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Topic Review
Chasing the Elusive Luciferin
Regarding dinoflagellates, the mechanisms related to the bioluminescent phenomenon have been well studied; however, at present, some points that remain unknown still persist. That is the case of luciferin biosynthesis, which has been reported to be an intricate process with several metabolic pathways involved. In the context of this controversial scenario, various hypotheses about the biosynthesis of luciferin in dinoflagellates are presented.
  • 1.7K
  • 10 Dec 2020
Topic Review
Lignans
This entry focuses on lignans, a non-flavonoid polyphenolic class found in plant foods for human nutrition, recently studied as potential modulators of the gut-brain axis. In particular, gut bacterial metabolism is able to convert dietary lignans into therapeutically relevant polyphenols (i.e., enterolignans), such as enterolactone and enterodiol. Enterolignans are characterized by various biologic activities, including tissue-specific estrogen receptor activation, together with anti-inflammatory and apoptotic effects. The variability in enterolignans production by the gut microbiota is strictly related to both bioaccessibility and bioavailability of parent lignans through the entire gastrointestinal tract. 
  • 1.7K
  • 06 Jan 2021
Topic Review
Human Cytomegalovirus
Human cytomegalovirus (HCMV) expresses a variety of viral regulatory proteins that undergo close interaction with host factors including viral-cellular multiprotein complexes. The HCMV protein kinase pUL97 represents a viral CDK ortholog (vCDK) that determines the efficiency of HCMV replication via phosphorylation of viral and cellular substrates. A hierarchy of functional importance of individual pUL97-mediated phosphorylation events has been discussed, however, the most pronounced pUL97-dependent phenotype could be assigned to viral nuclear egress, as illustrated by genetic ORF-UL97 deletion or pharmacological pUL97 inhibition. Despite earlier data pointing to a cyclin-independent functionality, experimental evidence increasingly emphasized the role of pUL97-cyclin complexes. Consequently, the knowledge about pUL97 involvement in host interaction, viral nuclear egress and additional replicative steps led to the postulation of pUL97 as an antiviral target. Indeed, validation experiments in vitro and in vivo confirmed the sustainability of this approach. Consequently, current investigations of pUL97 in antiviral treatment go beyond the known pUL97-mediated ganciclovir prodrug activation and henceforward include pUL97-specific kinase inhibitors. Among a number of interesting small molecules analyzed on experimental and preclinical stages, maribavir is presently investigated in clinical studies and, in the near future, might represent a first kinase inhibitor applied in the field of antiviral therapy.
  • 1.7K
  • 29 Oct 2020
Topic Review
Escherichia coli Shiga Toxins
Escherichia coli (EHEC) and Shigella dysenteriae serotype 1 are enterohemorrhagic bacteria that induce hemorrhagic colitis. This, in turn, may result in potentially lethal complications, such as hemolytic uremic syndrome (HUS), which is characterized by thrombocytopenia, acute renal failure, and neurological abnormalities. Both species of bacteria produce Shiga toxins (Stxs), a phage-encoded exotoxin inhibiting protein synthesis in host cells that are primarily responsible for bacterial virulence.
  • 1.7K
  • 23 Jun 2021
Topic Review
Chloroflexi (Phylum)
The Chloroflexi or Chlorobacteria are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis (green non-sulfur bacteria); and anaerobic halorespirers, which uses halogenated organics (such as the toxic chlorinated ethenes and polychlorinated biphenyls) as electron acceptors. Most bacteria, in terms of diversity, are diderms and stain gram-negative, notable exceptions being Firmicutes (low G+C gram-positives), Actinobacteria (high-G+C gram-positives) and the Deinococcus–Thermus group (gram-positive diderms with thick peptidoglycan). In contrast, the members of the phylum Chloroflexi are monoderms, but stain mostly gram-negative.
  • 1.7K
  • 21 Oct 2022
Topic Review
Application of Microbes in Pesticide Degradation
Microbes (fungal and bacterial) applications have been identified for the bio-degradation of agro-chemicals within the environment. The efficiency of microbial species to bio-degrade chemicals varies considerably. Pesticide remediation using microbes transforms harmful chemicals into nontoxic, eco-friendly, and beneficial metabolites. During pesticides decomposition, the biosorption rate for a single strain is insufficient, whereas the focus of degradation studies is rapidly turning towards microbiological consortiums, and pesticide bio-degradability is determined through pesticide components, available mechanisms, and the promiscuity of enzymes. Certain pesticides break down relatively faster than others. The slower ones are trinitrotoluene (TNT), polychlorinated biphenyl (PCBs), and pentachlorophenol (PCP). However, methomyl, pyrethroids, 1,3-dichloropropene, and atrazine can degrade faster. Axenic cultured cells are concentrated more on pesticides breakdown than microbial consortia. Earlier research has examined various microbial communities that, particularly axenic strains, may degrade chemicals quickly. During investigations, both single and a mixture of microbial strains are effective. Although axenic cells seem critical in metabolic studies, their physiology and molecular compositions are related to pesticide decomposition. The synthesis of the consortium was achieved premised on the performances of axenic colonies in pesticide degrading, and the microbial consortia became identified to have the tremendous potential.
