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Topic Review
Escherichia coli O157
Escherichia coli O157:H7 (O157) are noninvasive and weak biofilm producers; however, a subset of O157 are exceptions. O157 ATCC 43895 forms biofilms and invades epithelial cells. Tn5 mutagenesis identified mutation insertions that map within the curli csgB fimbriae locus to be responsible for both phenotypes. Screening of O157 strains for biofilm formation and cell invasion identify a bovine and a clinical isolate with those characteristics. A single base pair A to T transversion, intergenic to the curli divergent operons csgDEFG and csgBAC, is present only in biofilm-producing and invasive strains. Using site-directed mutagenesis, this single base change was introduced into two curli-negative/noninvasive O157 strains and modified strains to form biofilms, produce curli, and gain invasive capability. Transmission electron microscopy (EM) and immuno-EM confirmed curli fibers. EM of bovine epithelial cells (MAC-T) co-cultured with curli-expressing O157 show intracellular bacteria. The role of curli in O157 persistence in cattle was examined by challenging cattle with curli-positive and -negative O157 and comparing carriage. The duration of bovine colonization with the O157 curli-negative mutant was shorter than its curli-positive isogenic parent. These findings definitively demonstrate that a single base pair stably confers biofilm formation, epithelial cell invasion, and persistence in cattle. 
  • 1.1K
  • 30 Oct 2020
Topic Review
Helicobacter Pylori Survival Tactics
Helicobacter pylori is well established as a causative agent for gastritis, peptic ulcer, and gastric cancer. Armed with various inimitable virulence factors, this Gram-negative bacterium is one of few microorganisms that is capable of circumventing the harsh environment of the stomach. The unique spiral structure, flagella, and outer membrane proteins accelerate H. pylori movement within the viscous gastric mucosal layers while facilitating its attachment to the epithelial cells. Furthermore, secretion of urease from H. pylori eases the acidic pH within the stomach, thus creating a niche for bacteria survival and replication. Upon gaining a foothold in the gastric epithelial lining, bacterial protein CagA is injected into host cells through a type IV secretion system (T4SS), which together with VacA, damage the gastric epithelial cells.
  • 1.1K
  • 29 Mar 2022
Topic Review
The Influence of Specific Microbial Species on Diabetes
Diabetes mellitus (DM) is a metabolic disorder with an alarming incidence rate and a considerable burden on the patient’s life and health care providers. An increase in blood glucose level and insulin resistance characterizes it. Internal and external factors such as urbanization, obesity, and genetic mutations could increase the risk of DM. Microbes in the gut influence overall health through immunity and nutrition. More studies have been conducted to evaluate and estimate the role of the gut microbiome in diabetes development, progression, and management. 
  • 1.1K
  • 15 May 2023
Topic Review
Entomopathogenic Microorganisms in Animals Protection
The control of ectoparasites requests the development of novel strategies and, among them, the use of entomopathogenic microorganisms appears as a promising tool to achieve an eco-friendly approach. 
  • 1.1K
  • 29 Jun 2021
Topic Review
Cigarette Smoking and Human Gut Microbiota
The intestinal microbiota is a crucial regulator of human health and disease because of its interactions with the immune system. Tobacco smoke also influences the human ecosystem with implications for disease development. This entry aims to analyze the available evidence, until June 2021, on the relationship between traditional and/or electronic cigarette smoking and intestinal microbiota in healthy human adults.
  • 1.1K
  • 07 Mar 2022
Topic Review
Gut Microbiota on Liver Diseases
The gut–liver axis plays important roles in both the maintenance of a healthy liver and the pathogenesis of liver diseases, where the gut microbiota acts as a major determinant of this relationship. Gut bacteria-derived metabolites and cellular components are key molecules that affect the function of the liver and modulate the pathology of liver diseases. Accumulating evidence showed that gut microbiota produces a myriad of molecules, including lipopolysaccharide, lipoteichoic acid, peptidoglycan, and DNA, as well as short-chain fatty acids, bile acids, trimethylamine, and indole derivatives. The translocation of these components to the liver exerts beneficial or pathogenic effects by interacting with liver immune cells. This is a bidirectional relationship.
