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Microorganisms May 2019Polyketides are a large group of secondary metabolites that have notable variety in their structure and function. Polyketides exhibit a wide range of bioactivities such... (Review)
Review
Polyketides are a large group of secondary metabolites that have notable variety in their structure and function. Polyketides exhibit a wide range of bioactivities such as antibacterial, antifungal, anticancer, antiviral, immune-suppressing, anti-cholesterol, and anti-inflammatory activity. Naturally, they are found in bacteria, fungi, plants, protists, insects, mollusks, and sponges. is a genus of Gram-positive bacteria that has a filamentous form like fungi. This genus is best known as one of the polyketides producers. Some examples of polyketides produced by are rapamycin, oleandomycin, actinorhodin, daunorubicin, and caprazamycin. Biosynthesis of polyketides involves a group of enzyme activities called polyketide synthases (PKSs). There are three types of PKSs (type I, type II, and type III) in responsible for producing polyketides. This paper focuses on the biosynthesis of polyketides in with three structurally-different types of PKSs.
PubMed: 31064143
DOI: 10.3390/microorganisms7050124 -
Frontiers in Microbiology 2022Antimicrobial resistance (AMR) is a serious threat to public health globally; it is estimated that AMR bacteria caused 1.27 million deaths in 2019, and this is set to...
Antimicrobial resistance (AMR) is a serious threat to public health globally; it is estimated that AMR bacteria caused 1.27 million deaths in 2019, and this is set to rise to 10 million deaths annually. Agricultural and soil environments act as antimicrobial resistance gene (ARG) reservoirs, operating as a link between different ecosystems and enabling the mixing and dissemination of resistance genes. Due to the close interactions between humans and agricultural environments, these AMR gene reservoirs are a major risk to both human and animal health. In this study, we aimed to identify the resistance gene reservoirs present in four microbiomes: poultry, ruminant, swine gastrointestinal (GI) tracts coupled with those from soil. This large study brings together every poultry, swine, ruminant, and soil shotgun metagenomic sequence available on the NCBI sequence read archive for the first time. We use the ResFinder database to identify acquired antimicrobial resistance genes in over 5,800 metagenomes. ARGs were diverse and widespread within the metagenomes, with 235, 101, 167, and 182 different resistance genes identified in the poultry, ruminant, swine, and soil microbiomes, respectively. The tetracycline resistance genes were the most widespread in the livestock GI microbiomes, including (W)_1, (Q)_1, (O)_1, and (44)_1. The (W)_1 resistance gene was found in 99% of livestock GI tract microbiomes, while (Q)_1 was identified in 93%, (O)_1 in 82%, and finally (44)_1 in 69%. Metatranscriptomic analysis confirmed these genes were "real" and expressed in one or more of the livestock GI tract microbiomes, with (40)_1 and (O)_1 expressed in all three livestock microbiomes. In soil, the most abundant ARG was the oleandomycin resistance gene, (B)_1. A total of 55 resistance genes were shared by the four microbiomes, with 11 ARGs actively expressed in two or more microbiomes. By using all available metagenomes we were able to mine a large number of samples and describe resistomes in 37 countries. This study provides a global insight into the diverse and abundant antimicrobial resistance gene reservoirs present in both livestock and soil microbiomes.
PubMed: 35875563
DOI: 10.3389/fmicb.2022.897905 -
Canadian Medical Association Journal Mar 1957
PubMed: 20325455
DOI: No ID Found -
Frontiers in Microbiology 2023The study aims to describe phageome of soil rhizosphere of in terms of the genes encoding CAZymes and other KEGG enzymes.
INTRODUCTION
The study aims to describe phageome of soil rhizosphere of in terms of the genes encoding CAZymes and other KEGG enzymes.
METHODS
Genes of the rhizospheric virome of the wild plant species were investigated for their ability to encode useful CAZymes and other KEGG (Kyoto Encyclopedia of Genes and Genomes) enzymes and to resist antibiotic resistance genes (ARGs) in the soil.
