Archives of Microbiology最新文献

The growing demand for innovative and pesticide-free pest management in global food production has accelerated the development of environmentally friendly alternatives. Among these, biopesticides based on Bacillus thuringiensis (Bt) have emerged as a leading substitute. Renowned for their specificity and effectiveness in controlling agricultural pests, Bt biopesticides face limitations in field applications, primarily due to formulation instability and degradation of insecticidal proteins under ultraviolet (UV) exposure. Recent advancements in formulation have provided new opportunities for creating more efficient formulations of Bt that can address these challenges, enabling the development of more stable, efficient, and targeted Bt formulations. This review highlights recent advancements in formulation, including nanotechnological approaches for improving Bt-based biopesticides. Nanotechnological approaches include encapsulation techniques, coating, nanopesticides, nanoemulsions, nanosuspensions, nano-carriers for targeted delivery, and nano-formulations for controlled release and pest specificity. These interventions to enhance the efficiency and sustainability of Bt-based biopesticides can increase their adoption in agricultural pest management around the globe.

As core microbiota in the intestine, Veillonella and Lactobacillus regulate the dynamic balance of lactic acid and short-chain fatty acids (SCFAs), and maintain intestinal homeostasis through synergistic metabolism. This study investigated the synergistic metabolism of Veillonella ratti (V. ratti) and Lactobacillus acidophilus (LA-85), and evaluated their combined protective effects against Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157:H7) infection using a piglet intestinal ligation model. Mono-cultures and co-culture were conducted using the modified medium. During cultivation, the changes in viable counts, OD₆₀₀, pH, lactic acid, glucose, and SCFAs were monitored, as well as the effects on the expression of EHEC virulence genes. In the piglet intestinal ligation experiments, histological examinations, virulence gene detection, and microbiota analysis were performed on different ligated intestinal segments. In the modified medium, co-culture significantly increased the viable counts, OD₆₀₀, and SCFAs production, compared with mono-cultures. Co-culture suppressed the expression of EHEC virulence genes in vitro. In the piglet intestinal ligation experiments, combined administration of V. ratti and LA-85 ameliorated EHEC-induced intestinal inflammation, inhibited the formation of attaching and effacing lesions, and significantly down-regulated the expression of EHEC O157:H7 virulence genes. Furthermore, all the ligated segments exhibited obvious inflammation and Proteobacteria expansion. The intervention altered the ligation segments’ microbiota composition. These findings demonstrate that V. ratti and LA-85 synergistically inhibit EHEC O157:H7 infection. The underlying mechanism involves suppressing virulence gene expression in the pathogen and inhibiting the attaching and effacing lesions formation. This study demonstrates the potential application value of this combined probiotic strategy.

Bacteria are constantly challenged by osmotic pressures in their natural environments, necessitating sophisticated detection, signal transduction, and response systems for survival. These osmotic stress responses are intricate and involve multi-level control processes that are crucial for bacterial homeostasis. A significant factor influencing osmotic regulation is the morphological structure of bacteria, notably the distinct cell wall compositions of Gram-positive and Gram-negative types, which directly impact their regulatory mechanisms. This review focuses on contrasting the osmotic regulation systems between Gram-positive and Gram-negative bacteria, exploring their preferences for compatible solutes, the essential role of c-di-AMP in Gram-positive bacteria, and unique gene domains in two-component systems (TCS). By highlighting these distinctions, the review aims to deepen the understanding of how these systems function and their implications for bacterial virulence, pathogenicity, survival, and reproduction. Exploiting structural vulnerabilities in pathogen-specific TCS offers routes to narrow-spectrum antimicrobials that spare commensal microbiota. Such insights are pivotal for understanding bacterial adaptation within diverse hosts and environments.

Large numbers of bacteria can enter a viable but nonculturable (VBNC) state to survive adverse conditions, and antibiotic-resistant Escherichia coli cells in a VBNC state pose public health risks. This study aimed to investigate whether prolonged exposure to environmentally relevant concentrations (10 µg/L) of two typical antibiotics, ciprofloxacin and sulfadiazine, could induce Escherichia coli to enter the VBNC state and whether cells regrown from this state would exhibit multidrug resistance. Experimental results showed that after exposing to 10 µg/L ciprofloxacin and sulfadiazine for consecutive 10 days, cultivability of E. coli decreased significantly (p < 0.05) and entered VBNC state. E. coli in VBNC state started to recover in nutrient-rich Luria-Bertani (LB) broth after 16 h at 37 °C. Minimum inhibition concentration (MIC) measurements demonstrated that ciprofloxacin- and sulfadiazine- induced regrown E. coli were resistant to nine commonly used antibiotics, including amoxicillin, ampicillin, chloramphenicol, ciprofloxacin, colistin, enrofloxacin, kanamycin, sulfadiazine, and tetracycline. Quantitative reverse transcription-polymerase chain reaction assays showed that efflux pumps were activated when bacteria challenged with antibiotics. In addition, genes related to oxidative stress and outer membrane porins up-regulated significantly (p < 0.05) in VBNC E. coli cells. Consequently, morphological alterations in cell membrane were observed after antibiotics’ treatment. This study reveals that antibiotic at environmentally relevant concentrations can induce E. coli to enter VBNC state with multidrug resistance, enhancing our grasp of health risks from antimicrobial resistance, antibiotics, and VBNC bacteria in environmental settings.

