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Fast and flexible minimizer digestion with digest.

Minimizer digestion is an increasingly common component of bioinformatics tools, including tools for De Bruijn-Graph assembly and sequence classification. We describe a new open source tool and library to facilitate efficient digestion of genomic sequences. It can produce digests based on the related ideas of minimizers, modimizers or syncmers. Digest uses efficient data structures, scales well to many threads, and produces digests with expected spacings between digested elements. Digest is implemented in C++17 with a Python API, and is available open-source at https://github.com/VeryAmazed/digest.

digestion

Fast and flexible minimizer digestion with digest.

SUMMARY: Minimizer digestion is an increasingly common component of bioinformatics tools, including tools for de Bruijn graph assembly and sequence classification. We describe a new open source tool and library to facilitate efficient digestion of genomic sequences. It can produce digests based on the related ideas of minimizers, modimizers or syncmers. Digest uses efficient data structures, scales well to many threads, and produces digests with expected spacings between digested elements. AVAILABILITY AND IMPLEMENTATION: Digest is implemented in C++17 with a Python API, and is available open-source at https://github.com/VeryAmazed/digest. The python library is available on Bioconda. Rust bindings are available as a public crate at https://crates.io/crates/digest-rs.

Software

Genomic profiling of digestion related enzymes in Anopheles aquasalis a major coastal neotropical malaria vector.

Digestive genes are fundamental for the development and survival of mosquitoes and can serve as a target for the development of strategies for mosquito control or vector-borne disease prevention. Genes related to digestion were identified in the genome of the neotropical malaria vector Anopheles aquasalis by similarity. We used reciprocal BLAST with annotated digestion proteins for Anopheles gambiae. Orthology and evolutionary analyses were performed using MEGA with a bootstrapped phylogenetic tree constructed by the neighbor-joining method, and copy number variation was measured by the standard deviation of the average copy number in each gene family. We identified 241 genes related to digestion in An. aquasalis: 56 genes related to carbohydrate digestion, 51 genes for lipid digestion, and 134 genes for protein digestion. Phylogenetic relationships with other anophelines show that An. aquasalis genes are closely related to those of neotropical mosquitoes Anopheles darlingi and Anopheles albimanus. Orthologous gene clusters are conserved in important families of all four species. Some of these conserved genes are of interest for studies on controlling mosquito vectors, such as larvicidal toxin receptor genes, alpha-amylase, alpha-glucosidase, and maltase; important target genes for transmission-blocking vaccines, such as aminopeptidase N1 and carboxypeptidase B; and the major intestinal serine proteases, such as trypsins and chymotrypsins, which can positively or negatively affect Plasmodium development in the midgut. These data provide a better understanding of digestion-related genes in American anopheline mosquitoes and may support further fundamental and applied studies aimed at malaria control.

Animals

Protein isolation markedly enhances in vitro digestibility, nutritional quality, and bioactivity of fungal mycelial proteins.

Fungal mycelial proteins are promising sustainable protein sources, yet their nutritional utilization is often limited by structural constraints. This study systematically evaluated the effects of protein isolation on the proteomic composition, gastrointestinal digestion behavior, amino acid utilization, and bioactivity of Pleurotus citrinopileatus mycelial proteins. Quantitative proteomics identified 3591 proteins, of which 3374 were shared between mycelial flour (PCMF) and protein isolate (PCMPI), indicating that PCMPI primarily represents the soluble proteome fraction. In vitro digestion revealed that PCMPI exhibited significantly higher digestibility (93.98%) than PCMF (42.98%) (p&#xa0;<&#xa0;0.05), reaching levels comparable to whey protein isolate. Enhanced enzymatic accessibility in PCMPI promoted rapid peptide generation during the gastric phase and efficient amino acid release during the intestinal phase, resulting in higher peptide (634.76&#xa0;mg/g) and free amino acid levels (341.69&#xa0;mg/g) at the digestion endpoint. Consequently, PCMPI achieved a balanced amino acid profile with a PDCAAS of 1.0. Moreover, its digestion products exhibited stronger antioxidant activity (IC&#x2085;&#x2080;&#xa0;=&#xa0;8.36&#xa0;mg/mL) and ACE inhibitory activity (IC&#x2085;&#x2080;&#xa0;=&#xa0;15.65&#xa0;mg/mL) compared with PCMF. Mechanistically, protein isolation disrupted the cell wall matrix, shifting digestion from a structure-limited to an accessibility-driven regime. Collectively, these findings demonstrate that protein isolation markedly enhances the digestibility, nutritional quality, and functional potential of mycelial proteins, supporting their application as high-value sustainable protein ingredients.

