Archives of Microbiology最新文献

A common vaginal dysbiosis, bacterial vaginosis (BV), has serious consequences for reproductive health, including an elevated risk of infertility and pelvic inflammatory disease. Its distinctive feature is a robust polymicrobial biofilm, mainly composed of Gardnerella species (spp.), which protects infections against antibiotic therapy and promotes high rates of recurrence. Concurrently, Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection globally, with over 130 million new cases annually. A primary cause of tubal factor infertility, CT infection promotes adnexal adhesions and fallopian tube obstruction through inflammatory damage. This article reviewed two critical agents: CT, an intracellular bacterium that causes inflammatory tubal damage, and BV, caused by biofilm-forming pathogens such as Gardnerella. The growth of antimicrobial resistance underscores the critical need for targeted alternatives to broad-spectrum antibiotics. Endolysins, enzymes that break down bacterial cell walls, are produced by bacteriophages (phages) and represent a potential new treatment approach. This paper summarizes evidence that modified endolysins, such as PM-477, can specifically break down Gardnerella biofilms in vitro and ex vivo while preserving beneficial vaginal lactobacilli. We examine how this precise mechanism addresses the fundamental shortcomings of existing BV treatment. Then, to transform phage-derived techniques from an intriguing preclinical concept into a workable therapeutic intervention for recurrent BV, we critically assess the key translational obstacles that must be addressed, including pharmacokinetics, formulation, and the need for clinical trials.

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This study investigated the aerobic biodegradation potential of two novel indigenous bacterial strains, Pseudomonas aeruginosa DUT-Pa and Rhodococcus erythropolis DUT-Re, utilizing benzene, toluene, ethylbenzene, and o-xylene (BTEX) as the sole carbon source. The optimal metabolic activity for both strains was identified at neutral pH (7.0) and mesophilic conditions (30 °C), establishing a critical baseline for enhancing bioremediation protocols. Biochemical oxygen demand (BOD) analysis revealed a direct correlation between the substrate concentration (up to 400 mg/L) and microbial respiratory activity. Dissolved oxygen (DO) depletion from 7.77 mg/L (pre-experiment) to 2.97 mg/L (DUT-Pa) and 2.15 mg/L (DUT-Re) further confirmed the oxygen-dependent degradation. In the gas phase, the highest degradation rate was recorded for benzene, with 98.43, 97.34, and 98.91% by DUT-Pa, DUT-Re, and mixed bacteria, respectively. Meanwhile, the liquid phase demonstrated superior toluene degradation efficiency by DUT-Pa, DUT-Re, and mixed bacteria with 91.99, 83.54, and 93.27% respectively. Bacterial combinations enhanced BTEX degradation, achieving the shortest half-lives and the highest degradation rate constants. Meanwhile, the SOD (325 U/mL) level and MDA (1.5 to 2.59 nmol/g) increased in the mixed system. This study demonstrates that an additive effect of DUT-Pa and DUT-Re combination promotes efficient, complete degradation of BTEX and offers a scalable, eco-friendly solution based on strain-specific cooperative microbial dynamics.

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The accumulation of plastics in aquatic environments is a growing global concern, as biofouling on plastic debris leads to the formation of the plastisphere, an ecological niche for diverse microbial and macrofouling organisms. Although plastic characteristics such as size, color, and polymer type may influence plastisphere development, there is no consensus regarding their relative importance, and studies in estuarine environments remain scarce. Here, we investigated plastisphere formation across three salt marsh zones (dry, intermediate, and flooded) in the Patos Lagoon estuary (southern Brazil), considering variations in plastic size (6 × 2, 30 × 10, and 60 × 20 mm), color (white, black, and red), and polymer type (Polypropylene—PP, Polystyrene—PS, and Ethylene Vinyl Acetate—EVA). Three independent 21-day field experiments were conducted, and plastisphere development was assessed using multiple complementary approaches, including biomass (weight), bacterial density, photosynthetic pigment composition, macrofouling abundance, and DNA metabarcoding of bacterial (16S rRNA) and fungal (ITS) communities. Plastisphere development consistently followed the flooding gradient, with higher biomass, microbial density, and photosynthetic pigment concentrations in flooded and intermediate zones compared to the dry zone. Smaller plastic substrates favored microbial colonization, whereas larger substrates supported higher macrofouling abundance. Polymer color and type modulated colonization patterns of specific taxa, with EVA substrates showing higher biofilm accumulation. Community-level analyses revealed that flooding regime was the driver structuring bacterial and fungal community composition, with higher richness, diversity, and evenness in the intermediate zone. Differences among zones were driven mainly by shifts in the relative abundance of shared taxa rather than taxonomic turnover. Overall, this study demonstrates that environmental context, particularly flooding regime, outweighs plastic characteristics in shaping plastisphere communities in salt marshes, providing new insights into plastisphere dynamics in understudied Neotropical estuarine ecosystems.

