Critical Reviews in Microbiology最新文献

This review discusses the chemical properties, synthesis and detection, and biological functions of a molecular group of cis-2-unsaturated fatty acids, containing fatty acid carbon chains of various lengths and cis double-bond configurations, known as the diffusible signaling factor family (DSFF). Early postulation of the conserved nature of the DSFF among Gram-negative bacteria have now been challenged by the latest evidences that unraveled their presence in a various other distinct microorganisms. Over the last decade, a significant depth and breadth of understanding has been made on the multifaceted functions of DSFFs among bacteria, and their interactions with evolutionarily divergent fungi, plants insects and small animals. While the knowledge of the chemical nature and functions of DSFF within microbial systems is still developing, DSFF molecules such as BDSF, DSF, and SDSF have been found to modulate microbial virulence, cell adhesion, biofilm formation and dispersion, cell motility, and antimicrobial tolerance. Given their capacity to influence microbial ecosystems and the rapid emergence of novel DSFF-like molecules, it is critical to identify the full spectrum of DSFF members and to better understand the functions of this complex messenger system as they offer significant potential to be exploited in the development of new therapeutic strategies to combat the rising global healthcare threat of antimicrobial resistance. This narrative review therefore provides a broad picture of the DSFF quorum sensing with a core foundation built from seminal literature while highlighting the latest developments in the field.

Almost all bacteria have peptidoglycan (PG) components that are essential for virulence and are absent in humans, making them a top-priority target for antibiotics and vaccines. The rise of multidrug-resistant bacteria (MRB) necessitates urgent expansion of our arsenal of inhibitors targeting the PG cell wall. This review addresses our understanding of PG biosynthesis and recycling processes, emphasizing the need to identify novel target proteins and redesign existing PG-targeted antimicrobial peptides. Building on our understanding of cell wall biochemistry and biogenesis derived from Escherichia coli, we also aim to compare and elucidate the cell wall processes in other pathogens, such as Acinetobacter baumannii and Salmonella Typhimurium, where knowledge remains incomplete. We cover in detail the distinct roles of PG-related proteins in Gram-negative bacteria, strategies to block PG biosynthesis/recycling pathways, and their potential as novel antibiotic targets to address the growing challenge of antibiotic resistance. Finally, we review the application of rigorous immuno-informatics analysis and several immune filters to construct epitope-specific vaccines displaying PG-related proteins on the surface of outer membrane vesicles (OMVs), aiming to combat MRB proliferation.

Helicobacter pylori is globally recognized for its role in chronic gastritis, peptic ulcer disease, and gastric cancer. Yet despite decades of research and standardized eradication protocols, treatment failures and disease recurrence remain frustratingly common. While antibiotic resistance has been a central focus, emerging data suggest that H. pylori employ additional, underappreciated survival strategies that extend its pathogenic potential beyond the stomach. This review redefines H. pylori as a versatile pathogen capable of persisting through underappreciated survival strategies: the coccoid viable but non-culturable (VBNC) state, intracellular survival within yeast cells, and the release of outer membrane vesicles (OMVs). Each of these forms confers unique advantages: coccoid cells withstand environmental stress and evade standard diagnostics; yeast-harbored H. pylori may resist antibiotics, enable vertical transmission, and serve as long-term reservoirs; and OMVs can traffic toxins like VacA and CagA to distant tissues, triggering inflammation, apoptosis, and barrier dysfunction without bacterial contact. This review proposes that these alternative forms are not incidental anomalies, but integral to H. pylori's persistence, dissemination, and disease spectrum, including potential extra-gastric effects. Recognizing and targeting these hidden states may hold the key to improved diagnostics, more durable eradication, and a deeper understanding of one of medicine's most enduring pathogens.

The complex interaction between Aspergillus and Bacillus has been gaining attention with the evolution of their co-culture applications. Information reported on this interaction from different points of view including both synergistic and antagonistic mechanisms necessitates a review for better understanding. This review focuses on the interaction, biofilm formation, and the diverse biotechnological applications of Aspergillus and Bacillus, giving special attention to Aspergillus niger and Bacillus subtilis. The review demonstrates that co-cultivation of Aspergillus and Bacillus exhibits significant transcriptional changes, impacting metabolism and secondary metabolite production in both organisms. Signaling from living fungal hyphae, EPS production, TasA fibrils, and regulators like Spo0A are essential in forming biofilm communities. Nutrient availability and pH levels, species type, and mutations in EPS-producing genes may also influence whether Bacillus will act antagonistically or synergistically with Aspergillus. This dual-nature complex interaction activates silent genes synthesizing novel compounds mainly with antifungal and medicinal properties, showcasing its potential for diverse applications in various fields such as agriculture and crop protection, bioremediation, environmental biotechnology, food science and fermentation, industrial biotechnology, and medical biotechnology and health. The use of Aspergillus and Bacillus species has evolved from simple monoculture applications to more sophisticated co-cultures and has been trending toward their synergy and metabolic optimization.