Digestion

Integrated metagenomic and metaproteomic insights into current-carrying-coil magnetic field enhanced synergistic methanogenic system and antibiotic resistance gene reduction in cow manure anaerobic digestion.

Anaerobic digestion (AD) is a sustainable strategy for valorizing cow manure (CM). However, the high ammonia (NH3) concentration and low biodegradability of CM limit hydrolysis and methane production. This study investigated the application of a current-carrying-coil-based magnetic field (CCC-MF) to AD of CM. The CCC-MF digesters showed higher soluble chemical oxygen demand and attained 16.59&#xa0;% higher ammonium nitrogen reduction, contributing to a 37.50&#xa0;% higher average methane yield than the control. Further, CCC-MF digesters showed higher enzyme activities (alkaline protease&#xa0;+&#xa0;30&#xa0;%, acetate kinase&#xa0;+&#xa0;22&#xa0;% and hydrazine dehydrogenase&#xa0;+&#xa0;26&#xa0;%) and increased microbial metabolic indices (dehydrogenase activity&#xa0;+&#xa0;17&#xa0;% and electron transport system activity&#xa0;+&#xa0;10&#xa0;%) than the control. Metagenomics analysis revealed that abundances of the bacterial genera Mesotoga, Aminobacterium, Xiashengella, unclassified Candidatus Cloacimonadota, Advenella, Pseudomonas, and Comamonas increased, whereas the acetoclastic methanogen Methanothrix decreased by 2.58&#xa0;%, accompanied by 2.07- and 1.64-fold increases in hydrogenotrophic methanogens Methanospirillum and Methanobacterium, respectively, in CCC-MF digesters. The abundance of nitrogen dissimilation and assimilation genes NirK, NorB, NarB, NapA, nmo, and GLT1 were enhanced by 1.14, 1.04, 2.30, 1.32, 1.17, and 1.29-fold in CCC-MF digesters compared to the control. Moreover, metaproteomics revealed higher up-regulated differentially expressed proteins in NH3 reduction-related amino acid metabolism pathways in CCC-MF digester compared to control. Additionally, reduced abundances of bacitracin, polymyxin, sulfonamide, and multidrug antibiotic resistance (MAR) gene types were observed in the CCC-MF digesters. The findings suggest that applying CCC-MF may be associated with higher methane production and ammonium reduction, potentially linked to a more favorable synergistic methanogenic system and nitrogen transformation pathways.

Manure

Gastrointestinal digestion governs insect protein hydrolysis and predicted bioactive peptide release: Species-dependent implications for functional food applications.

This study investigates the digestion of insect proteins and the release of predicted bioactive peptides during human gastrointestinal digestion. Using the Infogest in vitro model, mealworm, cricket, and black soldier fly larvae (BSFL) proteins were digested and analyzed through discovery proteomics and bioinformatics to identify predicted bioactive peptides. Sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) quantified insect proteins including predicted bioactive peptide precursor proteins, the precursors of predicted bioactive peptides. Results indicated that gastrointestinal digestion strongly influences peptide release, with the gastric phase exhibiting a richer predicted bioactive peptide profile than the small intestinal phase. Many predicted bioactive peptides were rapidly hydrolysed under small intestine conditions, which may lead to reduced stability or diminished activity in vivo, potentially explaining why certain peptides show strong bioactivity in vitro but limited effects in vivo. Additionally, predicted bioactive peptide release varied by insect species, influenced by genetic factors and peptide abundance. These findings highlight the importance of species selection and consideration of proteolytic digestion patterns in optimizing insect-derived bioactive peptides for functional foods and nutraceutical applications.

Animals

Insights into the fate and dynamics of antibiotic resistance in multidrug-resistant Bacillus cereus during in vitro simulated gastrointestinal digestion.

