Journal of microbiology and biotechnology最新文献

Dry eye disease (DED) is a multifactorial ocular disorder characterized by tear film instability, inflammation, and ocular surface damage. Although various therapeutic approaches are available, there remains a strong need for safer and more effective agents with clearly defined mechanisms of action. This study examined the protective effects of Misgurnus mizolepis protein hydrolysate (MMH) in both in vitro and in vivo models of DED. In vitro, pretreatment of air-dried human corneal epithelial cells with MMH attenuated oxidative stress and apoptosis. In vivo, oral administration of MMH to rats with atropine-induced DED restored tear secretion, preserved ocular tissue architecture, reduced immune cell infiltration, and downregulated inflammatory mediators in the cornea. Furthermore, MMH maintained tight junction proteins, suppressed pro-apoptotic signaling in the lacrimal gland, improved meibomian gland and goblet cell integrity, and mitigated neovascularization. Collectively, MMH demonstrated anti-inflammatory, anti-apoptotic, and tissue-protective effects, supporting its potential as a novel therapeutic candidate for DED.

Probiotics play a crucial role in promoting host health by modulating the composition of the gut microbiota through the production of their own bioactive metabolites. The aim of the study was to investigate the anti-atrophic effects of Lacticaseibacillus paracasei EFEL6501 (EFEL6501) in dexamethasone (DEX)-treated C2C12 myotubes and a mouse model. In vitro experiments demonstrated that specific bioactive metabolites present in the cell culture supernatant (CS) and lysate supernatant (LS) of EFEL6501 alleviated muscle degradation and restored muscle protein synthesis in DEX-induced C2C12 myotubes. Similarly, EFEL6501 supplementation in mice significantly enhanced muscle thickness (6.09 mm), grip strength (117.87 g), and the cross-sectional area (CSA) (34.11 μm²) of the gastrocnemius muscle, compared to the DEX group (5.70 mm, 106.87 g and 29.79 μm², respectively), by suppressing protein degradation pathways and improving muscle differentiation. Furthermore, EFEL6501 positively modulated the gut microbiota composition by increasing the abundance of beneficial bacteria, including Lactobacillus reuteri (7.19%), Bifidobacterium choerinum (25.66%), Bacteroides uniformis (0.29%), Allobaculum (0.63%), and Faecalibaculum (18.00%) compared to the DEX group (3.44%, 0.75%, 0.14%, -0.63%, and 8.53%, respectively), while also elevating acetate concentrations from 1.57 ± 0.27 mM to 1.97 ± 0.16 mM. Taken together, EFEL6501 may serve as a potential functional probiotic for preventing muscle atrophy by regulating muscle metabolism and gut microbiota composition.

Vancomycin-resistant Enterococcus (VRE) has demonstrated increasing global prevalence in recent years. Clinical detection currently relies on phenotypic methods including agar screening, minimum inhibitory concentration (MIC) testing, Kirby-Bauer disk diffusion, and Etest. In addition, molecular approaches such as polymerase chain reaction (PCR) and quantitative PCR (qPCR) can be applied for VRE identification. Nevertheless, these methods cannot achieve point-of-care detection (POCT). Thus, novel rapid diagnostic platforms have become urgently needed for curbing VRE transmission and containing nosocomial outbreaks. Recombinase polymerase amplification (RPA) and lateral flow strips (LFS) are effective tools for achieving rapid POCT. In this study, RPA was combined with LFS to establish a fast, sensitive, and specific detection method. This study established a multiplex RPA-LFS (mRPA-LFS) that delivers results within 30-40 min, with detection limits of 10² copies/μl for vanA, vanB, and vanM. Notably, the assay demonstrated high specificity without cross-reactivity to common bacterial/fungal pathogens, and showed 100% concordance with conventional PCR in 30 clinical samples. In this study, a rapid detection assay for vanA, vanB, and vanM genes in VRE was developed using mRPA-LFS technology. Characterized by high sensitivity, specificity, operational simplicity, and cost-effectiveness, this method is suitable for on-site detection.

