Critical Reviews in Microbiology最新文献

Efflux-mediated resistance is a critical mechanism by which bacterial pathogens evade antibiotic treatment, posing significant challenges to effective infection management. As the first line of defence mechanism in bacteria, efflux pumps actively expel antibiotics, contributing to multidrug resistance. Recent advances in nanotechnology offer promising solutions, with nanobiotics emerging as a novel approach to combating efflux-mediated resistance. Nanobiotics are engineered nanoscale materials with antibacterial properties. They can be designed to inhibit efflux pump function, enhance drug accumulation, and disrupt bacterial cell membranes, thereby overcoming traditional resistance mechanisms. Nanobiotics can easily fuze with the bacterial cell wall and facilitate the release of antibiotics into the cytoplasm. This review provides an overview of efflux-mediated resistance mechanisms, highlights recent nanotechnology developments to design and formulate nanobiotics, and examines their potential to inhibit efflux pumps in multidrug-resistant bacterial strains. By targeting efflux systems, nanobiotics offer a potent and innovative approach to restoring the efficacy of conventional antibiotics and advancing the treatment of multidrug-resistant bacterial infections.

Novel antibacterial agents are critically needed in light of the constant menace posed by bacterial infections and subsequent emergence of antibiotic-resistant strains. Quality of life has been improved remarkably through antibiotics that have fought microbial pathogens. . Luteolin has shown effectiveness against both gram-positive and gram negative bacteria. Luteolin and its derivatives, as novel phytochemical antimicrobial agents, exhibit activity against both Gram-positive and Gram-negative bacteria . Luteolin target bacteria by disrupting their cell membranes, inhibiting nucleic acid synthesis, and interfering with key enzymes. It also blocks quorum sensing and biofilm formation, crucial for bacterial virulence and resistance. Luteolin, despite its therapeutic potential, has limited clinical use due to poor water solubility and low bioavailability, leading to reduced absorption and rapid metabolism in the body. To address these issues, researchers are exploring advanced formulations like nanoparticles and liposomes to improve its solubility and effectiveness. Recent formulation advancements aim to enhance luteolin's delivery and efficacy as an antibacterial agent. However, in-depth in vivo studies are essential to unlock its full therapeutic potential for clinical use. This review highlights luteolin's antibacterial capabilities, usage challenges, and recent progress, stressing the importance of further research to fully leverage its benefits.

Industrialization marked a significant turning point that impacted the global climate at an unprecedented scale. Oceans, covering 71% of the surface of Earth, play a pivotal role in regulating climate change factors, serving as essential components of planetary processes. In these oceanic ecosystems, marine bacteria are intricately involved in regulating various biogeochemical cycles that are crucial to climate regulation and ecosystem functioning. However, the ongoing climatic changes pose significant challenges to marine bacteria and their associated processes. In the Anthropocene epoch, the interaction between anthropogenic pollutants and climatic stressors further amplifies their impact on marine bacteria across diverse ecological niches and their resilience mechanisms. It delves into the interactive effects of anthropogenic pollutants with climatic stressors on bacteria, particularly emphasizing on organic pollutants, heavy metals, and microplastics. The review entails the impact and resilience mechanisms of marine bacteria in response to climatic stressors. The current trajectory of climatic changes highlights the urgent need for concerted global action to mitigate greenhouse gas emissions and adapt to the inevitable impacts of climate change. In this context, various strategies employing marine bacteria in mitigating climate change for a sustainable future have also been discussed.

Streptococcus mutans is a caries-associated bacterium with the ability to adhere to the surface of oral tissues and promote biofilm formation. For this purpose, S. mutans expresses a range of specialized surface adhesins, among which collagen-binding proteins (CBPs) have demonstrated an important function regarding attachment to dentin, bacterial coaggregation, and extracellular matrix invasion. Understanding the mechanobiological behavior of CBPs, particularly their interaction with collagens during the process of bacterial adhesion, is crucial for developing novel strategies to prevent biofilm formation in oral and remote tissues. Therefore, this review summarizes recent evidence regarding the main mechanical properties of the relevant S. mutans CBPs SpaP, WapA, Cnm, and Cbm, and how their mechanobiological and adhesive characteristics play an important role in their virulence toward the host. Particularly, we will focus on how state-of-the-art interdisciplinary approaches such as atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) and single-cell force spectroscopy (SCFS) have been employed to characterize S. mutans and CBP attachment to collagen substrates and mechanical behavior in real-time and under physiological conditions. Altogether, the potential use of AFM SMFS and SCFS to explore novel anti-biofilm molecules against S. mutans remains an exciting possibility for the development of caries-preventive treatments in the future.

Porphyrins, their derivatives, and metal ion complexes - particularly copper-substituted forms such as Cu-Chl, Cu-Chln, and Na-Cu-Chln - are increasingly recognized for their broad-spectrum antimicrobial properties. However, in the context of terminological and trivial confusions in food chemistry and pharmaceuticals, data on the chemical properties and biological activity of porphyrins remains fragmented and lacks comprehensive systematization. This review adopts a cross-disciplinary mapping approach to clarify the chemical structures, nomenclature, antimicrobial properties, and the presented mechanistic insights of porphyrins and their derivatives, highlighting their significance in both the food and pharmaceutical industries. As a result of the mapping systematization, porphyrins have been remarked as current and potential antimicrobial agents, with a specific emphasis on the compounds such as Cu-Chl, Cu-Chln, and Na-Cu-Chln. Copper complexation has been shown to enhance biological activity while maintaining low toxicity profiles. Emphasis is placed on Cu-Chl, Cu-Chln, and Na-Cu-Chln, which demonstrate promising properties and applications in nutraceuticals and therapeutics. Their bactericidal properties, which resulted in combating antibiotic-resistant infection-causative pathogens, are particularly interesting, especially in the era of addressing global challenges such as antibiotic resistance. This conceptual review remarks on the critical gaps in current knowledge and accentuates the need for systematic studies to optimize the clinical and industrial applications of porphyrins.