Bacillus cereus, an important pathogen responsible for causing foodborne diseases worldwide, releases pore-forming enterotoxins, which target host epithelial cells, leading to osmotic lysis and ultimately manifesting as diarrheal syndrome. Moreover, some B. cereus strains carry antimicrobial resistance genes that confer multidrug resistance against a spectrum of antibiotics. Characterizing the survival traits of multidrug-resistant (MDR) B. cereus strains in the intestinal microenvironment is essential for developing targeted strategies to effectively manage diarrheal foodborne diseases caused by this pathogen. This study used whole-genome sequencing (WGS) to evaluate the pre- and post-digestion toxigenic potential, antimicrobial resistance profiles, and genetic diversity of MDR B. cereus strains isolated from food samples in Guangdong Province, China. The four B. cereus isolates investigated in this study exhibited a genetic diversity, as determined by multilocus sequence typing analysis of WGS data. All four isolates produced the diarrheal toxins Hbl, Nhe, and CytK to varying levels, indicative of their potential to cause outbreaks of foodborne diseases. Each of the four isolates exhibited resistance to more than three classes of antibiotics, fulfilling the criterion for multidrug resistance. At an initial concentration of 9 log colony-forming units (CFU)/mL, the intestinal concentration of these four isolates crossed the threshold required to induce widespread diarrhea in the general population. Under rice slurry protection, all tested isolates maintained intestinal concentration beyond the threshold when the initial concentration was increased to &#x2265;8 log CFU/mL. Moreover, the upregulations of genes associated with acid tolerance, bile tolerance and stress response were observed in the surviving MDR B. cereus isolates. Digestion markedly altered the antibiotic resistance profiles of the MDR B. cereus isolates. In the absence of a food matrix, the MDR isolates lost their resistance to imipenem, meropenem, amoxicillin-clavulanic acid, and trimethoprim-sulfamethoxazole post-digestion and was influenced by the initial concentration of the strains. In the presence of food matrix rice slurry, the effects of digestion on the antibiotic resistance of MDR B. cereus isolates can be mitigated, enabling them to maintain their antibiotic resistance to the greatest extent. Most remarkably, after digestion, the isolates Bce055 and Bce166 exhibited newly emergent resistance to cefotetan and trimethoprim-sulfamethoxazole, respectively. Our findings clarify the fate of MDR B. cereus isolates in the gastrointestinal tract and inform the development of prevention and control strategies for foodborne diseases caused by this pathogen.

Drug Resistance, Multiple, Bacterial

Analysis and validation of abnormal signaling pathways and immune cell infiltration characteristics in digestive system cancers based on peroxisome-related genes.

BACKGROUND: Although emerging evidence suggests a role for peroxisomes in tumorigenesis, their functions in digestive cancers remain unclear. This study aims to investigate the association between peroxisomes and digestive tract tumors. METHODS: To systematically investigate peroxisomal functions in digestive cancers, we first constructed and validated tumor-specific prognostic signatures based on peroxisome-related genes (PRGs) through univariate Cox, least absolute shrinkage and selection operator (LASSO), and multivariate Cox regression analyses. We then characterized the tumor immune microenvironment (TIME) with CIBERSORT, X-CELL, and EPIC algorithms, and identified tumor-specific and common signalings via Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA). Focusing on hepatocellular carcinoma (HCC), we experimentally validated peroxisome-related therapeutic responses by profiling signature genes in radioresistant cells and an orthotopic transarterial chemoembolization (TACE) rat model. PEX13 knockdown further assessed peroxisomal role in radiosensitivity and targeted therapy response. Clinical relevance of PEX13 was evaluated in HCC cohort. Single-cell RNA sequencing dataset and lipidomics further revealed peroxisomal mechanisms in HCC progression. Finally, peroxisomal function in colorectal cancer (CRC) was validated in vitro. RESULTS: Novel peroxisome-related prognostic signatures demonstrated strong predictive power in HCC, colon adenocarcinoma, rectal adenocarcinoma, pancreatic adenocarcinoma, gastric adenocarcinoma, esophageal adenocarcinoma, esophageal squamous cell carcinoma, and cholangiocarcinoma. High-risk patients displayed an immunosuppressive microenvironment, characterized by increased infiltration of regulatory T cells, M2 macrophages, Th2 cells, or cancer-associated fibroblasts, or Th1 cells' reduction. Peroxisomes engaged in several distinct yet convergent pathways, most notably "positive regulation of response to stimuli". HCC prognostic genes were dynamically regulated in response to therapeutic stimuli, including radiotherapy, targeted therapy, and TACE. Clinically, the expression of PEX13 was markedly upregulated in tumor tissues from therapy-resistant HCC patients. Mechanistically, peroxisomal dysfunction induced by silencing PEX13 in HCC or UBE2D2 in CRC may overcome therapeutic resistance (radiotherapy/ lenvatinib resistance in HCC, radioresistance in CRC) through reprogramming lipid metabolism. CONCLUSIONS: Peroxisomes act as pivotal regulators of digestive cancer progression by modulating signaling pathways, the TIME, therapeutic resistance, and lipid metabolism. Targeting peroxisomal function, particularly in high-risk subgroups of HCC and CRC, warrants further exploration as a promising therapeutic strategy.

