To see the other types of publications on this topic, follow the link: Streptomyces; Antibiotics.
Dissertations / Theses on the topic 'Streptomyces; Antibiotics'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Streptomyces; Antibiotics.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Cooper, Howard N. "Tetronasin biosynthesis in Streptomyces longisporoflavus." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240902.
Full text
2
Smith, Todd M. "Genetic and biochemical studies of thiostrepton biosynthesis in Streptomyces laurentii /." Thesis, Connect to this title online; UW restricted, 1993. http://hdl.handle.net/1773/8187.
Full text
3
Aubry, Céline. "Towards combinatorial biosynthesis of pyrrolamide antibiotics in Streptomyces." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS245.
Full textAbstract:
Depuis plus de 80 ans, le métabolisme spécialisé nous fournit de nombreuses molécules utilisées en médecine, en particulier comme anti-infectieux. Aujourd’hui, avec l’augmentation mondiale de la résistance aux antimicrobiens, de nouveaux antibiotiques sont indispensables. Une des réponses à cette pénurie grave pourrait provenir de la biologie synthétique. Dans le domaine du métabolisme spécialisé, la biologie synthétique est utilisée en particulier pour la biosynthèse de métabolites non naturels. Parmi les métabolites spécialisés, les peptides non ribosomiques constituent une cible attrayante, car ils nous ont déjà fourni des molécules à haute valeur clinique (ex. les antibiotiques vancomycine et daptomycine). De plus, la plupart sont synthétisés par des enzymes multimodulaires appelées synthétases de peptides non ribosomiques (NRPS), et sont diversifiés davantage par des enzymes de décoration. Ainsi, ces voies de biosynthèse se prêtent particulièrement à la biosynthèse combinatoire, consistant à combiner des gènes de biosynthèse provenant de divers groupes de gènes ou, dans le cas des NRPS, à combiner des modules ou domaines pour créer de nouvelles enzymes. Cependant, si plusieurs études ont établi la faisabilité de telles approches, de nombreux obstacles subsistent avant que les approches combinatoires de biosynthèse soient totalement efficaces pour la synthèse de nouveaux métabolites. Les travaux présentés ici s’inscrivent dans le cadre d’un projet visant à comprendre les facteurs limitant les approches de biosynthèse combinatoire basées sur les NRPS, en utilisant une approche de biologie synthétique. Nous avons choisi de travailler avec les NRPS responsables de la biosynthèse des pyrrolamides. En effet, ces NRPS sont constitués uniquement de modules et de domaines autonomes, et donc particulièrement adaptés aux manipulations génétiques et biochimiques. La caractérisation du groupe de gènes de biosynthèse du pyrrolamide anthelvencine constitue la première partie de cette thèse et nous a fourni de nouveaux gènes pour notre étude. La deuxième partie a consisté à construire de vecteurs intégratifs modulaires, outils essentiels pour la construction et l’assemblage de cassettes génétiques. La dernière partie présente la reconstruction du groupe de gènes du pyrrolamide congocidine, basée sur la construction et l’assemblage de cassettes de gènes synthétiques. Dans l’ensemble, ces travaux ouvrent la voie à de futures expériences de biosynthèse combinatoire, expériences qui devraient contribuer à une meilleure compréhension du fonctionnement précis des NRPSFor more than 80 years, specialized metabolism has provided us with many molecules used in medicine, especially as anti-infectives. Yet today, with the rise of antimicrobial resistance worldwide, new antibiotics are crucially needed. One of the answers to this serious shortage could arise from synthetic biology. In the field of specialized metabolism, synthetic biology is used in particular to biosynthesize unnatural metabolites. Among specialized metabolites, non-ribosomal peptides constitute an attractive target as they have already provided us with clinically valuable molecules (e.g. the vancomycin and daptomycin antibiotics). In addition, most are synthesized by multimodular enzymes called non-ribosomal peptide synthetases (NRPS) and further diversified by tailoring enzymes. Thus, such biosynthetic pathways are particularly amenable to combinatorial biosynthesis, which consists in combining biosynthetic genes coming from various gene clusters or, in the case of NRPSs, combining modules or domains to create a new enzyme. Yet, if several studies have established the feasibility of such approaches, many obstacles remain before combinatorial biosynthesis approaches are fully effective for the synthesis of new metabolites. The work presented here is part of a project aiming at understanding the limiting factors impeding NRPS-based combinatorial biosynthesis approaches, using a synthetic biology approach. We chose to work with the NRPSs involved in the biosynthesis of pyrrolamides. Indeed, these NRPS are solely constituted of stand-alone modules and domains, and thus, particularly amenable to genetic and biochemical manipulations. The characterization of the biosynthetic gene cluster of the pyrrolamide anthelvencin constitutes the first part of this thesis, and provided us with new genes for our study. The second part involved the construction of modular integrative vectors, essential tools for the construction and assembly of gene cassettes. The final part presents the successful refactoring of the congocidine pyrrolamide gene cluster, based on the construction and assembly of synthetic gene cassettes. Altogether, this work paves the way for future combinatorial biosynthesis experiments that should help deciphering the detailed functioning of NRPSs
4
Eustáquio, Alessandra da Silva. "Biosynthesis of aminocoumarin antibiotics in streptomyces generation of structural analogues by genetic engineering and insights into the regulation of antibiotic production /." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11514125.