RESULTS
Abundance of these genes was higher in the rhizospheric microbiome than in the bulk soil. Detected viral families include the plant viral family Potyviridae as well as the tailed bacteriophages of class Caudoviricetes that are mainly associated with bacterial genera and . Viral CAZymes in this soil mainly belong to glycoside hydrolase (GH) families GH43 and GH23. Some of these CAZymes participate in a KEGG pathway with actions included debranching and degradation of hemicellulose. Other actions include biosynthesizing biopolymer of the bacterial cell wall and the layered cell wall structure of peptidoglycan. Other CAZymes promote plant physiological activities such as cell-cell recognition, embryogenesis and programmed cell death (PCD). Enzymes of other pathways help reduce the level of soil HO and participate in the biosynthesis of glycine, malate, isoprenoids, as well as isoprene that protects plant from heat stress. Other enzymes act in promoting both the permeability of bacterial peroxisome membrane and carbon fixation in plants. Some enzymes participate in a balanced supply of dNTPs, successful DNA replication and mismatch repair during bacterial cell division. They also catalyze the release of signal peptides from bacterial membrane prolipoproteins. Phages with the most highly abundant antibiotic resistance genes (ARGs) transduce species of bacterial genera , and . Abundant mechanisms of antibiotic resistance in the rhizosphere include "antibiotic efflux pump" for ARGs , and , "antibiotic target alteration" for , and "antibiotic inactivation" for .
DISCUSSION
These ARGs can act synergistically to inhibit several antibiotics including tetracycline, penam, cephalosporin, rifamycins, aminocoumarin, and oleandomycin. The study highlighted the issue of horizontal transfer of ARGs to clinical isolates and human gut microbiome.
PubMed: 37260683
DOI: 10.3389/fmicb.2023.1166148 -
Canadian Medical Association Journal Oct 1965The antibiotic treatment of staphylococcal infections remains a problem. Isolation of the organism and sensitivity testing are necessary in the choice of antibiotic.... (Review)
Review
The antibiotic treatment of staphylococcal infections remains a problem. Isolation of the organism and sensitivity testing are necessary in the choice of antibiotic. Penicillin G is the most effective penicillin against non-penicillinase-producing staphy-lococci; for the penicillinase producers there is very little to choose between the semisynthetic penicillins, methicillin, cloxacillin, nafcillin and oxacillin. For patients who are hypersensitive to penicillin, the bacteriostatic drugs (erythromycin, novobiocin, tetracycline, chloramphenicol, oleandomycin) are useful for mild infections, while for more severe illness the bactericidal drugs (vancomycin, ristocetin, kanamycin, bacitracin, neomycin) have been used successfully. Acute staphylococcal enterocolitis is probably best treated by a semisynthetic penicillin. Other antibiotics which have been found useful, with clinical trials, for staphylococcal infections are cephalosporin, fucidin, cephaloridine and lincomycin. The latter drug has been reported of value in the treatment of osteomyelitis. There is little justification for the prophylactic use of antibiotics to prevent staphylococcal infection. Surgical drainage is still an important adjunct in the treatment of many staphylococcal infections.
Topics: Anti-Bacterial Agents; Humans; Staphylococcal Infections
PubMed: 5318575
DOI: No ID Found -
Chest Mar 1995
Review
Topics: Adrenal Cortex Hormones; Asthma; Clinical Trials as Topic; Cyclosporine; Dapsone; Furosemide; Gold; Humans; Hydroxychloroquine; Magnesium Sulfate; Methotrexate; Treatment Outcome; Troleandomycin
PubMed: 7874959
DOI: 10.1378/chest.107.3.817 -
Molecular Microbiology Jun 1998A 5.2 kb region from the oleandomycin gene cluster in Streptomyces antibioticus located between the oleandomycin polyketide synthase gene and sugar biosynthetic genes...
A 5.2 kb region from the oleandomycin gene cluster in Streptomyces antibioticus located between the oleandomycin polyketide synthase gene and sugar biosynthetic genes was cloned. Sequence analysis revealed the presence of three open reading frames (designated oleI, oleN2 and oleR). The oleI gene product resembled glycosyltransferases involved in macrolide inactivation including the oleD product, a previously described glycosyltransferase from S. antibioticus. The oleN2 gene product showed similarities with different aminotransferases involved in the biosynthesis of 6-deoxyhexoses. The oleR gene product was similar to several glucosidases from different origins. The oleI, oleR and oleD genes were expressed in Streptomyces lividans. OleI and OleD intracellular proteins were partially purified by affinity chromatography in an UDP-glucuronic acid agarose column and OleR was detected as a major band from the culture supernatant. OleI and OleD showed oleandomycin glycosylating activity but they differ in the pattern of substrate specificity: OleI being much more specific for oleandomycin. OleR showed glycosidase activity converting glycosylated oleandomycin into active oleandomycin. A model is proposed integrating these and previously reported results for intracellular inactivation, secretion and extracellular reactivation of oleandomycin.