Acinetobacter baumannii (A. baumannii) is recognized as an ESKAPE pathogen and a major cause of nosocomial infections. Despite advances in understanding the pathogenesis of A. baumannii and host immune responses, the direct interactions between A. baumannii and immune cells, as well as their influence on bacterial behavior, remain poorly defined. To address this gap, the present study established an in vitro model by co-culturing A. baumannii with human peripheral blood mononuclear cells (PBMCs) to investigate these interactions. A. baumannii isolated from patients’ pneumonia samples was co-cultured with PBMCs and their cell-free supernatants. After 24 h, the proliferation and viability of PBMC, the CFU count of bacteria, the PBMC cytokine profile, immune evasion gene expression (bap and ompA), biofilm formation, and bacterial motility were investigated. Co-culture with A. baumannii has significantly reduced the proliferation and viability of PBMCs compared with PBMCs alone. No significant change in bacterial CFU was observed in the co-culture group and cell-free supernatant. Cytokine analysis revealed a marked increase in TNF-α, whereas the production of IL-6 and IL-10 decreased in the co-cultured groups. Gene expression analysis revealed significant downregulation of bap in interaction with PBMC, whereas ompA expression remained unchanged. Co-culturing bacteria with PBMC resulted in an increase in biofilm formation; however, this difference was not statistically significant. Furthermore, there was no significant difference in surface-associated motility and twitching motility in the co-culture and bacterial alone groups. Overall, this is the first study to show direct interaction of A. baumannii and human PBMCs. The findings indicate that A. baumannii impairs the proliferation and viability of immune cells, while simultaneously resisting immune-mediated clearance. Interestingly, the downregulation of the biofilm-associated bap gene and the inflammatory microenvironment did not lead to significant changes in bacterial growth, biofilm formation, or motility. These findings demonstrate the robust resistance of A. baumannii to human immune defenses, underscoring the challenges in controlling and treating infections caused by this pathogen.

Carbon dioxide (CO₂) constitutes approximately two-thirds of total anthropogenic greenhouse gas emissions and therefore represents the primary target for mitigation strategies. Among the available approaches, algal-based CO₂ capture has emerged as a promising biological option due to the high photosynthetic efficiency, rapid growth rates, and capacity of microalgae to utilize concentrated CO₂ streams directly from industrial point sources. Under optimized laboratory and pilot-scale conditions, algal systems have been reported to achieve CO₂ fixation rates in the range of approximately 0.1–1.5 g CO₂ L^–1 d^–1, corresponding to areal biomass productivities of roughly 10–40 g m^–2 d^–1, depending on species, reactor configuration, and environmental conditions. This review critically evaluates the potential of algal-based systems for CO₂ biofixation, with particular emphasis on algal carbon assimilation mechanisms, cultivation strategies, and operational constraints relevant to large-scale deployment. Key parameters influencing CO₂ capture efficiency, including light irradiance, pH, nutrient availability, and gas–liquid mass transfer are systematically discussed. The role of algal–bacterial consortia in enhancing carbon utilization and enabling integration with wastewater treatment processes is also examined. Furthermore, the review compares open and closed cultivation systems, highlighting trade-offs among productivity, energy demand, contamination risk, and economic feasibility. While emerging approaches such as hybrid cultivation concepts and process-intensification strategies offer pathways to improve system performance, their practical implementation remains constrained by downstream processing costs and scale-up challenges. Overall, the analysis suggests that algal-based CO₂ mitigation is most effective when deployed as part of integrated biorefinery frameworks, particularly in conjunction with wastewater treatment and value-added biomass utilization—rather than as a standalone carbon sequestration solution. This integrated perspective provides a balanced assessment of the opportunities and limitations of algae-based CO₂ mitigation within sustainable climate and environmental management strategies.