  • 1.1K
  • 26 Dec 2020
Topic Review
CRISPR-Cas Systems
The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPR-associated cas) systems constitute the adaptive immune system in prokaryotes, which provides resistance against bacteriophages and invasive genetic elements. The landscape of applications in bacteria and eukaryotes relies on a few Cas effector proteins that have been characterized in detail. However, there is a lack of comprehensive studies on naturally occurring CRISPR-Cas systems in beneficial bacteria, such as human gut commensal Bifidobacterium species.
  • 1.1K
  • 28 Oct 2020
Topic Review
Immunogenic Proteins of Group B Streptococcus
Streptococcus agalactiae (Group B Streptococcus, GBS) is an opportunistic pathogen, which asymptomatically colonizes the gastrointestinal and genitourinary tract of up to one third of healthy adults. Nevertheless, GBS carriage in pregnant women may lead to several health issues in newborns causing life threatening infection, such as sepsis, pneumonia or meningitis. Recommended GBS screening in pregnant women significantly reduced morbidity and mortality in infants. Nevertheless, intrapartum antibiotic prophylaxis, recommended following the detection of carriage or in case of lack of a carriage test result for pregnant women who demonstrate certain risk factors, led to the expansion of the adverse phenomenon of bacterial resistance to antibiotics.
  • 1.1K
  • 05 Jan 2022
Topic Review
Secondary Metabolites Produced by Penicillium roqueforti
Filamentous fungi are an important source of natural products. The mold Penicillium roqueforti, which is well-known for being responsible for the characteristic texture, blue-green spots, and aroma of the so-called blue-veined cheeses (French Bleu, Roquefort, Gorgonzola, Stilton, Cabrales, and Valdeón, among others), is able to synthesize different secondary metabolites, including andrastins and mycophenolic acid, as well as several mycotoxins, such as Roquefortines C and D, PR-toxin and eremofortins, Isofumigaclavines A and B, festuclavine, and Annullatins D and F.
  • 1.1K
  • 27 Apr 2023
Topic Review
SARS-CoV-2 and Oral Inflammatory Diseases
The oral cavity is a niche for diverse microbes, including viruses. Members of the Herpesviridae family, comprised of dsDNA viruses, as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an ssRNA virus, are among the most prevalent viruses infecting the oral cavity, and they exhibit clinical manifestations unique to oral tissues. Herpesviruses and SARS-CoV-2 are individually associated with oral inflammatory diseases, particularly periodontitis, peri-implantitis, and endodontic disease.
  • 1.1K
  • 15 Jan 2024
Topic Review
Membrane Vesicles Derived from Gut Microbiota
Multidrug-resistant (MDR) superbugs can breach the blood–brain barrier (BBB), leading to a continuous barrage of pro-inflammatory modulators and induction of severe infection-related pathologies, including meningitis and brain abscess. Both broad-spectrum or species-specific antibiotics (β-lactamase inhibitors, polymyxins, vancomycin, meropenem, plazomicin, and sarecycline) and biocompatible poly (lactic-co-glycolic acid) (PLGA) nanoparticles have been used to treat these infections. However, new therapeutic platforms with a broad impact that do not exert off-target deleterious effects are needed. Membrane vesicles or extracellular vesicles (EVs) are lipid bilayer-enclosed particles with therapeutic potential owing to their ability to circumvent BBB constraints. Bacteria-derived EVs (bEVs) from gut microbiota are efficient transporters that can penetrate the central nervous system. In fact, bEVs can be remodeled via surface modification and CRISPR/Cas editing and, thus, represent a novel platform for conferring protection against infections breaching the BBB.
