Extracellular vesicles (EVs) are nanometer-sized lipid structures actively secreted by Gram-negative and Gram-positive bacteria, representing a sophisticated microbial adaptation and communication strategy. These structures are involved in biomolecular transport, the regulation of biological processes, the modulation of host–pathogen interactions, and adaptation to hostile environmental conditions. EVs also play a crucial role in virulence, antibiotic resistance, and biofilm formation. This review will explore the biogenesis, composition, and biological mechanisms of outer membrane vesicles (OMVs) secreted by Gram-negative bacteria and membrane vesicles (MVs) generated by Gram-positive bacteria. In detail, the modulation of EVs in response to antibiotic exposure will be addressed. The role of EV morpho-functional adaptations will be studied in antimicrobial resistance, the gene determinant spread, and survival in adverse environments. This study aims to provide a comprehensive overview of the EV role in bacterial physiology, highlighting their ecological, evolutionary, and biotechnological implications. An overview of the enzymes and proteins mainly involved in OMV-mediated resistance mechanisms will also be provided. These insights could open new perspectives for developing therapeutic strategies that counteract EV secretion and biotechnological applications, such as vaccines and drug delivery systems.

A thermo-acidophilic bacterium, Alicyclobacillus mali FL18, was isolated from a hot spring of Pisciarelli, near Naples, Italy; following genome analysis, a novel putative β-xylosidase, AmβXyl, belonging to the glycosyl hydrolase (GH) family 3 was identified. A synthetic gene was produced, cloned in pET-30a(+), and expressed in Escherichia coli BL21 (DE3) RIL. The purified recombinant protein, which showed a dimeric structure, had optimal catalytic activity at 80 °C and pH 5.6, exhibiting 60% of its activity after 2 h at 50 °C and displaying high stability (more than 80%) at pH 5.0–8.0 after 16 h. AmβXyl is mainly active on both para-nitrophenyl-β-D-xylopyranoside (K_M 0.52 mM, k_cat 1606 s⁻¹, and k_cat/K_M 3088.46 mM⁻¹·s⁻¹) and para-nitrophenyl-α-L-arabinofuranoside (K_M 10.56 mM, k_cat 2395.8 s⁻¹, and k_cat/K_M 226.87 mM⁻¹·s⁻¹). Thin-layer chromatography showed its ability to convert xylooligomers (xylobiose and xylotriose) into xylose, confirming that AmβXyl is a true β-xylosidase. Furthermore, no inhibitory effect on enzymatic activity by metal ions, detergents, or EDTA was observed except for 5 mM Cu²⁺. AmβXyl showed an excellent tolerance to organic solvents; in particular, the enzyme increased its activity at high concentrations (30%) of organic solvents such as ethanol, methanol, and DMSO. Lastly, the enzyme showed not only a good tolerance to inhibition by xylose, arabinose, and glucose, but was activated by 0.75 M xylose and up to 1.5 M by both arabinose and glucose. The high tolerance to organic solvents and monosaccharides together with other characteristics reported above suggests that AmβXyl may have several applications in many industrial fields.

Micro- and nanoplastics (MPs/NPs) have emerged as pervasive environmental contaminants with increasing implications for human health, particularly within the digestive system. This review critically examines the role of MPs/NPs as disruptors of gastrointestinal and liver homeostasis through the lens of the plastic–gut–liver axis. We synthesize current evidence on primary exposure routes—including ingestion, inhalation, dermal contact, and transplacental transfer—and highlight their intestinal uptake, systemic dissemination, and tissue accumulation. Mechanistically, MPs/NPs compromise intestinal barrier integrity, promote oxidative stress, and induce microbiota dysbiosis, facilitating the translocation of microbial-derived signals to the liver via the portal circulation. This process triggers inflammatory signaling cascades, metabolic reprogramming, and immune dysregulation, contributing to hepatic steatosis, insulin resistance, and potential carcinogenic processes. Emerging evidence also implicates pancreatic dysfunction and β-cell stress within a broader gut–liver axis context. We further discuss the systemic propagation of MPs/NPs-induced dysbiosis along multi-organ axes, including gut–lung and gut–brain interactions. Despite robust preclinical data, human evidence remains limited due to methodological heterogeneity and the lack of standardized biomarkers. This review underscores critical knowledge gaps and emphasizes the need for integrative, translational approaches to clarify long-term health risks and inform regulatory strategies within the environmental exposome framework.