  • 1.7K
  • 24 May 2022
Topic Review
Viral Infections and Thymus
The thymus gland is a primary lymphoid organ for T-cell development. T-cells are one of the white blood cells that play a critical role in adaptive immune response. Various viral infections can result in the disturbance of thymic functions.
  • 1.7K
  • 17 Jun 2021
Topic Review
Bacillus Species and Heavy Metals
 Heavy metals are one of the major pollutants that contribute to the escalating problem of environmental pollution, being primarily introduced in sensitive ecological habitats through industrial effluents, wastewater, as well as sewage of various industries. Microbial bioremediation, particularly the use of bacteria, has gained attention due to the feasibility and efficiency of using them in removing heavy metals from contaminated environments. Bacteria have several methods of processing heavy metals through general resistance mechanisms, biosorption, adsorption, and efflux mechanisms. Bacillus spp. are model Gram-positive bacteria that have been studied extensively for their biosorption abilities and molecular mechanisms that enable their survival as well as their ability to remove and detoxify heavy metals.
  • 1.6K
  • 09 Aug 2021
Topic Review
Biological Nitrogen Fixation
In agroecosystems, nitrogen is one of the major nutrients limiting plant growth. To meet the increased nitrogen demand in agriculture, synthetic fertilizers have been used extensively in the latter part of the twentieth century, which have led to environmental challenges such as nitrate pollution. Biological nitrogen fixation (BNF) in plants is an essential mechanism for sustainable agricultural production and healthy ecosystem functioning. BNF by legumes and associative, endosymbiotic, and endophytic nitrogen fixation in non-legumes play major roles in reducing the use of synthetic nitrogen fertilizer in agriculture, increased plant nutrient content, and soil health reclamation. 
  • 1.6K
  • 24 Nov 2021
Topic Review
Structure and Function of Microbial Lipases
Lipases or triacylglycerol acyl hydrolases (EC 3.1.1.3) are ubiquitous in all realms of life. In nature, they are mainly characterized by catalyzing the hydrolysis of triglycerides and long-chain partial glycerides, releasing fatty acids, monoglycerides and glycerol. These enzymes constitute a key link in the cellular processes related to the absorption, release and metabolism of fats, since its substrates and derivatives are the most abundant lipids in cells. On the other hand, some lipases have also been attributed functions as defense enzymes or as virulence factors.  The main aspects of the structure–function of microbial lipases, reviewed more extensively in other articles, will be summarized in a general way, but, here, emphasis will be placed on aspects to be discussed in later sections such as their immobilization and applications in reactions of interest in the production of compounds related to APIs.
  • 1.6K
  • 21 Sep 2022
Topic Review
Horizontal transfer of Resistance Genes
Emergence and rapid spread of antibiotic resistance has posed a serious threat to public health and undermined decades of progress made in the fight against bacterial infections. Plasmid-mediated horizontal tranfer of antibiotic resistance genes (ARGs) has been recognized as the most dominant dissemination pathway of ARGs in humans, animals and environmental settings. In particular, four pathways including conjugation, transformation, transduction and vesiduction account for horizontal transfer of antibiotic resistance genes. A better understanding of these pathways and underlying mechanisms would contribute to developing more effective stategies to control the prevalence of ARGs.
  • 1.6K
  • 14 Aug 2020
Topic Review Peer Reviewed
Arbuscular Mycorrhizal Fungi in Agriculture
Arbuscular mycorrhizal (AM) fungi are biotrophic symbionts forming close relationships with an estimated 80% of terrestrial plants suitable as their host. Via an established AM fungal–host relationship, soil-bound nutrients are made available to the host plant through root cortical arbuscules as the site of exchange. At these sites, photosynthetic carbohydrates are provided to the AM fungus—carbohydrates that cannot be produced by the fungus. AM fungal–host symbiosis is very sensitive to soil disturbance, for example, agricultural tillage practices can damage and reduce AM fungal abilities to interact with a host and provide plant growth-promoting properties.
  • 1.6K
  • 13 Apr 2022
Topic Review
Eye Diseases Associated with Oral Pathogens
Even before the advancement of sophisticated molecular biology techniques, eye diseases were regarded as manifestations of infections in the mouth. A few of the ancient studies interrelated the resolution of the given disease upon elimination of oral sepsis by extraction of the infected teeth. In this context, bacteria and or their toxic metabolites and reflex nervous irritation were considered to be the crucial factors. In successive years, the concept of “oral foci of infection” lost its attention. Nonetheless, there are many studies successively acknowledged periodontitis as a risk factor in the pathogenesis of assorted inflammatory eye diseases including scleritis, iritis, glaucoma, diabetic retinopathy (DR), uveitis, retinitis pigmentosa (RP), and Sjogren syndrome (SS).
