Archives of Microbiology最新文献

This study is aimed to utilize the lyophilized Limosilactobacillus reuteri 29B (L29B) strain with a high percentage of viable cells and essential probiotic properties in the development and evaluation of the probiotic vaginal pessary. Skim milk was identified as the optimal cryoprotectant for L29B giving 80.18% ± 0.123 viability after lyophilization. Hollow and solid type pessaries were formulated using polyethylene glycol (PEG) at different ratios. Both type of vaginal pessaries was detailed in further with regard to their physical properties. The hollow type vaginal pessary had an excellent stability and viability over a 24-month period at cold storage (68.22% ± 0.13) compared to solid type pessary (49.7% ± 0.59). It also completely disintegrated in the synthetic vaginal environment (pH 4.5) in less than 60 min and offered sustained in vitro release. It is demonstrated that the lyophilized process did not deteriorate the essential probiotic properties of L29B. These findings confirmed that the development of probiotic vaginal pessaries that involved the incorporation of lyophilized L29B into PEG 4000:400 (ratio 1:1) did not result in significant loss of viable cells and as a potential probiotic vaginal delivery system.

Salmonella encounters dual selective pressures during infection - from the host immune system and competing gut microbiota. The Type VI secretion system (T6SS) is a versatile transmembrane nanomachine that delivers effector proteins into target cells or the extracellular environment, enabling diverse functions including bacterial competition, virulence, and niche adaptation. Emerging evidence demonstrates that some T6SS effectors exhibit dual targeting capability, affecting both eukaryotic and prokaryotic cells. This dual-targeting strategy confers competitive advantages by simultaneously eliminating bacterial rivals through contact-dependent killing and subverting host defenses via apoptosis induction, facilitating niche domination. Although T6SS-mediated interbacterial competition is well characterized, the mechanisms by which Salmonella coordinately utilizes T6SS to circumvent host defenses and outcompete gut microbiota require elucidation. Here we synthesize recent advances supporting the T6SS effector dual-targeting hypothesis and propose an integrated niche adaptation model. We aim to provide a systematic review of the crosstalk between the T6SS of Salmonella and its host, spanning from past discoveries to current understanding and future perspectives. Our analysis provides a conceptual framework for understanding pathogenesis in Salmonella and related Gram-negative enteric pathogens, with implications for developing targeted intervention strategies.

Tuberculosis (TB) and lung cancer, two leading global health burdens, increasingly coexist, particularly in high-burden regions of these diseases. Epidemiological studies suggest TB significantly elevates lung cancer risk, as lung cancer increases the risk of TB, yet the molecular basis of this association remains underexplored. TB-induced chronic inflammation, oxidative stress, epithelial-mesenchymal transition (EMT), and immune checkpoint dysregulation create a permissive environment for oncogenesis. Granulomas and tumour microenvironments share immunosuppressive features, while overlapping host genetic and epigenetic signatures exacerbate diagnostic complexity. Immunotherapy in cancer risks TB reactivation, highlighting clinical tensions. Understanding the TB-lung cancer molecular interface is essential for developing integrated diagnostics and safe treatment regimens. This review integrates current evidence on the overlapping pathogenic, immunological and molecular landscapes of TB and lung cancer to identify shared mechanisms, diagnostic dilemmas and therapeutic challenges, while highlighting significant gaps needing actionable interventions. We also suggest some future paradigm shifts toward dual-disease research frameworks, critical to advance care in TB-endemic regions.