The adhesion of bacterial cells through extracellular matrices plays a critical role in biofilm formation. Disrupting these matrices offers a promising strategy to overcome the persistent challenge of eradicating biofilms associated with chronic infections. CsgA, a major functional amyloid within the extracellular matrix of Escherichia coli (E. coli), adopts a β-sheet-rich conformation that contributes to the structural integrity of biofilms. The stability of these β-sheets is maintained by an extensive hydrogen-bonding network within the protein, and their disruption can compromise biofilm viability. In this study, computational approaches were employed to identify anti-biofilm peptides capable of targeting the β-sheet structures of CsgA amyloid. Among 41 screened peptides, 10 were predicted to be toxic, and the remaining 31 were subjected to molecular docking and reactivity analyses. The HOMO–LUMO energy gap was evaluated before and after docking to assess peptide reactivity, identifying 22 peptides with high reactivity for further dynamic simulations using discrete molecular dynamics. Comparative analyses revealed that Brevinin-1BW, Kassinatuerin-3, Ranateurin-2Awa, Temporin-B, and Magainin-I-KL decreased the β-sheet content of CsgA relative to the untreated protein. Notably, Magainin-I-KL induced a 7% reduction in β-sheet content and substantial structural disruption, as evidenced by decreased hydrogen bonding, increased metastable states in the free-energy landscape, and deformation patterns in cross-correlation analysis. Steered molecular dynamics simulations further demonstrated that Magainin-I-KL exhibited greater resistance to force-induced dissociation, indicating stronger interactions with CsgA. Overall, Magainin-I-KL effectively destabilizes the CsgA amyloid structure of E. coli, suggesting its potential as a lead peptide for disrupting amyloid-based biofilm formation and enhancing antimicrobial strategies.

Antibiotic resistance has significantly constricted the therapeutic efficacy of antibiotics on treating bacterial infections, creating an urgent need for new antimicrobial agents. However, progress in developing these agents is slow, prompting the exploration of innovative strategies such as combination therapy. This study examined the combined effects of Temporin antimicrobial peptides with antibiotics against Escherichia coli and Pseudomonas aeruginosa. We found that Temporin-GHaR (GHaR) and Temporin-GHaK (GHaK) with polymyxin B (PMB) showed synergistic antibacterial activity against P. aeruginosa and E. coli, with a fractional inhibitory concentration index (FICI) below 0.5. Further mechanistic studies revealed that the combination of GHaR/GHaK with PMB significantly enhanced the bactericidal effect by synergistically augmenting the disruption of the outer and inner membranes of P. aeruginosa and E. coli. Meanwhile, this combination regimen demonstrated efficacy in inhibiting the biofilm formation of P. aeruginosa and E. coli at concentrations lower than those required for single-drug treatments, and enhanced the disruption of mature E. coli biofilms. The synergistic use of GHaR/GHaK and PMB augmented the antibacterial efficacy against P. aeruginosa and E. coli without increasing hemolytic toxicity to murine erythrocytes. These findings provide an experimental foundation and theoretical framework for the application of conventional antimicrobial agents.