Peroxisomes

Host-virus dynamics in anaerobic digesters facing abiotic inhibition.

Viruses play a major role in controlling the structure and dynamics of microbial communities in anaerobic digesters, ecosystems sensitive to disturbances that inhibit methane production. Here, we studied the interplay between abiotic disturbances, microbiome and virome composition, and process performance, to assess whether provirus induction can be triggered by abiotic stresses known to inhibit anaerobic digestion (ammonium, phenol and sodium chloride). We monitored viral dynamics in batch mesophilic anaerobic digesters fed with biowaste through shotgun metavirome sequencing. The diversity of both prokaryotes and viruses was high, with Clostridiales dominating the prokaryotic community and Caudoviricetes dominating the viromes. We identified 132 viral contigs and 19 host genera that were differentially abundant under disturbed conditions. No significant impact of the tested abiotic stresses on provirus induction was observed under the current experimental and analytical framework. The results were consistent with viruses exerting steady, background-level predation through a putative combination of kill-the-winner dynamics at the sub-genus level and piggyback-the-winner dynamics, rather than stress-triggered, synchronous lytic bursts. A few auxiliary metabolic genes were detected, potentially targeting carbon, sulfur and cofactor metabolism in anaerobic digestion. Temperate viruses were dominant, representing up to 71% of the viral genomes confirmed as complete across all conditions. Electron microscopy analysis revealed diverse virus-like particles, including head-tailed particles typical of Caudoviricetes, but also spherical, rod-shaped and spindle-shaped particles typical of archaeal viruses. Notably, we present a new virus family, Eurekaviridae, of spindle-shaped viruses associated with methanogenic archaea.

Anaerobiosis

Digestive cancers: mechanisms, therapeutics and management.

Cancers of the digestive system are major contributors to global cancer-associated morbidity and mortality, accounting for 35% of annual cases of cancer deaths. The etiologies, molecular features, and therapeutic management of these cancer entities are highly heterogeneous and complex. Over the last decade, genomic and functional studies have provided unprecedented insights into the biology of digestive cancers, identifying genetic drivers of tumor progression and key interaction points of tumor cells with the immune system. This knowledge is continuously translated into novel treatment concepts and targets, which are dynamically reshaping the therapeutic landscape of these tumors. In this review, we provide a concise overview of the etiology and molecular pathology of the six most common cancers of the digestive system, including esophageal, gastric, biliary tract, pancreatic, hepatocellular, and colorectal cancers. We comprehensively describe the current stage-dependent pharmacological management of these malignancies, including chemo-, targeted, and immunotherapy. For each cancer entity, we provide an overview of recent therapeutic advancements and research progress. Finally, we describe how novel insights into tumor heterogeneity and immune evasion deepen our understanding of therapy resistance and provide an outlook on innovative therapeutic strategies that will shape the future management of digestive cancers, including CAR-T cell therapy, novel antibody-drug conjugates and targeted therapies.

Humans

Genome-resolved assessment of archaeal diversity in full-scale anaerobic digesters reveals variability in mcrA primer coverage.