Full text
5
McDonald, Matthew G. "Biosynthetic studies on phenazine antibiotics /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8699.
Full text
6
Dong, Haijun. "Biosynthesis of validamycin A in Streptomyces hygroscopicus var. limoneus /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8612.
Full text
7
Sparkes, Andrew Windsor. "Studies of archaemycin biosynthesis." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239645.
Full text
8
Marsden, Andrew F. A. "The erthromycin-producing polyketide synthase." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243196.
Full text
9
Williams, Richard Stephen. "The molecular physiology of antibiotic production in Streptomyces coelicolor." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/696/.
Full text
10
Kieser, Helen M. "Analysis of the genome of Streptomyces coelicolor A3(2)." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302209.
Full text
11
Hu, Yiding. "The biosynthesis of manumycin type metabolites /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8479.
Full text
12
Allen, Ian. "The cloning and analysis of the genes specifying geldanamycin biosynthesis from Streptomyces hygroscopicus." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333630.
Full text
13
Obanye, A. I. C. "Carbon flux and the production of methylenomycin by Streptomyces coelocolor A3(2)." Thesis, University of Manchester, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506594.
Full text
14
Neu, John M. Wright Gerard D. "Protein kinases in Streptomyces : involvement in growth, glycopeptide production and resistance /." *McMaster only, 2002.
Find full text
15
Angell, Susan. "The glucose kinase gene of Streptomyces coelicolor A3(2) and its role in glucose repression." Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316060.
Full text
16
Gilbey, T. D. "Effects of metal ions on the physiology of growth and secondary metabolism of Streptomyces thermoviolaceus." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333684.
Full text
17
Leszcynski, Robert A. "Determination of the Relationship Between Bacterial Coculturing, Antibiotic Resistance and Bacterial Growth." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1591787505690696.
Full text
18
Ogunmwonyi, Isoken Nekpen Henrietta. "Assessment of antibiotic production by some marine Streptomyces isolated from the Nahoon Beach." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/264.
Full textAbstract:
Rapidly emerging strains of bacteria resistant to most advanced antibiotics have become issues of very important public health concern. Research currently directed towards marine actinomycetes presents a vast potential for new compounds that could be able to safely and effectively target resistant species. In this regard, ten putative Streptomyces strains isolated from the Nahoon beach were selected and assessed for antibiotic production and activity against a wide range of bacteria including reference strains, environmental strain and clinical isolates. The ethyl acetate extracts of the putative Streptomyces isolates showed activities against at least 6 and up to 26 of the 32 test bacteria. Inhibition zones were found to range between 9-32 mm diameters at a concentration of 10 mg/ml. The minimum inhibitory concentrations (MICs) of the crude extracts ranged from 0.039 - 10 mg/ml and the least minimum bactericidal concentration (MBC) demonstrated was 0.625 mg/ml against a reference strain Staphylococcus aureus ATCC 6538. Time kill kinetics of all extracts revealed bacteristatic and bactericidal activities. Average Log reductions in viable cell counts for all the extracts ranged from 0.86 Log10 and 3.99 Log10 cfu/ml after 3 h interaction and 0.01 Log10 and 4.86 Log10 after 6 h interaction at MIC, 2 × MIC, 3 × MIC and 4 × MIC concentrations. Most of the extracts were speedily bactericidal at 3 × MIC and 4 × MIC resulting in over 50 % elimination of most of the test bacteria within 3 h and 6 h interaction. The partial characterization of the crude extracts by IR spectral analysis revealed possibility of terpenoid, long chain fatty acids and secondary amine derivatives compounds in the extracts. It is therefore recommended that further investigation should address the relationship between the structure of the active component of the extracts and the broad spectrum activity, as well as a rapid method for large scale production and purification and whether this group of antibiotics has any application in managing human infectious disease.
19
Sembiring, Langkah. "Selective isolation and characterisation of streptomycetes associated with the rhizosphere of the tropical legume, Paraserianthes falcataria (L) Nielsen." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312046.
Full text
20
Idowu, Gideon Aina. "Investigations into the biosynthesis and mode of action of methylenomycin antibiotics from Streptomyces coelicolor." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/96060/.