Agro-industrial processes generate significant lignocellulosic waste, composed mainly of cellulose, hemicellulose, and lignin. Repurposing these residues for lignocellulolytic enzyme production offers an economical, sustainable approach to biomass valorization and the generation of bioproducts such as lactic acid. This study aimed to optimize enzyme production by Aspergillus species grown on various agro-industrial residues and apply these enzymes to hydrolyze barley bagasse for lactic acid production. Four Aspergillus strains (A. brasiliensis, A. clavatus NRRL1, A. flavus, and A. terreus) were cultivated in minimal medium (pH 6.5) with 1% (w/v) Barley Bagasse, Bean Straw or Rice Straw, at 30 °C and 120 rpm for five days. Nine different holocellulolytic activities were screened using natural and synthetic substrates. A. brasiliensis exhibited the highest enzymatic activity when grown on bean straw. Optimization of its cultivation led to 10 g/L of reducing sugars after five days at pH 5.5 and 35 °C. Subsequent optimization of barley bagasse hydrolysis resulted in 49 g/L of fermentable sugars when using 20% (w/v) of this substrate concentration, at pH 3.0, and 50 °C for 24 h. This corresponded to a hydrolysis yield of 44% relative to the total carbohydrate content. The released sugars were fermented by Lactobacillus rhamnosus ATCC 7469, producing 21.1 g/L of L-lactic acid corresponding to a fermentation yield of 47% relative to the available sugars and a volumetric productivity of 0.15 g/L/h. This work demonstrates an integrated bioprocess that couples low-cost enzyme production with effective saccharification and fermentation of barley bagasse. This approach underscores its potential for sustainable lactic acid production. Unlike previous studies that rely on commercial enzymes or neutral-pH hydrolysis, this process uniquely combines acid-tolerant enzymes produced by Aspergillus brasiliensis grown on bean straw, a rarely used substrate, with direct fermentation by Lactobacillus rhamnosus ATCC 7469 at low pH. The integration of these specific microbial species and agro-residues represents a distinctive and effective approach to biomass valorization.

The increasing demand for functional foods has stimulated research on probiotic strains with health-promoting properties. This study investigated the biofunctional traits of the putative exopolysaccharide (EPS)-producing strain Lactiplantibacillus plantarum Lbio1 and evaluated its survival, both free and encapsulated, under simulated gastrointestinal conditions. Safety assessment indicated the absence of haemolytic and gelatinase activities and susceptibility to most tested antibiotics. The strain tolerated acidic pH (2.0) and bile salts (0.3% w/v) with survival rates of 72 and 83%, respectively, and exhibited bile salt hydrolase activity. The strain also grew in 0.1% (v/v) phenol. Adhesion-related properties included high auto-aggregation (92%) and co-aggregation with pathogenic strains (Escherichia coli ATCC 25522, Staphylococcus aureus ATCC 43300, and Micrococcus luteus ATCC 49732), ranging from 43.9 to 71.5%, as well as a biofilm formation capacity, despite exhibiting low hydrophobicity (16%). Cholesterol assimilation reached 82%. The EPS produced by Lbp. plantarum Lbio1 was a high molecular weight heteropolymer composed of glucose and galactose. The encapsulation of Lbp. plantarum Lbio1 in alginate beads (≈ 3 mm, 91% efficiency) efficiently loaded cells, as observed by scanning electron microscopy, and enhanced their survival under simulated gastrointestinal stress. Encapsulated cells retained viability above 10⁶ CFU/g for 34 days at refrigeration temperature, despite a viability loss of approximately 1 log CFU per week. These findings highlight the probiotic potential of Lbp. plantarum Lbio1 and the efficiency of encapsulation in improving bacterial cell survival.

The central challenge in brucellosis prevention and control stems from the marked heterogeneity among Brucella species. This review establishes a “Virulence-Metabolism-Temporal and Spatial” (VMT) model and proposes a Virulence Index (VI) formula to systematically compare the biological characteristics and host interaction mechanisms of four pathogenic Brucella species: B. melitensis, B. abortus, B. suis, and B. canis. Our analysis reveals that these species represent an evolutionary continuum from high virulence with acute dissemination to low virulence with tissue localization. B. melitensis achieves deep immune stealth and triggers systemic spread through its ultra-efficient Type IV Secretion System (T4SS), specific lipid A modifications, and potent apoptosis inhibition. B. suis specifically targets bone marrow and induces bone destruction via acid-inducible T4SS activation and iron metabolic hijacking. B. abortus elicits partial autophagic clearance due to insufficient T4SS efficiency, resulting in self-limiting infections. B. canis provokes intense inflammatory responses through its rough lipopolysaccharide (LPS) and exhibits defective T4SS function, precluding persistent infection establishment. The VMT model elucidates the causal chain linking molecular characteristics to cellular interactions and clinical phenotypes, demonstrating that virulence depends on the precise balance between immune evasion efficiency and host cell fate regulation. These findings provide a theoretical foundation for species-specific diagnosis, stratified therapeutics, and One Health-based precision prevention and control of brucellosis.