AIMS Microbiology最新文献

While plant food is an obligate part of human nutrition, vegetables and fruits are often contaminated by adherent foodborne pathogens, in turn requiring biocompatible solutions for their efficient elimination. We report the effect of proteinase (subtilisin) and nuclease (DNAse) additions to the dishwashing liquid for a more efficient removal of adherent bacteria and biofilms from glass surfaces and vegetables. The 15 min treatment with solely 0.06% protease solution decreased preformed biofilms of S. aureus and S. Typhimurium threefold, and treatment with 0.25% nuclease reduced them twofold, respectively. While nuclease itself was of low efficiency, the protease-nuclease mixture (0.06% of each protein) reduced the biomasses of biofilms of these bacteria fourfold, as well as biofilms of E. faecalis, E. coli, and K. pneumoniae twofold. The addition of enzymes to the dishwashing liquid increased the removal of Gram-negative bacteria from the glass 5-10-fold compared to basic liquid. Furthermore, enzymes enhanced the removal of adherent bacteria from lettuce, cucumber, celery, and apple up to 100-fold for S. aureus and E. faecalis and 20-fold for Gram-negative species, respectively, compared to the basic dishwashing liquid, as indicated by CFUs count and qPCR data. These data suggest that protease, both individually and especially in mixture with nuclease, is an attractive additive to dishwashing liquids to provide the removal of up to 99% of adherent bacteria from dishes, fruits, and vegetables.

SeqA is a key regulator of DNA replication initiation and chromosome cohesion in Escherichia coli. Loss of SeqA causes replication asynchrony, segregation defects, and growth delay, but its role in antibiotic susceptibility has remained unclear. Fluoroquinolones (FQs), which directly target bacterial DNA gyrase and topoisomerase IV to generate double-strand breaks (DSBs), provide a useful system to probe how chromosomal organization influences antibiotic response. In this study, we investigated whether SeqA loss alters sensitivity to FQs compared to antibiotics with non-DNA targets. MIC and MBC assays revealed that ΔseqA cells exhibit a specific low-level resistance to FQs, with ~1.5-fold higher inhibitory and bactericidal thresholds while retaining wildtype sensitivity to β-lactams and aminoglycosides. Using MuGam-GFP and RecA-GFP reporters, we showed that ΔseqA cells had fewer DSBs and mount an attenuated SOS response at wildtype MIC levels, enabling survival at otherwise lethal doses. Complementation restored wildtype sensitivity, confirming SeqA's direct involvement. Importantly, resistance was abolished in ΔseqA-rpoS double mutants and upon sub-MIC rifampicin treatment, demonstrating that RpoS-dependent transcriptional reprogramming underlies this phenotype. This suggested that ΔseqA strains acquire resistance through an RpoS-dependent regulatory effect that likely involves broad transcriptional reprogramming that underlies this phenotype. Together, these results showed that loss of SeqA alters chromosome organization in a way that lowers fluoroquinolone-induced DNA damage and enables RpoS-dependent low-level resistance.

Soil, the Earth's upper crust layer, is crucial for ecological processes, comprising mineral, organic, and biological components that determine fertility and multifuncionality. Human-induced degradation necessitates advancements in pedology and soil conservation. The rhizosphere, surrounding plant roots, houses a diverse microbial community, notably bacteria, which enhance plant growth and disease resistance. Root exudates fuel biological activity and nutrient cycling, supporting microbial growth, improving soil structure, and reducing plant stress. Plant-microorganism interactions in ecological and agricultural systems play a vital role for maintaining primary production and ecosystem sustainability. Moreover, arbuscular mycorrhizae and nitrogen-fixing bacteria are essential, influencing plant development, sustainability, and ecosystem health. Specific bacterial phyla populate the rhizosphere and endosphere, with Plant Growth-Promoting Rhizobacteria (PGPR), such as Pseudomonas spp. and Bacillus spp., playing a prominent role. PGPR employ direct and indirect mechanisms, including phytohormone production, mineral solubilization, systemic resistance induction, antibiosis, competition for resources, and ACC deaminase activity, The amalgamation of these traits underscores the conceptual foundation for comprehending the ecological and agricultural implications of employing microbes. This inquiry is particularly relevant to sustainable agriculture, where the use of microbes, including PGPR, plays a crucial role in biofertilization and mitigating environmental stressors. Thus, investigating the ecological and agricultural implications through multi-omics approaches such as genomics, transcriptomics, proteomics, and metabolomics offers valuable insights. The integration of these multi-omics data provides a comprehensive framework for understanding the complex interactions between plants, bacteria, and fungi. This holistic perspective not only deepens our understanding of soil ecology but also lays the groundwork for informed and sustainable agricultural practices, fostering resilience against environmental stresses.