Full textAbstract:
The genus Streptomyces is known to be responsible for the production of more than two-thirds of the world’s antibiotics, through complex specialised metabolic pathways. However, given the high frequency of rediscovery of known antibiotics and the challenge of producing novel analogues via chemical synthesis, biosynthetic engineering has emerged as an attractive approach to optimising antibiotic natural products for clinical use. This technique utilises enzymes from antibiotic biosynthetic pathways to create novel antibiotic derivatives. However, its application requires an understanding of how antibiotics are biosynthesised. This work is focused on the methylenomycin antibiotics produced by Streptomyces coelicolor A 3 (2), a model Actinobacterium. The cluster of genes directing methylenomycin production and its regulation are carried on the giant linear plasmid SCP1. The sequencing of the entire 356-kb SCP1 plasmid allowed bioinformatics analyses to be applied to the assignment of putative roles in methylenomycin biosynthesis for several of the enzymes encoded within the methylenomycin biosynthetic gene cluster. However, experimental evidence to support the proposed roles of several of these enzymes has yet to be obtained, while the roles of some of the proteins encoded by the cluster remain unclear. Here, work towards understanding the biosynthesis as well as the mode of action of the methylenomycin antibiotics is reported. In particular, the roles of MmyO and MmyF in the epoxidation of methylenomycin C to produce methylenomycin A are demonstrated via feeding of methylenomycin C to a methylenomycin-resistant derivative of S. coelicolor M145 expressing mmyO and mmyF. A putative butenolide intermediate in the pathway, believed to derive from a MmyD-catalysed condensation of acetoacetyl-MmyA with a pentulose, was identified in S. coelicolor strains expressing the methylenomycin biosynthetic gene cluster. The pattern of incorporation of [U-13C]-D-ribose into the putative butenolide intermediate was similar to that observed for methylenomycin C, indicating the former could indeed be a precursor to the latter. A putative intermediate of the pathway, pre-methylenomycin C, accumulating in a mmyE mutant strain, and its lactone form, pre-methylenomycin C lactone, were shown to be 16 and 256 times, respectively, more potent than methylenomycin A, against methicillin-resistant Staphylococcus aureus (MRSA). Expression of the methylenomycin resistance determinant (mmr) in Streptomyces species also confers no resistance against these two putative intermediates unlike methylenomycin A, the final antibiotic product of the pathway. Investigations into the mechanism of action of methylenomycin antibiotics with luciferase and β-galactosidase pathway-specific promoter-reporter fusion strains strongly suggest that the methylenomycins exert their antibiotic effects in bacteria primarily by targeting the biosynthesis of cell wall peptidoglycan, consistent with their activities mainly against Gram-positive strains. This is the first report of the mode of action of methylenomycin family of antibiotics.
21
Sultana, Azmiri. "Mechanistic insights into the biosynthesis of polyketide antibiotics /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7357-010-9/.
Full text
22
Akintunde, Olaitan G. "Production of an Antibiotic-like Activity by Streptomyces sp. COUK1 under Different Growth Conditions." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2412.
Full textAbstract:
Streptomyces are known to produce a large variety of antibiotics and other bioactive compounds with remarkable industrial importance. Streptomyces sp. COUK1 was found as a contaminant on a plate in which Rhodococcus erythropolis was used as a test strain in a disk diffusion assay and produced a zone of inhibition against the cultured R. erythropolis. The identity of the contaminant was confirmed as Streptomyces through 16S rRNA sequencing. This Streptomyces produces a strong inhibitory compound in different growth media. A culture extract from inorganic salts starch agar was found to be very active; producing a large zone of inhibition against several Gram positive and Gram negative test strains. The active molecules in this extract have been detected via TLC and bioautography. The difference in the antibacterial activity and chromatographic properties of extracts recovered from different growth media suggests that this Streptomyces strain could produce more than one type of inhibitory compound.
23
Carter, William E. "Response surface methodology for optimizing the fermentation of a cycloheximide producing streptomycete." Virtual Press, 2001. http://liblink.bsu.edu/uhtbin/catkey/1221297.
Full textAbstract:
Many antibiotics are produced as secondary metabolites of Streptomyces species. Commercial production of an antibiotic involves the optimization of environmental parameters, genetic makeup, and medium. Selection of ingredients for both inoculum (seed) and fermentation (production) media must provide for economic production, and easy downstream processing of the compound. Antibiotics are produced as secondary shunt metabolites and represent products that are not essential for primary metabolism of the cell; therefore conditions for their optimal expression may or may not be associated with good growth of the organism. Response Surface Methodology (RSM) is a collection of statistically designed experiments and analyses that directs the investigation of many factors and their interactions. This approach minimizes the number of trials required to identify critical factors and possible synergism between factors. In this research, an antifungal antibiotic produced by an unknown streptomycete collected from soil, was isolated, characterized and identified as cycloheximide. RSM was then used toformulate both a seed and production medium that optimizes cycloheximide biosynethesis. For the seed medium, RSM was used in a three step process: i) full factorial categorical screen of many factors, ii) Plackett-Burman two-level screen of promising factors, and iii) orthogonal central composite design of critical factors. Optimal 24 hour packed cell volume was found with a seed medium containing (g/L): 6.6g soluble starch, 23.4g yeast extract, and Mg K2HPO4. Additionally, the effects of inoculum age and passage on resulting cycloheximide production were studied. It was found that the negative effects of increasing inoculum age and passages on cycloheximide production could be mediated by the composition of the seed medium. For the production medium, RSM analysis of 29 ingredients suggests that an optimal production medium for cycloheximide biosynthesis should contain a combination of starch (40 g/L), corn gluten (17.8 g/L), MgSO4.7H2O (1.16 g/L), and NaCl (6.38 g/L). This final production medium resulted in a cycloheximide titer of 943 µg/ml, a 6-fold improvement in antibiotic production.Department of Biology
24
Pereira, Marie Antoinette Tanya. "Cellular differentiation and antibiotic production by Streptomyces nodosus immobilised in alginate capsules." View thesis, 2007. http://handle.uws.edu.au:8081/1959.7/20504.