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Bone tuberculosis (BTB) remains a diagnostic and therapeutic challenge despite advances in molecular medicine, accounting for 10–15% of extrapulmonary tuberculosis cases with disproportionate morbidity in immunocompromised populations. This comprehensive review synthesizes current understanding of BTB pathogenesis, diagnostic innovations, and therapeutic strategies while highlighting critical knowledge gaps. At the molecular level, Mycobacterium tuberculosis exploits bone-specific niches through granuloma formation, immune evasion mechanisms involving autophagy inhibition and cytokine dysregulation, and direct disruption of RANKL/OPG signaling that drives osteoclastic bone destruction. Clinically, BTB exhibits distinct phenotypes, with vertebral (spinal) disease characterized by delayed diagnosis, higher relapse rates, and frequent need for surgical intervention, whereas peripheral joint and long bone involvement often presents with indolent synovitis and diagnostic overlap with inflammatory or degenerative disorders. Pediatric BTB represents a distinct entity, frequently involving growth plates, displaying marked paucibacillary disease that limits microbiological confirmation, and carrying substantial risk of long-term skeletal deformity. Multi-omics approaches have identified novel biomarkers, including microRNAs (miR-29, miR-125b), long non-coding RNAs (MALAT1, NEAT1), and protein signatures (calprotectin, lipocalin-2) with diagnostic potential, though clinical validation remains limited. Conventional imaging modalities are complemented by emerging molecular diagnostics, such as GeneXpert MTB/RIF Ultra, which promise earlier and more accurate diagnoses. Standard anti-tuberculosis regimens face substantial challenges in skeletal tissues due to avascular lesions, granuloma microenvironments, and rising drug resistance, necessitating prolonged treatment durations with suboptimal outcomes. Novel therapeutic paradigms encompass bone-targeted nanotechnology-enabled drug delivery systems. Critical barriers to clinical translation include technical limitations in bone tissue multi-omics analysis, significant gaps in genetic diversity across research cohorts, regulatory hurdles to combination therapies, and healthcare inequities in resource-limited settings. The future roadmap integrates AI-assisted multimodal data integration to enable personalized BTB management that simultaneously addresses pathogen elimination, immune restoration, and bone regeneration.

Lawsonia Intracellularis (L. intracellularis) is an obligate intracellular bacterium that causes porcine proliferative enteropathy. In this study, a pan-RV (reverse vaccinology based on pangenome analysis) approach was applied to analyze the whole-genome sequences of 9 L. intracellularis strains downloaded from the National Center of Biotechnology Information (NCBI) server. Pangenome analysis revealed a closed pangenome and a core genome consisting of 1372 genes, while reverse vaccinology further revealed 16 candidate proteins with higher in silico immunogenicity parameters, including predicted antigenicity, “outer membrane protein” or “extracellular protein” by subcellular localization analysis and no more than 2 transmembrane regions by transmembrane helices prediction. Three of the 16 proteins that showed no homology with proteins of other species according to BLAST (Basic Local Alignment Search Tool) were selected for serological validation. The Western blotting results revealed that the 3 proteins did not cross-react with anti-Shigella and anti-Salmonella sera, with 1 protein (LAW_RS03650) showed antigenicity when it reacted with positive wild-type anti-L. intracellularis serum. The immunofluorescence of infected cells employing anti-LAW_RS03650 serum indicated a wide distribution of LAW_RS03650 protein in the host cells and L. intracellularis itself. This study identified a novel L. intracellularis antigen, LAW_RS03650, as a candidate for future recombinant vaccine development or species-specific serodiagnostic reagents.