Bacteria-mediated tumor treatment (BMTT) has recently garnered significant attention as a promising avenue in tumor treatment. Despite the application of various strains in animal models and clinical trials, the effectiveness of BMTT has been hindered by its toxicity and inefficiency. In recent years, it has been explored that applying the biological effects of ultrasound could further improve the precision and effectiveness of BMTT. This review briefly introduces the challenges of BMTT and summarizes how the biological effects of ultrasound improve the efficacy and safety of BMTT in strategies involving genetic engineering, visualization and targeted delivery. The potential application and limitations of ultrasound in advancing BMTT controllable strategies are also discussed.

The growing demand for nanomedicine and its potentially diverse biological function required the investigation of raw materials for fabricating the nanomaterial. Current developments have emphasized the implementation of green chemistry to develop metal-oxide and metal nanoparticles. Endophytic fungi have emerged as a potential reservoir of bioactive compounds exemplified by unique structures and influential antibacterial properties. Over the past decade, substantial progress has been achieved in uncovering and profiling these valuable antibacterial compounds. These endophytic fungi-derived bioactive chemicals have diverse applications in various biological properties. Nanoparticle synthesis from materials derived from endophytic fungi, be it whole extracts or pure components, owing to their accessibility, cost-effectiveness in fabrication, material-tissue compatibility, and modest cytotoxicity toward higher organism cells. Nanoparticles from endophytic fungi have been utilized to treat various diseases, including those caused by bacterial, viral, and fungal pathogens. The present review provides a comprehensive discussion of the mechanistic insight into the synthesis and application of endophytic fungi-bioinspired nanoparticles as potential therapeutic agents to control microbial infection. The underlying action mechanism involved in the antimicrobial action of the nanoparticles has also been discussed. The discussion highlights various attributes of nanoparticles that may significantly benefit future researchers as potential therapeutic agents to control microbial infection.

Heteroresistance of bacteria refers to the presence of bacterial subgroups with different antibiotic sensitivity in the same strain, affecting the bacterial eradication effect. In recent years, heteroresistance has posed significant challenges to H. pylori eradication failure, while little is known about heteroresistance to H. pylori. Facing the current growing heteroresistance and declining eradication rates of H. pylori, it is necessary to comprehensively understand the epidemiology of heteroresistance as well as detection methods, and elucidate the relevant resistance mechanisms to find a more ideal precision treatment. In this study, we systematically review the current studies of H. pylori heteroresistance and summarize the detection methods and possible heteroresistance mechanisms. In brief, it is highly significant to further strengthen the general understanding for H. pylori heteroresistance. Accordingly, it is necessary to conduct extensive clinical studies on the incidence of H. pylori heteroresistance and to refine the clinical definition of H. pylori heteroresistance. The development of accurate and standardized detection technology is the key to heteroresistance diagnosis. In addition, we strongly advocate to further study the heteroresistance mechanism of H. pylori in vivo and in vitro, which will advance the development of more effective treatment strategies and facilitate the refinement of clinical guidelines.

Many consider the gut microbiota an organ of the human body; although the view is controversial, its effect on overall human health cannot be denied. The mucosal gut bacteria are physiologically distinct from those inhabiting the gut lumen or fecal material. They have a central role in regulating the intestinal mucosal barrier properties, protecting against intestinal inflammation. The human gut-associated bifidobacteria can form robust biofilms that can form distinct microcolonies with colonization patterns unique to a species or across several species. The species-specific spatial distribution hints at an undeciphered fitness advantage in the host gut milieu. The antipathogenicity of indigenous Bifidobacterium strains represents a promising therapeutic strategy against pathogenic biofilms that resists existing medical therapies. Harnessing their biofilm phenotype constitutes a central premise of the fourth-generation probiotics, which can better benefit the human gut. The beneficial bacteria could be harnessed to fight infectious diseases in developing countries such as Pakistan, plagued by food insecurity. This evidence prima facie suggests that further studies are needed to test the in vivo potential of these probiotic candidates as live-biotherapeutic agents.

Antimicrobial resistance (AMR) poses a significant public health threat, with emerging and novel forms of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) potentially crossing international borders and challenging the global health systems. The rate of development of antibiotic resistance surpasses the development of new antibiotics. Consequently, there is a growing threat of bacteria acquiring resistance even to newer antibiotics further complicating the treatment of bacterial infections. Horizontal gene transfer (HGT) is the key mechanism for the spread of antibiotic resistance in bacteria through the processes of conjugation, transformation, and transduction. Several compounds, other than antibiotics, have also been shown to promote HGT of ARGs. Given the crucial role of HGT in the dissemination of ARGs, inhibition of HGT is a key strategy to mitigate AMR. Therefore, this review explores the contribution of HGT in bacterial evolution, identifies specific hotspots andhighlights the role of HGT inhibitors in impeding the spread of ARGs. By specifically focusing on the HGT mechanism and its inhibition, these inhibitors offer a highly promising approach to combating AMR.

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS), affect millions of people worldwide. While considerable progress has been made to elucidate the pathogenesis of these diseases in recent years, their specific mechanisms remain largely unknown. Many research study results have proven a certain association between the oral microbiome and neurodegenerative diseases. This review focuses on the relationship between the oral microbiome and neurodegenerative diseases, with a particular focus on the mechanisms of neuroinflammation.