Full textAbstract:
Thesis (PhD) -- University of Western Sydney, 2007.A thesis submitted to the University of Western Sydney, College of Health and Science, School of Natural Sciences, as a requirement for the degree of Doctor of Philosophy. Includes bibliography.
25
Shipley, Paul R. "The biosynthesis of the thiopeptide antibiotic thiostrepton /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/11559.
Full text
26
Tatjana, Veličković. "Optimizacija formulacije medijuma za proizvodnju antibiotika ciljanog delovanja primenom prirodnog izolata Streptomyces hygroscopicus." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=108239&source=NDLTD&language=en.
Full textAbstract:
Jedno od najvećih dostignuća u dvadesetom veku je bio pronalazak antibiotika i njihova primena u humanoj medicini. Međutim, vremenom se pokazalo da su izazivači bolesti mikroorganizmi koji “uče” i imaju sposobnost da se “menjaju”, što neminovno dovodi do pojave antibiotske rezistencije, a čemu ide u prilog široko rasprostranjena upotreba antibiotika u lečenju pacijenata i primena humanih antimikrobnih lekova u veterini i fitofarmaciji. Razvoj novih i unapređenje postojećih farmaceutika zahteva ogromna ulaganja koja se mogu ali i ne moraju vratiti godinama. Prvi korak u razvoju novog farmaceutika je identifikacija ciljanog antibiotskog delovanja metabolita izabranog proizvodnog mikroorganizma, nakon čega sledi optimizacija uslova biosinteze u smislu sastava medijuma za proizvodnju.Osnovni cilj ove doktorske disertacije je optimizacija formulacije medijuma za kultivaciju prirodnog izolata Streptomyces hygroscopicus u pogledu izvora makronutrijenata i njihovih količina, kako bi se metabolička aktivnost primenjenog proizvodnog mikroorganizma, u definisanim proizvodnim uslovima, usmerila ka sintezi antibiotika sa ciljanim delovanjem.Optimizacijom formulacije medijuma za kultivaciju prirodnog izolata Streptomyces hygroscopicus, u primenjenim eksperimentalnim uslovima, odabrani su najpogodniji izvori makronutrijenata i definisane su njihove optimalne koncentracije za proizvodnju antibiotika sa ciljanim delovanjem. Utvrđeno je da je biosinteza baktericida efikasnih protiv B. cereus ATCC 10876, S. aureus ATCC 11632 i P. aeruginosa ATCC 27853 najizraženija u medijumu sa fruktozom, sojinim brašnom i fosfatnim solima, dok je za dobijanje fungicida koji deluju na C. albicans ATCC 10231 i A. niger ATCC 16404 najadekvatnije primeniti medijum sa glukozom kao izvorom ugljenika i već pomenutim izvorima azota i fosfora pri čemu je odnos navedenih sastojaka medijuma specifičan za svaki test mikroorganizam. Sa tehnološkog aspekta, rezultati ovih istraživanja predstavljaju pouzdan izvor informacija za unapređenje proizvodnih karakteristika primenjenog biokatalizatora, izbor tehnike kultivacije, definisanje toka i optimizaciju postupka proizvodnje baktericida i fungicida sa krajnjim ciljem uvećanja razmera posmatranog bioprocesa.One of the greatest achievements in the twentieth century was the invention of antibiotics and their application in human medicine. However, over time, it has been proven that disease susceptors are "learning" microorganisms and have the ability to "change", which inevitably leads to the emergence of antibiotic resistance, which is in favor of widespread use of antibiotics in the treatment of patients and the application of human antibiotics in veterinary medicine and phytopharmacy. The development of new and the advancement of existing pharmaceuticals requires huge investments that may or may not be back for years. The first step in the development of a new pharmaceutical is the identification of the target antibiotic activity of the metabolite of the selected production microorganism, followed by the optimization of the conditions of biosynthesis in terms of composition of the production medium.The main goal of this PhD thesis is the optimization of the formulation of the medium for the cultivation of the natural isolate Streptomyces hygroscopicus in terms of the source of macronutrients and their amounts, in order to direct the metabolic activity of the applied production microorganism, in the defined production conditions, towards the synthesis of antibiotics with targeted action. By optimizing the formulation of the medium for the culture of the natural isolate Streptomyces hygroscopicus, in the applied experimental conditions, the most suitable sources of macronutrients were selected and their optimal concentrations for the production of antibiotics with targeted action were defined. The biosynthesis of bactericides was found to be effective against B. cereus ATCC 10876, S. aureus ATCC 11632 and P. aeruginosa ATCC 27853 most pronounced in the medium with fructose, soy flour and phosphate salts, while for the production of fungicides acting on C. albicans ATCC 10231 and A. niger ATCC 16404 most appropriately apply a glucose medium as carbon source and already mentioned sources of nitrogen and phosphorus wherein the ratio of said ingredients to the medium is specific to each test microorganism. From a technological point of view, the results of these studies represent a reliable source of information for improving the production characteristics of the applied biocatalyst, a selection of cultivation techniques, defining the flow and optimizing the production of bactericides and fungicides with the ultimate goal of increasing the size of the observed bioprocess.