Antimicrobial resistance (AMR) is a significant global health challenge that threatens the effectiveness of antibiotics and other antimicrobial agents. Here, we examined the molecular mechanisms that contribute to bacterial resistance, including alterations at target sites, enzymatic inactivation, efflux pump overexpression, and biofilm formation. Key resistance determinants, such as bla _CTX-M-15, bla _NDM-1, mecA, and erm genes, mediate enzymatic degradation and target modification, thereby diminishing antibiotic potency. Clinically significant pathogens, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecium, exemplify a broad spectrum of resistance and frequently acquire these traits through horizontal gene transfer (HGT), facilitated by plasmids, integrons, and transposons. The propensity for biofilm formation further augments bacterial persistence by impeding antimicrobial penetration and fostering intra-community genetic exchanges. The clinical ramifications of AMR are profound, contributing to elevated morbidity and mortality, extended hospitalization, and increased rates of therapeutic failure, all of which exert significant strain on the healthcare system. The economic consequences are equally severe, with escalating healthcare expenditures and substantial projected losses to the global gross domestic product (GDP). Addressing these challenges necessitates the adoption of advanced approaches, including genomic surveillance, antimicrobial stewardship, novel inhibitors targeting resistance pathways, immuno-antibiotics, and bacteriophage therapy. This review underscores the need to integrate molecular diagnostics and a One Health perspective to monitor and contain resistance across human, animal, and environmental reservoirs. A comprehensive understanding of the molecular and epidemiological aspects of AMR is essential for driving advancements in diagnostics, therapeutics, and policies, thereby ensuring global health protection.

Autophagy is a critical host defense mechanism against pathogens; however, enterohemorrhagic Escherichia coli (EHEC) O157:H7 exploits it to establish infection. Here, we revealed how EHEC's effector EspF collaborates with host Annexin A6 (ANXA6) to suppress autophagy and drive inflammation. Our results showed that CRISPR/Cas9-mediated anxa6 knockout in intestinal epithelial cells reversed EHEC-induced autophagic inhibition, as evidenced by elevated LC3B-II levels and reduced p62 accumulation. Mechanistically, EspF stabilizes ANXA6 to disrupt PI3K/mTOR signaling and impair autophagosome formation, whereas ANXA6 suppresses the expression of ATG16L1, a key autophagy regulator. In this study, EHEC infection triggered IL-1β hypersecretion in macrophages, which was coupled with NF-κB pathway hyperactivation via IκBα/p65 phosphorylation. In vivo, EHEC infection regulated intestinal ANXA6 expression, correlating with mucosal inflammation and barrier dysfunction. Crucially, ANXA6/ATG16L1 axis disruption created a self-reinforcing cycle of impaired autophagy, bacterial persistence, and inflammatory escalation. Our findings identified ANXA6 as a context-dependent autophagy modulator and ATG16L1 as a novel EHEC target, providing mechanistic insights into EHEC pathogenesis.

The development of innovative feed resources for livestock is crucial for ensuring nutrient adequacy while reducing greenhouse gas emissions. We aimed to evaluate the effects of Moringa oleifera leaf extract (ML) supplementation on in vitro nutrient degradability, net gas production (GP), ruminal fermentation, methane (CH₄) emissions, and methanogen community structure using a semi-automated in vitro gas production system. Methanogen-specific 16S rRNA genes were amplified through nested PCR and then sequenced with Sanger sequencing. Microbial analyses were conducted using 16S rRNA sequencing. A basal diet (50% concentrate and 50% forage) was incubated in vitro for 24 h as a control (no additives) and compared to diets supplemented with ML at 1.0, 2.0, and 3.0 mL/100 g dry matter (DM), designated ML1, ML2, and ML3, respectively. GC-MS profiling of ML revealed that glycerin (82.08%), unsaturated fatty acid derivatives such as linoleic acid, and minor bioactive sulfur- and nitrogen-containing compounds (e.g., L-cystathionine, homocysteine derivatives) were the major constituents. These compounds exert antimicrobial, membrane-disrupting, and redox-modulating effects, which provide the basis for the proposed mechanisms by which ML influences rumen fermentation and methanogenesis. Supplementation with ML significantly reduced net GP (linear, P < 0.001; quadratic, P = 0.002) and CH₄ production (linear, P = 0.033) across all levels. Similarly, truly degradable dry matter (TDDM; linear, P = 0.038) and truly degradable organic matter (TDOM; linear, P = 0.016) decreased, whereas the partitioning factor increased with ML1 and ML2 supplementation (quadratic, P = 0.002). Ruminal pH and ammonia nitrogen (NH₃-N) concentrations remained unaffected. However, ML treatments reduced total volatile fatty acids (linear, P = 0.009; quadratic, P = 0.003) and butyrate concentrations (linear, P < 0.001). Acetate and propionate concentrations were reduced by ML1 and ML2 (quadratic, P = 0.005). In contrast, ML3 increased isobutyrate (linear, P = 0.004; quadratic, P = 0.012) and isovalerate (linear, P = 0.023; quadratic, P = 0.012) levels. Protozoal enumeration showed that Diplodinium spp. counts decreased with ML (linear, P = 0.008), while Epidinium spp. counts were reduced by ML1 (quadratic, P = 0.048). Phylogenetic analysis of 16S rRNA gene sequences indicated that ML supplementation altered the rumen methanogen community, with distinct shifts toward Methanobrevibacter smithii and M. woesei in ML2 and ML3, respectively. These findings suggest that ML selectively inhibits methanogenic archaea, potentially contributing to reduced CH₄ emissions and altered fermentation profiles.