Agri-food waste represents a rich source of bioactive compounds with potential applications in the food, pharmaceutical, and cosmetic industries. This study investigates sustainable strategies for extracting bioactive compounds, with a specific focus on enzyme-assisted extraction (EAE) as an alternative to conventional chemical methods. Spent coffee grounds (SCGs), sunflower residues, and citrus residues were analyzed. Key parameters, including total phenolic content, antioxidant capacity, reducing sugar content, antimicrobial effects, and antiproliferative activity on human cells, were evaluated. SCG and sunflower extracts demonstrated the highest antioxidant content, albeit with minimal variations between enzyme treatments. Notably, enzyme-treated citrus extracts exhibited increased reducing sugar content, significant antimicrobial activity, and inhibition of microbial biofilms. Moreover, citrus extracts were non-toxic to healthy cells while showing pronounced effects against metastatic melanoma cells. These findings underscore the potential of citrus waste as a valuable source of bioactive compounds and highlight EAE as an effective and sustainable extraction technique.

Background: Medical device-associated infections represent a major component of healthcare-associated infections. Biofilm formation promotes microbial persistence on device surfaces, reduces antimicrobial susceptibility, and contributes to multidrug resistance (MDR), complicating diagnosis and treatment. Materials and Method: This study investigated biofilm production and antimicrobial resistance in microorganisms recovered from 100 indwelling and implantable medical devices, including urinary and venous catheters, urethral stents, catheter tips, and orthopedic or prosthetic materials, collected at a tertiary-care hospital (AOU “San Giovanni di Dio e Ruggi d’Aragona”, Salerno, Italy). Microbiological cultures were performed using direct and enrichment methods. Microbial identification was carried out by MALDI-TOF MS, antimicrobial susceptibility testing by VITEK^® (bioMérieux, Marcy-l'Étoile, France) 2 according to EUCAST criteria, and biofilm production was assessed using the crystal violet tissue culture plate assay. MDR status was defined according to international guidelines. Results: Microbial growth was detected in the majority of analized devices, frequently with polymicrobial contamination. Within the study cohort, coagulase-negative staphylococci (CoNS) were the most frequently recovered microorganisms (20%), followed by Klebsiella pneumoniae (10%), Candida albicans (9%), Staphylococcus aureus (9%), Enterococcus faecalis (8%), and Escherichia coli (8%). A significant association was observed between multidrug resistance and biofilm production, with MDR isolates showing a markedly higher likelihood of being biofilm producers compared with non-MDR isolates (OR 9.50; 95% CI 2.72–42.96; p < 0.005). Biofilm formation also differed significantly among device types (p = 0.028). Conclusions: These findings indicate a high prevalence of biofilm-producing MDR microorganisms among isolated recovered from medical devices in our cohort and highlight a significant association between MDR phenotype and biofilm production. These results provide a microbiological characterization of device-associated isolates that may support future studies on infection dynamics and control strategies.

Nanomaterials are emerging as promising alternatives to conventional antibiotics in the fight against a wide variety of pathogenic bacterial species. Among metal-based nanomaterials, silver nanoparticles (AgNPs) are of particular interest because of their broad-spectrum antimicrobial activity and potential applications in the biomedical field. Biologically synthesized AgNPs (Bio-AgNPs) can be produced using plant extracts, bacteria and fungi. These approaches are eco-friendly, cost-effective, and associated with low cytotoxicity. This review provides an up-to-date summary of the recent literature, presenting a comprehensive overview of the biological synthesis of AgNPs, with particular emphasis on bacterial and fungal derivatives. This green synthesis typically follows intracellular or extracellular pathways, in which enzymes, proteins, and metabolites mediate the reduction of silver ions and stabilization of nanoparticles (NPs). Physicochemical parameters, such as pH, temperature, and precursor concentration, and various features of Gram-positive and Gram-negative bacteria strongly influence NPs’ attributes, including size, morphology, and functional properties. In addition, culture supernatants and media components may drive NPs formation, supporting the feasibility of cell-free (CF) biosynthesis of NPs. We also summarize the principal antimicrobial mechanisms proposed for AgNPs and place these findings in a broader context by considering other metal NPs (Au, Ti, Zn, and Cu). Despite substantial recent progress and growing interest in NPs, major challenges remain, including mechanistic understanding, limited reproducibility, and difficulty in scaling up production. Overall, microorganisms and their CF derivatives represent a sustainable and versatile platform for developing functional nanomaterials, such as AgNPs, with significant potential for antimicrobial applications even in combating antimicrobial resistance (AMR).