Quorum sensing (QS) is a bacterial communication method closely linked with population density and regulates biofilm formation and the secretion of virulence factors through the release, recognition, and prompt response to small molecule signals. At low cell density, each bacterium produces a low concentration of QS signals that diffuse or are actively transported into the external environment. The accumulated QS signals in the external environment reach a threshold concentration when the bacterial population attains a certain density, enabling effective recognition and interaction of bacterial QS signals with their receptors. This leads to coordinated gene expression and various biological activities across the bacterial population. Targeting the QS system presents a promising strategy to hinder biofilm formation and virulence factor secretion, providing a potential approach to control bacterial growth and reproduction. This study aims to analyze the intercellular mechanisms of quorum quenching (QQ), which focuses on disrupting bacterial signal molecules to keep their concentration below the threshold and preventing the expression of specific pathogenic factors. The applications of QQ in different fields are also reviewed, underscoring its potential as a novel treatment for bacterial infections.

Vaccination plays a critical role in public health by reducing the incidence and prevalence of infectious diseases. The efficacy of a vaccine has numerous determinants, which include age, sex, genetics, environment, geographic location, nutritional status, maternal antibodies, and prior exposure to pathogens. However, little is known about the role of gut microbiome in vaccine efficacy and how it can be targeted through dietary interventions to improve immunological responses. Unveiling this link is imperative, particularly in the post-pandemic world, considering impaired COVID-19 vaccine response observed in dysbiotic individuals. Therefore, this article aims to comprehensively review how diet and probiotics can modulate gut microbiome composition, which is linked to vaccine efficacy. Dietary fiber and polyphenolic compounds derived from plant-based foods improve gut microbial diversity and vaccine efficacy by promoting the growth of short-chain fatty acids-producing microbes. On the other hand, animal-based foods have mixed effects - whey protein and fish oil promote gut eubiosis and vaccine efficacy. In contrast, lard and red meat have adverse effects. Studies further indicate that probiotic supplements exert varied effects, mostly strain and dosage-specific. Interlinking diet, microbiome, probiotics, and vaccines will reveal opportunities for newer research on diet-induced microbiome-manipulated precision vaccination strategies against infectious diseases.

Inflammatory bowel disease (IBD) refers to a group of chronic inflammatory disorders impacting the gastrointestinal (GI) tract. It represents a significant public health challenge due to its rising global incidence and substantial impact on patients' quality of life. Emerging research suggests a pivotal role of the human microbiome in IBD pathogenesis. Bacteriophages, integral components of the human microbiome, are indicated to influence the disease onset, progression, and therapeutic strategies. Here, we review the effect of bacteriophages on the pathogenesis of IBD and, more specifically, on the gut bacteria, the systemic immunity, and the susceptibility genes. Additionally, we explore the potential therapeutic use of the bacteriophages to modify gut microbiota and improve the health outcomes of IBD patients. This review highlights the potential of therapeutic bacteriophages in regulating gut microbiota and modulating the immune response to improve health outcomes in IBD patients. Future studies on personalized bacteriophage therapy and its integration into clinical practice could advance treatment strategies for IBD.

Biofilms are one of the most successful modes of life in the biosphere. In these assemblages, bacteria usually display higher resistance to environmental stressors, thus making their removal through the use of conventional approaches significantly more difficult. Currently, biofilms are one of the major challenges in healthcare settings, often resulting in higher mortality and morbidity rates. Therefore, seeking alternative approaches to manage biofilm-related infections is important. In the last decades, marine microbiomes have been increasingly harnessed as sources of molecules with wide-ranging applications in both the biomedical and pharmaceutical sectors. This review focuses on enzymes as potential antibiofilm agents, more specifically those derived from marine prokaryotes. An overview of the recent findings regarding four main classes of biofilm-disrupting enzymes and their respective marine microbial producers, namely nucleases, dextranases, alginate lyases, and peptidases is provided. Key biochemical and activity-related features from the current literature are presented to showcase the potential of these biocatalysts for biofilm control and prevention. Future research directions are also discussed, highlighting factors and strategies for successful prospecting of antibiofilm enzymes from marine microbiomes. By offering a snapshot of this infant but promising field, this review evidences the marine environment as a fruitful biocatalytic reservoirs of antibiofilm agents.

Bacterial-cell surface display represents a novel field of protein engineering, which is grounds for presenting recombinant proteins or peptides on the surface of host cells. This technique is primarily used for endowing cellular activity on the host cells and enables several biotechnological applications. In this review, we comprehensively summarize the speciality of bacterial surface display, specifically in gram-positive and gram-negative organisms and then we depict the practical cases to show the importance of bacterial cell surface display in biomedicine and bioremediation domains. We manifest that among other display systems such as phages and ribosomes, the cell surface display using bacterial cells can be used to avoid the loss of combinatorial protein libraries and also open the possibility of isolating target-binding variants using high-throughput selection platforms. Thus, it is becoming a robust tool for functionalizing microbes to serve as a potential implement for various bioengineering purposes.