Chronic mucosal inflammation and decreased epithelial barrier function are hallmarks of inflammatory bowel disorders (IBDs), partially caused by dysregulated cytokine signaling. Researchers are looking into probiotics and their byproducts, called postbiotics, as safer options for broad immunosuppressants like cyclosporine. This study aimed on investigating the effect of metabolites derived from Lactobacillus reuteri (ATCC 23272) on lipopolysaccharide (LPS)-induced inflammation model of HT-29 epithelial cells. Cell viability (MTT), apoptosis (Annexin V-FITC flow cytometry), cytokine expression (IL-4, IL-10, IL-17), and gene transcription (IL-8, IL-10) were evaluated after treatment of in vitro induced model comparing metabolites with cyclosporine (conventional therapy used for IBD treatment) at different time points. Using a 50% postbiotic solution increased the viability of HT-29 cells (≈ 140%, p < 0.0001) showing no cytotoxicity. In inflamed conditions, IL-17⁺ cells decreased by almost 50% (0.48-fold compared to LPS+, p < 0.0001), although IL-10⁺ cells exhibited a little increase (1.1-fold compared to LPS+, p = 0.0023). By day 5, IL-8 expression was significantly downregulated at the transcriptional level (p = 0.0121), with effects that were stronger than those of cyclosporine (p = 0.0040). In general, L. reuteri metabolites brought back apoptosis, lowered IL-8 and IL-17 levels while sustaining IL-10 increased, thus affecting immunological milieu of the epithelium toward resolution. These results were comparable or even superior to those of cyclosporine, indicative of the stability and safety of postbiotics as good candidates for IBD treatment. Additional research utilizing intestinal organoids and animal models is advised to validate their therapeutic efficacy.

Actinobacteria have a huge, mainly untapped potential for the production of secondary metabolites. These metabolites are an important source of bioactive compounds. However, a majority of biosynthetic gene clusters (BGCs) are either under-expressed or fully silent under standard laboratory conditions, limiting their potential. The present review article aims to explore the biosynthetic gene clusters (BGCs) of actinobacteria using strategies that aid in unlocking these silent BGCs. The strategies discussed are PCR-Targeted Gene Replacement (PCR-TR); Cre-LoxP recombination system; Transcription factor decoys, Ribosome engineering, and CRISPR/Cas technologies. Besides, elicitors also helped with the identification of these cryptic or silent BGCs and advanced our ability to explore these natural products. Combining experimental and computational platforms provides an opportunity to unlock the hidden chemical diversity in nature, thereby accelerating the identification of new bioactive substances. The new antibiotics explored by all the strategies could help in the fight against antimicrobial resistance (AMR).

Graphical Abstract

Antimicrobial resistance (AMR) is a global health concern that requires innovative therapeutic strategies to improve clinical outcomes. Bacterial priority pathogens have developed multiple mechanisms for AMR. To develop therapeutics to overcome AMR, it is essential to explore, understand, and identify effective molecular targets. Iron is crucial for survival and pathogenesis in bacterial physiology. Reports indicate that iron supports vital cellular functions and modulates bacterial virulence and pathogenicity. Due to the bacterial requirement for iron during infection, antimicrobials are being developed by targeting iron homeostasis pathways in pathogens. In this review, we explore the virulence, AMR, and iron homeostatic mechanisms in bacterial pathogens, as well as the functional role of iron in regulating virulence, antimicrobial resistance, and other aspects of bacterial physiology, to elucidate potential therapeutic strategies against drug-resistant pathogens. This review briefly discusses therapeutic interventions based on iron homeostasis mechanisms and the associated translational challenges.

Plasmid-driven metabolic burden in Escherichia coli poses a critical challenge for industrial terpenoid production, yet the molecular origins of transcriptional stress remain unclear. Here, we engineered geraniol-producing E. coli strains with isogenic plasmid DNAs differing only in promoter architecture (Trc vs. T7, single vs. dual promoter) to dissect transcriptional versus translational contributions to plasmid instability. Dual promoter-driven strains exhibited acute production failure (92.1–94.8% reduction in peak geraniol titers) compared to the single Trc promoter control, accompanied by acute growth inhibition (34.6–37.9% lower specific growth rates). Remarkably, > 53% of this metabolic burden persisted after RBS/MCS deletion (calculated as [growth inhibition in S528]/[inhibition in S493] × 100%), directly linking instability to transcription initiation rather than protein synthesis. Promoter strength inversely correlated with plasmid retention: dual-T7 constructs reduced plasmid stability to 45.0 ± 9.5% within 12 h post-induction, while Trc systems maintained 80.0 ± 4.8% retention. Partial host adaptation restored cell growth (47% recovery by 12 h), but geraniol titer remained severely suppressed (21.7% of control), revealing irreversible metabolic flux imbalances. These findings reveal that strong promoters induce plasmid instability primarily through transcription-initiated burden, distinct from translational costs. Our work provides a genetic uncoupling strategy to quantify this burden and guides promoter optimization for stable microbial terpenoid production.