Synthetic biology has revolutionized precision medicine by enabling the development of engineered bacteria as living therapeutics, dynamic biological systems capable of sensing, responding to, and functioning within complex physiological environments. These microbial platforms offer unprecedented adaptability, allowing for real-time detection of disease signals and targeted therapeutic delivery. This review explores recent innovations in microbial engineering across medical, industrial, environmental, and agricultural domains. Key advances include CRISPR-Cas systems, synthetic gene circuits, and modular plasmid architectures that provide fine-tuned control over microbial behavior and therapeutic output. The integration of computational modeling and machine learning has further accelerated design, optimization, and scalability. Despite these breakthroughs, challenges persist in maintaining genetic stability, ensuring biosafety, and achieving reproducibility in clinical and industrial settings. Ethical and regulatory frameworks are evolving to address dual-use concerns, public perception, and global policy disparities. Looking forward, the convergence of synthetic biology with nanotechnology, materials science, and personalized medicine is paving the way for intelligent, responsive, and sustainable solutions to global health and environmental challenges. Engineered bacteria are poised to become transformative tools not only in disease treatment but also in diagnostics, biomanufacturing, pollution mitigation, and sustainable agriculture.

In this study, we provided the first comprehensive assessment of prokaryotic viability and respiratory activity across a 75°N transect in the Greenland Sea. Seawater samples collected during the CASSANDRA cruise (early September 2021, Italian Arctic Research Program PRA) were analyzed using LIVE/DEAD BacLight viability staining (L/D) and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) methods to quantify viable and metabolically active cells, respectively. Total prokaryotic abundance ranged between 0.13 and 8.8 × 10⁵ cells mL^-1, with metabolically active (CTC+) cells accounting for 0.1-12% of the total. Viable cells accounted for 7-48% of the bacterial community, showing a significant vertical variability that increased with depth (Coefficient of variability 44%), particularly in deeper, nutrient-rich water masses such as the Greenland Sea Deep Water and the Greenland Sea Arctic Intermediate Water, occupying the deep layer (below 2500 m depth) and the intermediate layer (500-2500 m depth), respectively. Significant correlations were found between microbial parameters and environmental variables associated with different water masses, notably nutrients (nitrates and phosphates), whereas temperature showed a more complex, indirect influence. These findings highlight that the prokaryotic community inhabiting the examined transect is well adapted to this extreme marine environment, emphasizing the complex interactions of multiple environmental factors in shaping microbial community structure and activity under low-temperature conditions.

The consumption of drinking water from sources other than tap water, such as bottled water or water dispenser (WD) machines, is increasing worldwide, driven by consumer preferences for health, convenience, and taste. This trend raises concerns about potential microbial contamination and associated public health risks. In this review, we aimed to comprehensively analyze the scientific literature on microbial contamination in water dispenser machines, evaluate the quality of dispensed water, identify sources of contamination and potential health implications, and propose solutions to mitigate these risks. We conducted a comprehensive search of scientific databases, including PubMed, EBSCO, and Google Scholar, using relevant keywords related to water dispenser contamination. Abstracts and methods of identified studies were critically appraised to ensure rigorous assessment of microbial contamination. Our analysis of approximately 70 studies revealed that despite consumer perceptions of health benefits, water dispenser machines can harbor higher levels of microbial contamination than the tap water sources supplying them. This review underscores the potential public health risks associated with water dispenser use, and highlights the need for increased vigilance, regular maintenance, and further research to ensure the safety of dispensed water.