27
Jansson, Anna. "Structural enzymology of the biosynthesis of polyketide antibiotics /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-916-1/.
Full text
28
Mackenzie, Alasdair. "Studies on the biosynthetic pathways of clavulanic acid and cephamycin C in Streptomyces clavuligerus /." Uppsala : Department of Molecular Biology, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200719.pdf.
Full text
29
Cox, James E. "Characterization of NonR, an esterase that confers nonactin resistance." Columbus, Ohio Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1073055586.
Full textAbstract:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xiii, 196 p.; also includes graphics (some col). Includes abstract and vita. Advisor: Robert W. Bruegemeier, Dept. of Pharmacy. Includes bibliographical references (p. 176-196).
30
Pickup, Karen Marie. "The influence of mycelial morphology on the ability of "Streptomyces" species to produce antibiotics in liquid culture." Thesis, University of Surrey, 1990. http://epubs.surrey.ac.uk/697/.
Full text
31
McErlean, Matthew Richard. "ACTINOMYCIN FAMILIAL DIVERSITY DRIVEN BY PHENOXAZINONE-CORE REACTIVITY." UKnowledge, 2019. https://uknowledge.uky.edu/pharmacy_etds/97.
Full textAbstract:
Actinomycins are a class of compounds consisting of phenoxazinone-like core attached to two peptidolactone rings, denoted as α and β. A unique component of a few families—actinomycins G, Y, and Z—is a chlorinated β-ring threonine residue. Families G and Y also contained an actinomycin that possess a β-ring heterocycle (actinomycins G5 and Y5, respectively); prior to this work, no β-ring heterocycle-containing actinomycins were reported for the Z family. Unlike other actinomycin derivatives, Y5’s cytotoxicity was abolished while still maintaining some antibacterial potency.
We constructed a model compound to probe the physical properties of the actinomycin core to test conditions under which heterocycle formation would occur. We also analyzed the gene clusters of these actinomycin producers for gene candidates to from this structural motif. We found the the actinomycin core aniline to have pKa values of 2.976 and 8.429 and a significant shift in UV absorption between 300-310nm when the group becomes charged. We also found cyclization conditions and no obvious gene candidates to form the β-ring heterocycle based on our gene cluster analysis. We hypothesize that the familial diversity of the actinomycin G, Y and Z familes is due to the reactivity of the phenoxazinone-like core.
32
Taylor, Helen. "The penicillin binding proteins and autolysins of Streptomyces coelicolor and their putative roles in resistance to β lactam antibiotics." Thesis, Liverpool John Moores University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288224.
Full text
33
Millán, Oropeza Aarón. "Comparative study of the proteome of S. coelicolor M145 and S. lividans TK24, two phylogenetically closely related strains with very different abilities to accumulate TAG and produce antibiotics." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS160/document.