  • 1.1K
  • 09 Dec 2022
Topic Review
Regulatory RNAs in Communication
In eukaryotes, microRNAs (miRNAs) have roles in development, homeostasis, disease and the immune response. Recent work has shown that plant and mammalian miRNAs also mediate cross-kingdom and cross-domain communications, but these studies remain controversial and are lacking critical mechanistic explanations. However, there are several conserved features and homologous components in the distinct Regulatory RNA pathways in eukaryotes and bacteria that could explain how eukaryotic miRNAs could function in such cross-domain communications.
  • 1.1K
  • 09 Jan 2021
Topic Review
Resistome, Mobilome and Nichome
There are three concepts linked to the growing resistance to antibiotics, namely (i) the Resistome, which refers to the collection of bacterial genes that confer resistance to antibiotics, (ii) the Mobilome, which includes all the mobile genetic elements that participate in the spreading of antibiotic resistance among bacteria by horizontal gene transfer processes, and (iii) the Nichome, which refers to the set of genes that are expressed when bacteria try to colonize new niches. 
  • 1.1K
  • 24 Oct 2023
Topic Review
Metabolic Engineering of Yeast for Bioethanol Production
Increased human population and the rapid decline of fossil fuels resulted in a global tendency to look for alternative fuel sources. Ethanol has been the primary fossil fuel alternative due to its low carbon emission rates, high octane content and comparatively facile microbial production processes. As a well-known platform microorganism and native ethanol producer, baker’s yeast Saccharomyces cerevisiae has been the primary subject of interest for both academic and industrial perspectives in terms of enhanced ethanol production processes. Metabolic engineering strategies have been primarily adopted for direct manipulation of genes of interest responsible in mainstreams of ethanol metabolism. To overcome limitations of rational metabolic engineering, an alternative bottom-up strategy called inverse metabolic engineering has been widely used. In this context, evolutionary engineering, also known as adaptive laboratory evolution (ALE), which is based on random mutagenesis and systematic selection, is a powerful strategy to improve bioethanol production of S. cerevisiae. Metabolic and evolutionary engineering strategies are intertwined and many metabolically engineered strains for bioethanol production can be further improved by powerful evolutionary engineering strategies as well as the recent advancements in directed genome evolution, including CRISPR-Cas9 technology.
  • 1.1K
  • 16 Oct 2023
Topic Review
Xenorhabdus spp.
Xenorhabdus bacteria, as pesticidal symbionts of the entomopathogenic nematodes Steinernema species, can contribute to this solution with a treasure trove of insecticidal compounds and an ability to suppress a variety of plant pathogens. As many challenges face sound exploitation of plant–phytonematode interactions, a full useful spectrum of such interactions should address nematicidal activity of Xenorhabdus. Steinernema–Xenorhabdus complex or Xenorhabdus individually should be involved in mechanisms underlying the favorable side of plant–nematode interactions in emerging cropping systems. Using Xenorhabdus bacteria should earnestly be harnessed to control not only phytonematodes, but also other plant pests and pathogens within integrated pest management plans. 
  • 1.1K
  • 24 Nov 2022
Topic Review
Gut Microbiota in Primary Immunodeficiencies
Inborn errors of immunity (IEI) are a group of disorders that are mostly caused by genetic mutations affecting immune host defense and immune regulation. Although IEI present with a wide spectrum of clinical features, in about one third of them various degrees of gastrointestinal (GI) involvement have been described and for some IEI the GI manifestations represent the main and peculiar clinical feature. The microbiome plays critical roles in the education and function of the host’s innate and adaptive immune system, and imbalances in microbiota-immunity interactions can contribute to intestinal pathogenesis. Microbial dysbiosis combined to the impairment of immunosurveillance and immune dysfunction in IEI, may favor mucosal permeability and lead to inflammation. Here we review how immune homeostasis between commensals and the host is established in the gut, and how these mechanisms can be disrupted in the context of primary immunodeficiencies. Additionally, we highlight key aspects of the first studies on gut microbiome in patients affected by IEI and discuss how gut microbiome could be harnessed as a therapeutic approach in these diseases.