Topics: Amino Acid Sequence; Cloning, Molecular; Cosmids; Electrophoresis, Polyacrylamide Gel; Genes, Bacterial; Glycoside Hydrolases; Glycosylation; Glycosyltransferases; Molecular Sequence Data; Oleandomycin; Sequence Alignment; Sequence Analysis, DNA; Streptomyces; Streptomyces antibioticus; Substrate Specificity
PubMed: 9680207
DOI: 10.1046/j.1365-2958.1998.00880.x -
Journal of Bacteriology Jan 1992Cell extracts of Streptomyces antibioticus, an oleandomycin producer, can inactivate oleandomycin in the presence of UDP-glucose. The inactivation can be detected...
Cell extracts of Streptomyces antibioticus, an oleandomycin producer, can inactivate oleandomycin in the presence of UDP-glucose. The inactivation can be detected through the loss of biological activity or by alteration in the chromatographic mobility of the antibiotic. This enzyme activity also inactivates other macrolides (rosaramicin, methymycin, and lankamycin) which contain a free 2'-OH group in a monosaccharide linked to the lactone ring (with the exception of erythromycin), but not those which contain a disaccharide (tylosin, spiramycin, carbomycin, josamycin, niddamycin, and relomycin). Interestingly, the culture supernatant contains another enzyme activity capable of reactivating the glycosylated oleandomycin and regenerating the biological activity through the release of a glucose molecule. It is proposed that these two enzyme activities could be an integral part of the oleandomycin biosynthetic pathway.
Topics: Anti-Bacterial Agents; Drug Resistance, Microbial; Erythromycin; Glucosyltransferases; Glycosylation; Leucomycins; Macrolides; Oleandomycin; Streptomyces antibioticus
PubMed: 1530845
DOI: 10.1128/jb.174.1.161-165.1992 -
The FEBS Journal Jan 2022The translocon SecYEG and the associated ATPase SecA form the primary protein secretion system in the cytoplasmic membrane of bacteria. The secretion is essentially...
The translocon SecYEG and the associated ATPase SecA form the primary protein secretion system in the cytoplasmic membrane of bacteria. The secretion is essentially dependent on the surrounding lipids, but the mechanistic understanding of their role in SecA : SecYEG activity is sparse. Here, we reveal that the unsaturated fatty acids (UFAs) of the membrane phospholipids, including tetraoleoyl-cardiolipin, stimulate SecA : SecYEG-mediated protein translocation up to ten-fold. Biophysical analysis and molecular dynamics simulations show that UFAs increase the area per lipid and cause loose packing of lipid head groups, where the N-terminal amphipathic helix of SecA docks. While UFAs do not affect the translocon folding, they promote SecA binding to the membrane, and the effect is enhanced up to fivefold at elevated ionic strength. Tight SecA : lipid interactions convert into the augmented translocation. Our results identify the fatty acid structure as a notable factor in SecA : SecYEG activity, which may be crucial for protein secretion in bacteria, which actively change their membrane composition in response to their habitat.
Topics: Adenosine Triphosphatases; Cardiolipins; Escherichia coli; Escherichia coli Proteins; Fatty Acids, Unsaturated; Lipid Bilayers; Membrane Proteins; Oleandomycin; Phospholipids; Protein Transport; SEC Translocation Channels; SecA Proteins; Tetracycline
PubMed: 34312977
DOI: 10.1111/febs.16140 -
The Journal of Antibiotics Mar 1989The antimicrobial activity of a new semi-synthetic oral erythromycin derivative, ER 42859, was evaluated in vitro and in vivo in comparison with erythromycin,...
The antimicrobial activity of a new semi-synthetic oral erythromycin derivative, ER 42859, was evaluated in vitro and in vivo in comparison with erythromycin, spiramycin, josamycin, oleandomycin and the newer semi-synthetic derivatives flurithromycin, roxithromycin and A-56268. MIC values of ER 42859 were superior to those of roxithromycin, oleandomycin, josamycin and spiramycin but generally 2-fold poorer than those of erythromycin. The activity equalled that of erythromycin against Haemophilus influenzae and was superior to that of roxithromycin and A-56268 against this organism. MIC values of the compound were greatly influenced by pH due to the dibasic nature of the molecule. ER 42859 had markedly superior activity to erythromycin, spiramycin, josamycin, oleandomycin and flurithromycin against experimental infections in mice and similar activity to roxithromycin and A-56268. Blood and tissue levels were high and prolonged in rodents. In volunteers, blood levels were prolonged but inferior to those of erythromycin.
Topics: Animals; Erythromycin; Mice; Microbial Sensitivity Tests; Mycoplasma; Pneumococcal Infections; Tissue Distribution
PubMed: 2708138
DOI: 10.7164/antibiotics.42.454