annotation scenarios—complete, incomplete, and overloaded—reflecting the annotation uncertainty commonly encountered in practice. EPBAM extends the EventPointer framework by enabling de novo event detection coupled with a coverage-corrected Ψ quantification strategy. Our results demonstrate that annotation quality substantially drives tool performance: annotation-dependent tools achieve peak accuracy under complete annotations, whereas EPBAM exhibits the most robust and consistent behaviour across annotation conditions, recovering unannotated events with low false discovery rates. No single tool dominates across all evaluation metrics, highlighting the importance of dataset diversity and standardized benchmarking practices for meaningful tool comparison in the AS field.

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October 8, 11:48 AM
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An AI-enabled proteome-scale framework for identifying sustainable protein alternatives for future food systems | npj

An AI-enabled proteome-scale framework for identifying sustainable protein alternatives for future food systems | npj | RMH | Scoop.it

Identifying sustainable alternatives to animal proteins is a central challenge for global food system transformation. Replacing animal proteins requires preserving food functionalities—such as gelation, foaming, and emulsification—that arise from the collective behavior of heterogeneous protein mixtures within food matrices. While these properties are assessed experimentally at the ingredient level, systematically comparing the vast diversity of natural proteins remains difficult, and most artificial intelligence (AI)-based protein models focus on individual proteins rather than proteome-level behavior. Here, we present AlterProtX, an AI-enabled framework that integrates molecular- and proteome-scale features to guide alternative protein discovery. AlterProtX predicts protein thermal stability, a processing-relevant property, and integrates it with six intermolecular interaction attributes into distribution-based proteome representations. This multiscale approach enables mechanistic comparison between animal and non-animal proteomes, revealing molecular features underlying functional similarity and divergence. By integrating allergenic potential and nutritional adequacy, AlterProtX supports early-stage prioritization of candidate protein sources and provides an interpretable platform for proteome-level evaluation of food proteins.

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October 8, 11:32 AM
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Intragenomic conflict between transformation and prophage explains taxon-specific DNA acquisition | isme

Intragenomic conflict between transformation and prophage explains taxon-specific DNA acquisition | isme | RMH | Scoop.it

The activation of many chromosomally integrated mobile genetic elements by RecA-DNA nucleoprotein filaments may represent an adaptation to evading deletion through homologous recombination. Consistent with bacterial transformation facilitating such eliminations of inserted viral DNA, cross-taxa comparisons found isolates’ prophage content was negatively associated with homologous recombination rates. Assaying the effect of the composition of the extracellular DNA pool on transformation of a lysogen demonstrated that DNA from conspecific donors drove both prophage activation and deletion, whereas DNA originating from different species triggered only prophage activation. Accordingly, rates of horizontal DNA transfer mechanisms varied across bacterial ecologies, with homologous recombination common relative to prophage accumulation when DNA originated from fewer donor species.

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1str

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