AIMS: Methanogenic archaea are key players in anaerobic digestion, driving methane production in biogas reactors. This study aimed to assess the diversity of methanogenic archaea in full-scale anaerobic digesters using genome-resolved metagenomics and to systematically evaluate the taxonomic coverage of commonly used mcrA-targeted qPCR primer sets against this genomic framework. METHODS AND RESULTS: Methanogenic diversity was assessed using 113 dereplicated archaeal metagenome-assembled genomes (MAGs) recovered from 109 full-scale anaerobic digesters treating diverse substrates. Genome-resolved analyses revealed a diverse archaeal community spanning multiple phyla, dominated by Halobacteriota and Methanobacteriota, with additional representatives from Methanobacteriota_B, Thermoplasmatota, and Thermoproteota. The presence of the mcrA gene was identified in a subset 55 MAGs, which were subsequently used as the genomic framework to evaluate six commonly used mcrA qPCR primer sets in silico. This subset clustered into nine phylogenetic groups and formed the basis for the primer coverage analysis. The evaluation revealed marked differences in taxonomic coverage among primer sets. Most primers preferentially detected Methanobacteriales and Methanosarcinales, while underrepresenting or excluding other methanogenic lineages, including H&#x2082;-dependent methylotrophic Methanomassiliicoccaceae. CONCLUSIONS: Commonly used mcrA primer sets differ substantially in their ability to capture methanogenic diversity, with some showing broad representation of reactor-associated methanogens and others exhibiting strong lineage-specific biases. Genome-resolved metagenomics provides an effective framework for benchmarking primer performance and supports the selection and improvement of molecular tools for more accurate monitoring of anaerobic digestion systems.

Archaea

Optimizing a culture-enriched hybrid metagenomics pipeline to assess the AMR footprint of livestock manure in anaerobic digestate.

The role of environmental samples from livestock production systems, including manure and anaerobic digestate, as reservoirs of antimicrobial resistance genes (ARGs) is likely underestimated because conventional metagenomic approaches can overlook low-abundance ARGs and often lack the resolution to associate these genes with their microbial hosts and co-localized mobile genetic elements (MGEs). We evaluated whether culture-enriched metagenomics (CEMG), with and without antibiotic selection, enhances ARG detection in anaerobic digestate and improves the resolution of ARG-MGE-host associations using hybrid short- and long-read metagenomic assembly. CEMG increased ARG recovery; mean ARG abundance rose from 15.4 counts per million (CPM) in metagenomic fresh digestate (FD) to 124 CPM in CEMG without antibiotics and 160 CPM in antibiotic-selective CEMG. In FD, only 9 unique ARGs were detected, whereas CEMG recovered 112, including ARGs of clinical importance, such as glycopeptide resistance, beta-lactamase genes, and the cfr 23S rRNA methyltransferase conferring cross-resistance to multiple antibiotic classes. Antibiotic selection induced targeted, class-specific shifts in ARG profiles, with ARGs associated with tetracycline resistance consistently enriched across treatments. Hybrid metagenomic assembly resolved the genomic context of 784 ARGs, of which 59.3% were co-localized with at least one class of MGEs, predominantly plasmids and integrative conjugative elements/integrative mobilizable elements. Biocide and metal resistance genes frequently co-occurred with ARGs on the same contigs. Together, these findings demonstrate that antibiotic-selective culture enrichment enhances resistome surveillance by improving detection of low-abundance ARGs, while hybrid assembly provides critical genomic context for assessing their mobility and host associations.IMPORTANCELivestock manure and its byproducts, such as anaerobic digestate, are recognized as important environmental reservoirs of antimicrobial resistance genes (ARGs) and resistant bacteria, yet current metagenomic approaches may underestimate this risk by failing to detect low-abundance but clinically relevant ARGs. Here, we show that integrating culture enrichment with hybrid metagenomics improves ARG recovery and reveals ARG co-localization with mobile genetic elements and putative bacterial hosts. This approach captures a cultivable and condition-responsive fraction of the resistome that is not readily accessible through direct metagenomic sequencing alone, providing a more informative framework for environmental AMR surveillance.

anaerobic digestion

Metagenomic insights into the mechanisms of heteroatom-doped, iron-loaded biochar in enhancing anaerobic digestion of waste activated sludge.