L-Asparaginase is a potential therapeutic enzyme used in the treatment of acute lymphoblastic leukemia. It is also useful as a food processing aid. Hence, many studies have been conducted to develop and optimize production methods for L-asparaginase using various microbial hosts. In this study, a secretory expression route for L-asparaginase was developed using recombinant Corynebacterium glutamicum. Fourteen signal sequences were primarily mined and used to induce the secretion of Escherichia coli L-asparaginase II (AsnB) in C. glutamicum. The signal sequence ss2629 induced efficient secretion of AsnB, achieving a productivity of 25.4 mg/l in batch cultivation. The resulting Cg-AsnB in the culture supernatant was subsequently purified using anion exchange and size exclusion chromatography, resulting in an overall yield of >12.8 mg/l. Although the productivity and purification yield remained to be further improved, the overall biochemical and structural properties of purified Cg-AsnB were comparable to those of commercially available Ec-AsnB. Taken together, these results could provide an alternative platform for the secretory production of L-asparaginase using endotoxin-free C. glutamicum as a host.

Influenza viruses remain a persistent threat to both human and animal health, whereas current countermeasures-vaccination and livestock culling-offer only delayed, partial, or economically burdensome protection. Here, we describe the development of a mucosal nanotherapy based on chromosome-free minicells derived from Lactiplantibacillus plantarum, engineered to surface-display a broadly reactive anti-hemagglutinin nanobody. These therapeutic agents, termed "neutralizing nanosomes" present nanobody molecules anchored on the minicell surface that retain full binding functionality against a broad spectrum of influenza viruses, including H1N1. Importantly, intranasal administration of neutralizing nanosomes effectively neutralized H1N1 infection in vivo, alleviating physiological symptoms and suppressing viral replication in the respiratory tract of a preclinical mouse model. Unlike vaccines, which require weeks to confer protection, our neutralizing nanosomes provide an immediate barrier at the respiratory mucosa-the primary portal of influenza entry-offering a promising adjunct to existing vaccines and antiviral drugs.

Influenza virus infections remain a major global health concern, causing annual outbreaks with high morbidity and mortality. The emergence of drug resistance and adverse effects from existing antivirals underscores the need for new therapeutic agents. This study presents the first evaluation of the antiviral activity and mechanisms of the dietary carotenoid lutein against influenza viruses. Lutein exhibited strong virucidal activity against influenza A (IAV) and B (IBV) viruses, as well as Japanese encephalitis virus (JEV), but showed only weak effects against the non-enveloped rotavirus, suggesting a preference for enveloped viruses. Dynamic light scattering analysis revealed that lutein disrupted viral particle integrity, causing aggregation and a reduction in particle numbers. Functional assays further demonstrated that lutein inhibited the activities of viral hemagglutinin (HA) and neuraminidase (NA). Lutein also suppressed viral replication when applied to cells both before and after infection, indicating its prophylactic and therapeutic potential. Collectively, these findings demonstrate that lutein exerts multifunctional antiviral effects through virucidal activity, inhibition of HA and NA activity, and suppression of viral replication. As the first report to elucidate lutein's multifaceted antiviral mechanisms, this study supports its potential as a natural antiviral candidate. In vivo studies will be essential to further assess its pharmacokinetics, efficacy, and safety for therapeutic applications against influenza.

The T7 RNA polymerase (T7 RNAP) system has revolutionized protein expression in Escherichia coli due to its high transcriptional activity and tight regulation. However, Salmonella enterica, despite its close genetic similarity to E. coli, lacks a T7 RNAP system, limiting the use of T7-based vectors and tools in this pathogen. Establishing a T7-compatible Salmonella strain would enable the seamless application of E. coli-optimized expression systems for studies in a pathogenic context. We engineered S. enterica serovar Typhimurium strain 14028s to stably express T7 RNAP from the chromosome under the control of the lac promoter using the pGRG36 transposon system. The resulting strain (Salmonella-T7) supports robust IPTG-inducible expression of heterologous proteins from T7 promoter-driven vectors, such as the pET series. Salmonella-T7 exhibited growth kinetics comparable to wild-type Salmonella in both rich and minimal media, indicating no detectable fitness cost. Furthermore, macrophage infection assays and murine infection models demonstrated that chromosomal integration of T7 RNAP does not compromise virulence. The engineered Salmonella-T7 strain enables efficient use of T7-based expression systems in S. enterica without affecting bacterial physiology or pathogenicity. This platform provides a valuable tool for studying bacterial pathogenesis as well as applications in synthetic biology and vaccine development.