Full textAbstract:
Les Streptomyces sont des bactéries filamenteuses du sol à Gram +. Elles sont connues pour leur capacité à produire des métabolites secondaires utiles en médecine et en agriculture. S. coelicolor et S. lividans sont des souches modèles phylogénétiquement proches. Elles ont cependant des capacités contrastées à accumuler des lipides de réserve de la famille des triacylglycérol (TAG) et produire des métabolites secondaires alors qu’elles possèdent des voies de biosynthèse similaires pour ces deux types de molécules. En présence de glucose, S. coelicolor produit des niveaux élevés de métabolites secondaires spécifiques et son contenu en TAG est faible alors que c'est le contraire chez S. lividans. En revanche, en présence de glycérol, les deux souches accumulent une quantité de TAG similaire mais S. coelicolor produit aussi des métabolites secondaires. Le but de la présente thèse était de déterminer les caractéristiques métaboliques différentielles qui sous-tendent les différentes capacités biosynthétiques de ces deux souches modèles. Pour ce faire, une analyse protéomique comparative sans marquage des souches cultivées en milieu R2YE liquide ou solide en présence de glucose ou de glycérol comme principales sources de carbone a été réalisée en utilisant la technique de chromatographie liquide couplée à de la Spectrométrie de Masse en tandem (LC-MS / MS). Au total, 2024 et 4372 protéines ont été identifiées à partir des cultures liquides et solides, représentant 24% et 50% du protéome théorique. Les études en liquide ont révélé que le métabolisme de S. lividans était principalement glycolytique alors que le métabolisme de S. coelicolor était principalement oxydatif. Elles ont également indiqué que ces caractéristiques pourraient être liées au catabolisme préférentiel des acides aminés par rapport au glucose chez S. coelicolor par rapport à S. lividans. De plus, cette thèse constitue la première analyse protéomique du métabolisme de ces deux souches modèles en présence de glycérolStreptomyces are filamentous Gram+ soil bacteria well known for their ability to produce secondary metabolites useful in medicine and agriculture. S. coelicolor and S. lividans are phylogenetically closely-related model strains but they have contrasted abilities to accumulate storage lipids of the TriAcylGlycerol (TAG) family and to produce secondary metabolites whereas they possess similar pathways for the biosynthesis of these molecules. In the presence of glucose, S. coelicolor produces high levels of specific secondary metabolites and its TAG content is low whereas it is the opposite for S. lividans. In contrast, in the presence of glycerol, the two strains accumulated similar amount of TAG but S. coelicolor still produces secondary metabolites. The aim of the present thesis was to determine the differential metabolic features supporting such different biosynthetic abilities. To do so, a comparative label-free shotgun proteomic analysis of the strains grown in liquid or solid R2YE media with glucose or glycerol as main carbon sources was carried out using Liquid chromatography−tandem mass spectrometry (LC−MS/MS). A total of 2024 and 4372 proteins were identified in liquid and solid cultures, representing 24% and 50% of the theoretical proteome, respectively. These studies revealed that S. lividans metabolism was mainly glycolytic whereas S. coelicolor metabolism was mainly oxidative. They also suggested that these features might be related to the preferential catabolism of amino acids over glucose of S. coelicolor compared to S. lividans. Furthermore, this thesis constituted the first proteomic analysis of the metabolism of these two model strains in the presence of glycerol
Streptomyces es un género de bacterias filamentosas Gram+ provenientes del suelo que son conocidas por su capacidad para producir metabolitos secundarios útiles en la medicina y agricultura. S. coelicolor y S. lividans son cepas modelo filogenéticamente próximas que presentan capacidades opuestas para acumular lípidos de reserva de la familia de los triglicéridos (TAG) y para producir metabolitos secundarios en tanto que ambas cepas poseen rutas metabólicas idénticas para la biosíntesis de éstas moléculas. En presencia de glucosa, S. coelicolor produce altos niveles de metabolitos secundarios específicos y su contenido de TAG es bajo mientras que en S. lividans el comportamiento es opuesto. Sin embargo, en presencia de glicerol, ambas cepas acumulan cantidades similares de TAG y S. coelicolor produce metabolitos secundarios. El objetivo de ésta tesis fue de determinar las características metabólicas que distinguen las diferentes capacidades biosintéticas mencionadas previamente. Por esto, un análisis protéomico comparativo sin marcaje de tipo “shotgun” fue realizado con las dos cepas cultivadas en medio R2YE líquido y sólido usando glucosa o glicerol como fuentes principales de carbono mediante Cromatografía Líquida en “tándem” acoplada a Espectrometría de Masas (LC-MS/MS). Un total de 2024 y 4372 proteínas fueron identificadas en cultivos en medio líquido y sólido, representando 24% y 50% del proteoma teórico, respectivamente. El presente estudio demostró que el metabolismo de S. lividans fue principalmente glicolítico mientras que el metabolismo de S. coelicolor fue principalmente oxidativo. También se sugiere que éstas características pueden estar relacionadas con la preferencia catabólica de aminoácidos sobre el catabolismo de glucosa de S. coelicolor comparada con S. lividans. Además, la presente tesis constituye el primer análisis proteómico del metabolismo de éstas dos cepas modelo en presencia de glicerol
34
Coze, Fabien. "Régulation du métabolisme primaire et biosynthèse d’antibiotiques par la souche d’intérêt industriel Streptomyces." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112323.