Anaerobic digestion is a crucial technology for resource recovery from waste activated sludge. Enhancing its methane production efficiency using conductive materials is a key research objective. This study aimed to elucidate the mechanisms by which conductive materials promote this process. Three types of biochar(FeS@BC300, FeP@BC600, and FeP@BC900) were prepared by doping bamboo powder with N, P, S and iron salts under pyrolysis conditions at 300-900&#xa0;&#xb0;C, and their physical and chemical properties were characterized, including surface functional groups, specific surface area, capacitance, electrical resistance, electron-accepting capacity (EAC), and electron-donating capacity (EDC). These analyses assessed the influence of synthesis parameters. These materials were subsequently introduced into the anaerobic digestion of thermally hydrolyzed sludge to evaluate their impacts on methanogenic performance, microbial community structure, and metabolic pathways. The results show that the FeP@BC600 material, which exhibited the highest EDC, substantially increased microbial cytochrome c production (by 29.2&#xa0;% compared to the control). This enhancement improved interspecies electron transfer, stimulated ATP synthesis (increased by 41.5&#xa0;%), and reinforced both hydrogenotrophic and acetoclastic methanogenic pathways, ultimately elevating methane production by 55&#xa0;%. Integrated analysis of metagenomic data, material properties, and performance metrics revealed that the key mechanism by which FeP@BC600 promotes methanogenesis is through the enrichment of cytochrome c-encoding genes, thereby facilitating direct interspecies electron transfer (DIET) and augmenting ATP synthesis. This study provides a foundation for the subsequent application of conductive materials to enhance anaerobic digestion and offers guidance for the optimized design of such materials.

Sewage

Comparative transcriptomics of Venus flytrap (Dionaea muscipula) across stages of prey capture and digestion.

The Venus flytrap, Dionaea muscipula, is perhaps the world's best-known botanical carnivore. The act of prey capture and digestion along with its rapidly closing, charismatic traps make this species a compelling model for studying the evolution and fundamental biology of carnivorous plants. There is a growing body of research on the genome, transcriptome, and digestome of Dionaea muscipula, but surprisingly limited information on changes in trap transcript abundance over time since feeding. Here we present the results of a comparative transcriptomics project exploring the transcriptomic changes across seven timepoints in a 72-hour time series of prey digestion and three timepoints directly comparing triggered traps with and without prey items. We document a dynamic response to prey capture including changes in abundance of transcripts with Gene Ontology (GO) annotations related to digestion and nutrient uptake. Comparisons of traps with and without prey documented 174 significantly differentially expressed genes at 1 hour after triggering and 151 genes with significantly different abundances at 24 hours. Approximately 50% of annotated protein-coding genes in Venus flytrap genome exhibit change (10041 of 21135) in transcript abundance following prey capture. Whereas peak abundance for most of these genes was observed within 3 hours, an expression cluster of 3009 genes exhibited continuously increasing abundance over the 72-hour sampling period, and transcript for these genes with GO annotation terms including both catabolism and nutrient transport may continue to accumulate beyond 72 hours.

Droseraceae

Evaluation and Optimization of Different Digestion Strategies for In-Depth Proteomic Characterization of Residual Host Cell Proteins in rAAV-Based Gene Therapy Products.

Recombinant adeno-associated virus vectors (rAAVs) are the most important vectors for in vivo gene therapies, yet their safety relies on low levels of residual host cell proteins (HCPs). While mass spectrometry-based proteomics enables sensitive and untargeted HCP profiling, it faces challenges with matrix interferences from purification buffers and the high dynamic range between abundant viral capsids and trace HCPs. Although sample preparation methods that address these challenges are well-established for antibody products, their adaptation to rAAV purification stages and products remains largely unexplored. In this study, we systematically evaluated three widely used proteomic sample preparation workflows&#x2500;In-Solution, FASP, and SP3&#x2500;across different stages of rAAV purification. In addition, each workflow was tested under both standard denatured digestion conditions and a "native" digestion strategy designed to reduce dynamic range by preserving capsid integrity while selectively digesting HCPs. This comparison identified the native FASP protocol as the most effective sample preparation method for overcoming matrix interference and dynamic range challenges, consistently outperforming other workflows in HCP identification across purification stages. Further optimization of the native FASP workflow enhanced its performance, achieving the highest host cell (HC) proteome depth, particularly in highly purified drug substance samples. This optimized sample preparation strategy provides a robust and easy-to-use framework for deep characterization of the host cell proteome in rAAV samples. By enabling deeper insights into the HCP profile, this approach supports improved understanding of the rAAV purification process and facilitates the development of targeted strategies to enhance product quality and safety.