The complement system is a serum-borne set of over 30 inactive liver-derived proteins, components that activate in a proteolytic cascade when pathogens invade. Activation of complement system promotes phagocytosis, inflammation, and direct microbial lysis. Complement targets pathogens through three main pathways: classical, lectin, and alternative. Together, these innate defenses mediate pathogen recognition and elimination. This study investigated complement activation against American Type Culture Collection (ATCC) 9144 and Multidrug-Resistant (MDR) Staphylococcus aureus, focusing on whether complement proteins play a key role in combating S. aureus. All experiments were performed in vitro using sera collected from healthy individuals. Enzyme-linked immunosorbent assay (ELISA) was employed to detect complement proteins (C1q, MBL, Ficolin-L, Ficolin-H, Ficolin-M, CL-11), and complement activation assays (C3, C4, C5, factor Bb, and MAC deposition assays). Findings showed that lectin, classical, and alternative complement pathways collectively drove C3 activation on S. aureus surface. However, C5b deposition onto the bacterial surface was weaker, and C9 failed to integrate, preventing Membrane Attack Complex (MAC) mediated lysis. Additional serum bactericidal and phagocytosis assays revealed that S. aureus resisted complement-mediated killing under the in vitro conditions used. Notably, complement recognition and activation profiles of MDR isolate were similar to or stronger than non-resistant strains, highlighting complement’s importance in targeting MDR S. aureus.

Cryptic genes are phenotypically silent DNA sequences with the potential to code for a function but remain inactive during the normal life span of the organism. However, they can be activated by a single mutational event such as recombination, deletion, insertions or point mutation, resulting in a discernible phenotype. These phenotypes impart a growth advantage to the bacteria under stress and harsh living conditions. The bgl operon of Escherichia coli is involved in the uptake and breakdown of plant-derived aromatic β-glucosides like salicin and arbutin, is one of the well-studied examples of a cryptic genetic system. Previous studies have shown that the activated allele of the operon is beneficial to bacteria under selective conditions such as, survival in long term stationary growth phase, in the presence of predators, and antibiotics. All the observations point towards the possibility of the having a growth disadvantage and therefore a fitness cost associated with the activated operon under nonselective or less stressful conditions. To test the hypothesis the pair-wise competition experiments under nutrient-rich growth conditions using strains of different bgl genotypes were conducted. We report that a strain expressing the bgl operon constitutively, thus bypassing the requirement for a β-glucoside inducer, does not exhibit a measurable growth disadvantage over a strain carrying the wild type (silent or non-activated) bgl locus. These results imply that the classic cost-benefit model of bet-hedging may not be universally applicable and fitness trade-off might be more nuanced, existing only under specific environmental or resource-limited conditions.

The antibiotic exploitation has escalated the menace of drug-resistant bacteria, necessitating the development of powerful new drugs. Gold nanoparticles (Au NPs) are ideal bactericidal agents due to their unique physicochemical properties, non-toxicity, inertness, and biocompatibility. The surface properties of Au NPs have a critical role in their antibacterial activity. This review summarizes the data of published literature from 2001 to 2025 on the various physio-chemical and biological methodologies for synthesizing Au NPs and their antibacterial functions. The ability of the Au NPs to transform the near-infrared light into heat has demonstrated the photothermal-based bacterial death due to excessive heat generation. Engineering and functionalization of Au NPs with antibiotics/antimicrobial compounds/phages/enzymes have been shown to enhance antibacterial efficacy through targeted drug therapy by making the bacteria extremely vulnerable to these combinations. The complexity, cost-ineffectiveness, and lack of standardized protocols for Au NP synthesis can limit their adoption for antibacterial purposes. Resistant strains may develop from the prolonged and sublethal exposure of Au NPs. The in-vivo studies on animal models have confirmed the aggregation of Au NPs in the vital organs, bringing developmental, genotoxic, and cytotoxic effects. The unforeseen consequences on humans and the environment by long-term exposure to Au NPs have not yet been determined, thus restricting their applications for antibacterial therapy. Meticulous research on Au NPs and their combination therapy along with AI-driven approaches will promote the translation of Au NPs into clinical trials by uncovering their bioavailability, safety, distribution and mechanism before validating them for antibacterial therapy.

Bacterial β-carbonic anhydrases (β-CAs) are actively studied as potential targets for next-generation antibacterial agents. Despite extensive biochemical and structural characterization, their validation as isoform-specific therapeutic targets remains incomplete. Here, we developed and applied a six-filter validation framework—encompassing genetic essentiality, physiological relevance, biochemical feasibility, structural rationale, cellular target engagement, and therapeutic context—to integrate disparate data into a strategic prioritization map across representative pathogens (Escherichia coli, Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Streptococcus pneumoniae). Application of this framework reveals that none of the analyzed β-CA isoforms currently qualifies as a ready therapeutic candidate (Group A), with most falling into context-dependent (Group C) or high-risk (Group D) categories due to specific validation gaps. By systematically defining these gaps, the framework provides a prioritized, target-driven roadmap for future experimental design and antibacterial drug discovery targeting bacterial β-carbonic anhydrases.