Full textAbstract:
Ce travail décrit l’analyse de la distribution des flux de carbones au sein de deux souches de Streptomyces coelicolor A3(2) : la souche sauvage nommée M145 et son mutant M1146 incapable de produire les antibiotiques actinorhodine, undecylprodigiosine, et l’antibiotique dépendant du calcium. Metabolite Balance Analysis et Isotopomer Balance Analysis sont mis en œuvre pour proposer un modèle de distribution des flux de carbones de S. coelicolor en phase exponentielle de croissance. Les souches M145 et M1146 sont cultivées dans un milieu minimum limitant en azote et leurs comportements métaboliques sont comparés. Dans la souche non productrice M1146, un taux de croissance plus élévé, un flux plus important dans la voie des pentoses phosphates, un flux plus faible au niveau du cycle de Krebs ainsi qu’une activité respiratoire plus faible sont mis en évidence. Cela traduit le coût énergétique important associé à la production d’actinorhodine par M145. De plus, ce travail propose un rôle important de la nicotinamide nucléotide transhydrogénase pour le maintien de l’homéostasie du NADPH lors de la production d’actinorhodine par M145. Comme il existe de bonnes corrélations entre les données expérimentales et celles issues de la modélisation au niveau des bilans carbones, des bilans de pouvoir réducteur et des échanges gazeux, il sera intéressant d’utiliser cette modélisation avec la technique de Flux Balance Analysis pour prédire les variations de la distribution des flux de carbones dans des mutants de S. coelicolor pour lesquels des gènes auraient été sur-exprimés ou délétésThis work describes an analysis of carbon flux distribution in two strains of Streptomyces coelicolor A3(2), namely the wild type strain M145 and its derivative M1146 that is no longer able to produce the antibiotics actinorhodin, undecylprodigiosin and the calcium dependent antibiotic. Metabolite Balance Analysis and Isotopomer Balance Analysis were used to propose a model for carbon flux distribution in S. coelicolor during the exponential phase of growth. Strains M145 and M1146 were grown under nitrogen limitation in minimal medium and their metabolic behaviour were compared. In the non-producing strain M1146, a higher growth rate, a higher flux via the pentose phosphate pathway, a decreased flux through the TCA cycle and a decreased respiratory activity were evidenced. This highlighted the high energetic cost for actinorhodin production in M145. In this paper, we also propose a key role for the nicotinamide nucleotide transhydrogenase in NADPH homeostasis in M145 during actinorhodin production. As there are good correlations between experimental data and the model in terms of carbon balance, reducing power balance and gas exchanges, this model will be of great interest for Flux Balance Analysis to predict carbon-flux distribution changes in S. coelicolor strains in which gene are deleted or overexpressed
35
Saenz, Charlotte Cesty Borda de. "Estudos de genes envolvidos na via biossintética do antibiótico antitumoral Cosmomicina." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-17042008-092436/.
Full textAbstract:
Cosmomicina é um antibiótico antitumoral produzido pela bactéria Streptomyces olindensis DAUFPE 5622. Estudos de expressão gênica demonstraram que genes cuja expressão esta relacionada a condições de estresse (dnaJ e 18hsp), assim como genes associados a via biossintética de cosmomicina, são expressos sob condições de produção do antibiótico. Genes que ainda tinham a função desconhecida foram selecionados (cosS e cosY) e foram realizados análises bioinformáticas destes atribuindo-lhes a função de regulador transcricional e ornitina ciclodesaminase, respectivamente. Um cassete para inativação desses genes foi construído visando a futura obtenção de mutantes nulos. Genes de glicosiltransferase (cosK e cosG) também apresentaram diferenças na expressão na presença do antibiótico. Neste trabalho, foi revelada a presença de uma hipotética glicosiltransferase que tem homologia com a B-daunosamine daunomy, glicosiltransferase envolvida na transferência de açúcares na biossíntese do antibiótico daunomicina.Cosmomycin is an antitumoral antibiotic produced by the soil bacteria Streptomyces olindensis DAUFPE 5622. Gene expression studies established that stress condition genes like dnaJ and 18hsp, and cosmomycin biosynthetic pathways genes are expressed under antibiotic production. Also the genes cosS and cosY (unknowns function), were selected and analyzed by bioinformatics techniques attributing a transcriptional regulator and ornithine cyclodeaminase functions, respectively. A cassette was constructed in order to inactivate these two selected genes and generating void mutants. Another gene cosK, with glycosiltransferase function, also presented differences in its expression when the antibiotic is produced. We described in this work the presence of a hypothetical glycosiltransferase related with B-daunosamine daunomy, which transfers sugar molecules in the biosynthesis of daunomycin antibiotic.
36
Hernandez, Camilo Adolfo Contreras. "Caracterização de genes biossintéticos do antitumoral cosmomicina D." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-19032014-092606/.