Dependovirus

A Robust, Self-Digestion-Resistant LysN with Superior Activity and Cleavage Fidelity for Advanced Proteomic Workflows.

LysN is a valuable protease in proteomics because it cleaves peptide bonds N-terminal to lysine, generating peptides with physicochemical properties complementary to those produced by LysC and trypsin. However, the broader adoption of LysN in proteomic workflows has been limited by the lack of commercially available enzymes that combine high activity, low missed-cleavage rates, and sufficient stability under practical sample-processing conditions. Here, we report the recombinant production and proteomic characterization of a self-digestion-resistant and highly active LysN from Shewanella loihica (SL-LysN). Using terminomics, we mapped the mature N- and C-termini of the enzyme and established the primary structure of the active protease. We further developed a high-density fermentation, refolding, and purification workflow to obtain highly purified recombinant SL-LysN. Biochemical and proteomic benchmarking showed that SL-LysN displayed 3.3-fold higher specific activity than commercial LysN and reduced missed cleavages by approximately 80%. Notably, SL-LysN retained high activity in the presence of 8 M urea or 1% SDS and showed strong resistance to autolysis, indicating exceptional robustness for proteomic sample preparation. In complex mammalian proteome digests, SL-LysN achieved >95% cleavage specificity and a missed-cleavage rate of only 5.9%. These features address a long-standing bottleneck in N-terminal proteolysis and establish SL-LysN as a high-performance enzymatic tool for advanced proteomic workflows, including deep protein sequencing, quantitative proteomics, terminomics, de novo sequencing and analyses requiring efficient digestion under denaturing conditions.

Shewanella

Metagenome reveals the possible mechanism that microbial strains promote methanogenesis during anaerobic digestion of food waste.

For better understanding the mechanism of microbial strains promoting methane production, four strains Hungatella xylanolytica A5, Bacillus licheniformis B1, Paraclostridium benzoelyticum C2 and Advenella faeciporci E1 were inoculated into anaerobic digestion systems. After bioaugmentation, the cumulative methane production of A5, B1, C2 and E1 groups elevated by 11.68%, 8.20%, 18.21% and 15.67% compared to CK group, respectively. The metagenomic analysis revealed that the species diversity and uniformity of the experimental groups was improved, and hydrolytic acidifying bacteria, represented by Clostridiaceae, Anaerolineaceae and Oscillospiraceae, and methanogens, such as Methanotrichaceae and Methanobacteriaceae, were enriched. Meanwhile, the abundance of key genes in carbohydrate, pyruvate and methane metabolism was increased in the inoculated groups, providing reasonable reasons for more methane production. The strengthening mechanism of microbial strains in this study offered a theoretical foundation for selecting a suitable bioaugmentation strategy to solve the problems of slow start-up and low methane production in anaerobic digestion.

Methane

[Intestinal microbiota alterations after digestive tract reconstruction surgery and their impacts on host physiology].

The gut microbiota, acknowledged as the human body's 'second genome', plays a pivotal role in maintaining health. Digestive tract reconstruction surgery profoundly alters the anatomical structure and physiological environment of the gastrointestinal tract, thereby inducing significant shifts in the intestinal microbiota. These microbial changes subsequently influence host physiological functions through metabolic, immune, neuroendocrine, and other pathways. For instance, Roux-en-Y gastric bypass surgery enriches short-chain fatty acid(SCFA)-producing Bacteroides, improving systemic insulin sensitivity. Conversely, pancreaticoduodenectomy leads to a marked enrichment of potential pathobionts such as Klebsiella and Clostridium, which may elevate the risk of infections and tumor recurrence. This review comprehensively summarizes the characteristic changes in the gut microbiota following various digestive tract reconstruction procedures and discusses their multifaceted impacts on host physiology, aiming to provide insights for future experimental research and clinical practice.

Humans