Cold atmospheric plasma (CAP) is an innovative, non-thermal decontamination technology with promising applications in food safety. This study investigated the antimicrobial mechanisms of CAP against the foodborne pathogens Salmonella Typhimurium and Listeria monocytogenes. CAP was applied using piezoelectric direct discharge (PDD) technology for 0, 1, 6, 9, and 15 min to simulate nonthermal decontamination conditions relevant to food processing. Antimicrobial effectiveness was evaluated using culture-based enumeration, while CAP-induced cellular damage was assessed using scanning electron microscopy (SEM), and assays measuring lipid peroxidation, reactive oxygen species accumulation, membrane permeability and malate dehydrogenase activity. Bacterial viability significantly decreased by up to 5.7 log CFU/mL after 6 min and ≤ 6.6 log CFU/mL after 9 and 15 min treatments, compared with untreated pathogens. These reductions were accompanied by corresponding increases in membrane permeability of 50%, 65%, and 94%, respectively. Culture-based enumeration confirmed reductions of ~ 4.5 log CFU/mL after 6 min and ≤ 6.5 log CFU/mL following 9 and 15 min treatments. CAP treatment for at least 6 min significantly elevated intracellular reactive oxygen species, which triggered lipid peroxidation as evidenced by elevated malondialdehyde and peroxide values. Furthermore, CAP treatment resulted in a significant reduction in malate dehydrogenase activity, indicating disruption of cellular metabolic function. SEM supported CAP-induced cellular alterations by revealing morphological damage, including porosityshrinkage and cytoplasmic leakage. Overall, PDD-generated CAP induced a multi-targeted antimicrobial effect, supporting its potential as a nonthermal decontamination method in food processing. Further research should focus on its application to a range of food matrices and its impact on quality parameters.

Microplastics transport toxins, disrupt microbial and nutrient cycles, bioaccumulate to cause oxidative stress and endocrine disruption, jeopardizing ecosystems and human health. Despite understanding microplastic origins, distribution, and microbial degradation biotechnological remediation efforts remain fragmented and largely at the proof-of-concept stage. Recent high-throughput meta-omics has uncovered diverse plastisphere associated enzymes, while metabolic engineering platforms have demonstrated programmable biofilm trap-and-release mechanism and enzymatic upcycling of PET monomers; however, the translation of these technologies to diverse polymer classes and field applications is limited. Machine learning is emerging as a powerful tool to uncover efficient microplastic degradation strategies, a domain previously underexplored. This review critically synthesizes these interdisciplinary advances spanning microbial and enzymatic remediation evolution, metabolic-engineering architectures for capture and valorization, and AI-driven monitoring to identify persistent bottlenecks and propose a unified roadmap for deploying sustainable, biotechnology-driven solutions that can be scaled to address the global microplastic crisis. By bridging these domains, we aim to inform future research priorities and accelerate the translation of laboratory findings into industrial scale mitigation strategies.

Zearalenone contamination poses a continuing threat to food security and the health of the livestock industry; developing efficient, high-yield detoxifying enzyme formulations is therefore essential. This study aimed to achieve the high-level expression of zearalenone lactonohydrolase ZenG in Pichia pastoris. The resulting recombinant ZenG exhibited optimal activity at pH 8.0 and 50 °C, with a specific activity of 684 ± 2.17 U/mg. Replacing the α-factor signal peptide with the pre-Ost1-pro-α-factor signal peptide increased ZenG activity from 180.26 U/mL to 276.47 U/mL. Subsequent optimization of the gene dosage further boosted the yield to 479.52 U/mL. Co-expression of the molecular chaperones 100p-HAC and 55p-HAC1 elevated the enzyme activity to 557.85 U/mL and 582.01 U/mL, which correspond to 3.09-fold and 3.23-fold increases, respectively, compared to the initial G-α-ZenG strain. In conclusion, this study successfully constructed an engineered P. pastoris strain capable of highly efficient ZenG production, laying a solid foundation for its industrial-scale application.