  • 1.1K
  • 16 Feb 2021
Topic Review
Severe Acute Respiratory Syndrome-related Coronavirus
Severe acute respiratory syndrome–related coronavirus (SARS-CoV or SARSr-CoV)[note 1] is a species of coronavirus that infects humans, bats and certain other mammals. It is an enveloped positive-sense single-stranded RNA virus that enters its host cell by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. It is a member of the genus Betacoronavirus and subgenus Sarbecovirus. Two strains of the virus have caused outbreaks of severe respiratory diseases in humans: severe acute respiratory syndrome coronavirus (SARS-CoV or SARS-CoV-1), which caused the 2002–2004 outbreak of severe acute respiratory syndrome (SARS), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is causing the 2019–20 pandemic of coronavirus disease 2019 (COVID-19). There are hundreds of other strains of SARS-CoV, all of which are only known to infect non-human species: bats are a major reservoir of many strains of SARS-related coronaviruses, and several strains have been identified in palm civets, which were likely ancestors of SARS-CoV. The SARS-related coronavirus was one of several viruses identified by the World Health Organization (WHO) in 2016 as a likely cause of a future epidemic in a new plan developed after the Ebola epidemic for urgent research and development before and during an epidemic towards diagnostic tests, vaccines and medicines. The prediction came to pass with the COVID-19 pandemic.
  • 1.1K
  • 12 Oct 2022
Topic Review
Managing Oral Health in Context of Antimicrobial Resistance
The oral microbiome plays a major role in shaping oral health/disease state; thus, a main challenge for dental practitioners is to preserve or restore a balanced oral microbiome. Nonetheless, when pathogenic microorganisms install in the oral cavity and are incorporated into the oral biofilm, oral infections, such as gingivitis, dental caries, periodontitis, and peri-implantitis, can arise. Several prophylactic and treatment approaches are available nowadays, but most of them have been antibiotic-based. Given the actual context of antimicrobial resistance (AMR), antibiotic stewardship in dentistry would be a beneficial approach to optimize and avoid inappropriate or even unnecessary antibiotic use, representing a step towards precision medicine. 
  • 1.1K
  • 23 Dec 2022
Topic Review
Robert Koch
Robert Heinrich Hermann Koch was a pioneering German physician and microbiologist whose groundbreaking work laid the foundations for modern bacteriology. He is most renowned for discovering the causative agents of tuberculosis, cholera, and anthrax, and for formulating the postulates that define pathogenic organisms in infectious diseases.
  • 1.1K
  • 14 Jul 2025
Topic Review Peer Reviewed
Effect of Probiotics on Host-Microbial Crosstalk: A Review on Strategies to Combat Diversified Strain of Coronavirus
The scare of the ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), does not seem to fade away, while there is a constant emergence of novel deadly variants including Alpha, Beta, Gamma, Delta and Omicron. Until now, it has claimed approximately 276,436,619 infections, and the number of deaths surpluses to 5,374,744 all over the world. While saving the life has been a priority during the ongoing SARS-CoV-2 pandemic, the post-infection healing and getting back to normalcy has been undermined. Improving general health conditions and immunity with nutritional adequacy is currently of precedence for the government as well as frontline health workers to prevent and assuage infections. Exploring the role of probiotics and prebiotics in managing the after-effects of a viral outbreak could be of great significance, considering the emergence of new variants every now and then. To enhance human immunity, the recent evidence on the connection between gut microbiota and the broad spectrum of the clinical COVID-19 disease is the reason to look at the benefits of probiotics in improving health conditions. This review aims to sketch out the prospective role of probiotics and prebiotics in improving the standard of health in common people.
  • 1.1K
  • 10 Mar 2023
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