Human norovirus (HuNoV) is a leading cause of acute gastroenteritis worldwide, causing severe illness and death in vulnerable populations, including infants and the elderly. Despite advances in norovirus vaccine candidates such as virus-like particles (VLPs), adenovirus-based oral vaccines, and mRNA vaccines, no vaccine has been approved yet. Current clinical trials primarily target the GI.1 and GII.4 genotypes responsible for most outbreaks. However, the extensive genetic diversity of HuNoV, along with continual antigenic evolution, poses significant challenges for developing broadly protective vaccines. Recent advances in experimental tools, including human intestinal enteroid cultures and surrogate neutralization assays, have improved norovirus vaccine efficacy assessment. Nevertheless, the lack of robust culture systems and animal models that faithfully mimic human infection continues to limit comprehensive evaluation of immune responses to diverse variants. Moreover, standardized correlates of protection, particularly those addressing mucosal immunity critical for infection prevention, remain to be established. This review integrates current immunogenicity assessment methodologies and evaluates ongoing HuNoV vaccine strategies, with emphasis on variant strain selection and platform technologies. We discuss key challenges related to population diversity, immune imprinting, and the complex interplay between systemic and mucosal immune responses as influenced by vaccine delivery routes and adjuvant formulations. By integrating recent advances in vaccine platforms, immunological tools, and delivery strategies, this review provides a framework for addressing critical obstacles in norovirus vaccine development. Such integrative perspectives are crucial for developing safe, effective, and broadly protective vaccines that offer meaningful benefits to global health.

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder associated with dysregulated immune responses and gut inflammation. In this study, lactic acid bacteria were isolated from various types of skate kimchi, and 100 strains were screened for their anti-inflammatory activity. WiKim0108 demonstrated potent suppression of nitric oxide production and proinflammatory cytokines (IL-1β, IL-6, TNF-α) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages without cytotoxic effects. Phylogenetic analysis based on 16S rRNA sequences confirmed that the strain was Pediococcus inopinatus, which is closely related to other species of the genus widely used in food fermentation. WiKim0108 was susceptible to 14 clinically relevant antibiotics and exhibited γ-hemolysis, indicating its safety for use in food applications. Enzymatic profiling revealed functional activities beneficial for food fermentation, including β-galactosidase activity, but β-glucuronidase activity was absent. In vitro, WiKim0108 enhanced immune responses, such as the proliferation of RAW 264.7 cells, production of NO and reactive oxygen species, and expression of immune-related genes. These immunomodulatory effects were validated in vivo through an increased population of innate and adaptive immune cells and the upregulation of immune-related genes. In a DSS-induced IBD mouse model, oral administration of WiKim0108 ameliorated clinical and histological symptoms by restoring the immune cell population and suppressing excessive expression of immune cytokine. Collectively, these findings indicate that P. inopinatus WiKim0108 is a safe and functional lactic acid bacterium with dual anti-inflammatory and immunomodulatory effects, highlighting its potential as a functional starter culture and bioactive food ingredient for promoting gut health.

Particulate matter (PM), a major pollutant of air pollution, contains a complex mixture of chemical and biological elements that pose significant threats to human health. Among the biological components, Stutzerimonas stutzeri PM101005 (PMSS), a bacterium isolated from fine dust, has been identified as a contributor to respiratory damage through inflammation. However, the mechanisms underlying its pathogenicity, particularly in comparison to environmental strains such as S. stutzeri (SS), remain unclear. In this study, we aimed to investigate the systemic effects of PMSS by comparing the serum metabolite profiles and inflammatory responses induced by SS and PMSS infections in a mouse model. Mice infected with PMSS exhibited marked alterations in serum metabolites, many of which were associated with enhanced pro-inflammatory signaling and the suppression of anti-inflammatory pathways. These metabolic changes were accompanied by elevated levels of circulating inflammatory cytokines, indicating a link between PMSS infection, metabolic dysregulation, and systemic inflammation. Our findings demonstrate that PMSS-associated bacterium, induces inflammation through modulation of host serum metabolites. This study suggests that PM-induced changes in serum metabolites contribute to inflammation, highlighting the need for further research on the systemic effects of biologically active components within particulate matter.