  • 1.6K
  • 27 Jun 2022
Topic Review
T6SS-mediated Stress Responses Influence
The bacterial type VI secretion system (T6SS) is a protein secretion apparatus widely distributed in Gram-negative bacterial species. Many bacterial pathogens employ T6SS to compete with the host and to coordinate the invasion process. The T6SS apparatus consists of a membrane complex and an inner tail tube-like structure that is surrounded by a contractile sheath and capped with a spike complex. A series of antibacterial or antieukaryotic effectors is delivered by the puncturing device consisting of a Hcp tube decorated by the VgrG/PAAR complex into the target following the con-traction of the TssB/C sheath, which often leads to damage and death of the competitor and/or host cells. As a tool for protein secretion and interspecies interactions, T6SS can be triggered by many different mechanisms to respond to various physiological conditions.
  • 1.5K
  • 25 Jan 2021
Topic Review
Giardia lamblia
Giardia lamblia, also known as Giardia intestinalis, is a flagellated parasitic microorganism, that colonizes and reproduces in the small intestine, causing giardiasis. The parasite attaches to the epithelium by a ventral adhesive disc or sucker, and reproduces via binary fission. Giardiasis does not spread via the bloodstream, nor does it spread to other parts of the gastrointestinal tract, but remains confined to the lumen of the small intestine. Giardia trophozoites absorb their nutrients from the lumen of the small intestine, and are anaerobes. If the organism is split and stained, its characteristic pattern resembles the familiar "smiley face" symbol. Chief pathways of human infection include ingestion of untreated sewage, a phenomenon particularly common in many developing countries; contamination of natural waters also occurs in watersheds where intensive grazing occurs. Giardia infections occur worldwide, however Giardia lamblia is the most commonly identified intestinal parasite in the United States and Canada among children in day care centers, hikers, family members, homosexual male partners and immunocompromised adults. Approximately 20,000 cases per year in the United States are reported.
  • 1.5K
  • 25 Oct 2022
Topic Review
Acidobacteria
Acidobacteria is a phylum of bacteria. Its members are physiologically diverse and ubiquitous, especially in soils, but are under-represented in culture.
  • 1.5K
  • 29 Nov 2022
Topic Review
Microcystins
Harmful cyanobacterial blooms pose an environmental health hazard due to the release of water-soluble cyanotoxins. One of the most prevalent cyanotoxins in nature is microcystins (MCs), a class of cyclic heptapeptide hepatotoxins, and they are produced by several common cyanobacteria in aquatic environments. Once released from cyanobacterial cells, MCs are subjected to physical chemical and biological transformations in natural environments. MCs can also be taken up and accumulated in aquatic organisms and their grazers/predators and induce toxic effects in several organisms, including humans.
  • 1.5K
  • 14 Sep 2021
Topic Review
Medical Devices Associated Nosocomial Infections
Healthcare-associated infections (HAIs) are caused by nosocomial pathogens. HAIs have an immense impact not only on developing countries but also on highly developed parts of world. They are predominantly device-associated infections that are caused by the planktonic form of microorganisms as well as those organized in biofilms. This review elucidates the impact of HAIs, focusing on device-associated infections such as central line-associated bloodstream infection including catheter infection, catheter-associated urinary tract infection, ventilator-associated pneumonia, and surgical site infections associated with their peculiar microorganisms along with conventional and novel therapies.
  • 1.5K
  • 29 Mar 2022
Topic Review
ADP-Ribosyltransferase Toxin
ADP-ribosyltransferases (ARTs) are a well-known type of bacterial toxin. They transfer an ADP-ribose moiety from nicotinamide adenine dinucleotide (NAD+) onto a target protein to generate an ADP-ribosylated protein and nicotinamide. The bulky and negatively charged ADP-ribose moiety affects the protein function by sterically blocking interactions with partner molecules, inducing conformational changes, or creating docking sites for new interaction partners.
  • 1.5K
  • 25 Jan 2021
Topic Review
4-Hydroxybutyrate Containing Polyhydroxyalkanoates Production for Biomedical Applications
Polyhydroxyalkanoates (PHA) are polyesters having high promise in biomedical applications. Among different types of PHA, poly-4-hydroxybutyrate (P4HB) is the only polymer that has received FDA approval for medical applications. However, most PHA producing microorganisms lack the ability to synthesize P4HB or PHA comprising 4-hydroxybutyrate (4HB) monomer due to their absence of a 4HB monomer supplying pathway. Thus, most microorganisms require supplementation of 4HB precursors to synthesize 4HB polymers. 
  • 1.5K
  • 09 Dec 2021
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