Full textAbstract:
A cosmomicina D é um policetídeo aromático da família das antraciclinas com propriedades antitumorais e antimicrobianas produzida por Streptomyces olindensis. A elucidação de genes responsáveis pela síntese desta molécula foi abordada neste trabalho com as técnicas de LDGW-PCR e PCR que permitiram amplificar fragmentos gênicos envolvidos na formação da aglicona. O cluster gênico completo foi caracterizado numa região de 43,1 kb produto do seqüenciamento do genoma, onde se agruparam funcionalmente 40 ORFs em varias categorias: síntese de aglicona, reguladores, glicosiltransferases, deoxiaçúcares, resistência e com função desconhecida. Visando obter mutantes nulos para os genes cosS e cosY foram construidos os plasmídeos pCCSII e pCCYII onde a transformação da cepa selvagem com pCCSII resulto na cepa mutante SoDS, deficiente em produção de cosmomicina. As analises dos produtos obtidos da expressão de ambos os genes mostrou um efeito na redução de cosmomicina e supressão de intermediários do complexo antitumoral.Cosmomycin D produced by Streptomyces olindensis is an aromatic polyketide of the anthracycline family with antitumor and antimicrobial properties. The amplification of genes responsible for the molecule synthesis were approached in this study by LDGW-PCR and PCR techniques, the obtained fragments showed high similarities with genes involved in aglycon core assembly. The complete gene cluster was characterized in a genome region of 43.1 kb product of genome sequencing, containing 40 ORFs grouped functionally into different categories: aglycon synthesis, regulators, glycosyltransferases, deoxisugars, resistance and unknown function. In order to obtain null mutants for cosS and cosY genes, the plasmids pCCSII pCCYII were constructed, the transformation of the wild strain with pCCSII result in SoDS mutant, deficient in production of cosmomycin. The analyses of the obtained products from the expression of both genes showed an effect in reducing cosmomycin levels and suppression of various intermediates in the antitumor complex.
37
Latorre, Leandro Ribeiro. "Purificação e caracterização de antraciclinas antibióticas de uma linhagem mutante de Streptomyces olindensis DAUFPE 5622." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46135/tde-31012019-095214/.
Full textAbstract:
A espécie Streptomyces olindensis DAUFPE 5622 produz o complexo antibiótico retamicina, que apresenta atividade contra leucemia em seres humanos mas possui limitações de uso devido ao seu grande efeito cardiotóxico. Uma linhagem mutante de S. olindensis, So20, obtida por tratamento da linhagem selvagem com MMS (metanossulfonato de metila), apresentou diferença qualitativa quanto à produção deste complexo antibiótico. O extrato metanólico das células desta linhagem mutante sofreu diversos tratamentos com solventes orgânicos e foi submetido a diversas técnicas de separação cromatográfica. Algumas substâncias foram parcialmente isoladas e foram submetidas a análise espectrométrica, que indicaram diferenças nas suas estruturas com relação ao complexo obtido da linhagem selvagem DAUFPE 5622. Algumas destas frações parcialmente purificadas da linhagem mutante foram testadas quanto a sua atividade antimicrobiana, contra Bacillus subtilis 007, e quanto sua capacidade de intercalação em fragmentos de DNA em gel de eletroforese, no ICB-USP, indicando resultados promissores.Streptomyces olindensis DAUFPE 5622 species produces the antibiotic complex retamycin, which are active against human leukemia, but is still not used in human treatments due to its cardiotoxic effects. The S. olindensis mutant, So20, obtained by treatment with MMS (methyl methanesulfonate), showed qualitative differences in the antibiotic production. The methanolic extract from these mutant strains cells was purified by means of solvent partition and by chromatographic purification techniques. Some compounds were partially purified and the analysis of their spectrometric data indicated structural differences from that obtained from DAUFPE 5622 strains. Some of these partially purified substances from mutant strains were tested for their antimicrobian activity, against Bacillus Subtilis 007, and for their DNA intercalation ability on eletroforesis gel, in the ICB-USP laboratories, showing promising results.
38
Wyszynski, Filip Jan. "Dissecting tunicamycin biosynthesis : a potent carbohydrate processing enzyme inhibitor." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:3a7a509d-dba0-4d5b-9a39-a883c872d758.
Full textAbstract:
Tunicamycin nucleoside antibiotics were the first known to target the formation of peptidoglycan precursor lipid I in bacterial cell wall biosynthesis. They have also been used extensively as inhibitors of protein N-glycosylation in eukaryotes, blocking the biogenesis of early intermediate dolichyl-pyrophosphoryl-N-acetylglucosamine. Despite their unusual structures and useful biological properties, little is known about their biosynthesis. Elucidating the metabolic pathway of tunicamycins and gaining an understanding of the enzymes involved in key bond forming processes would not only be of great academic value in itself, it would also unlock a comprehensive toolbox of biosynthetic machinery for the production of tunicamycin analogues which have the potential to act as novel therapeutic antibiotics or as specific inhibitors of medicinally important NDP-dependent glycosyltransferases. I – Cloning the tunicamycin biosynthetic gene cluster. We report identification of the tunicamycin biosynthetic genes in Streptomyces chartreusis following genome sequencing and a chemically-guided strategy for in silico genome mining that allowed rapid identification and unification of an operon fractured across contigs. Heterologous expression established a likely minimal gene set necessary for antibiotic production, from which a detailed metabolic pathway for tunicamycin biosynthesis is proposed. II – Natural product isolation and degradation. We have developed efficient methods for the isolation of tunicamycins from liquid culture in preparative quantities. A subsequent relay synthesis furnished advanced biosynthetic intermediates for use as precursors in the production of tunicamycin analogues and as substrates for the in vitro characterisation of individual Tun enzymes. III – Functional characterisation of tun gene products. Individual tun gene products were over-expressed and purified from recombinant E. coli hosts, allowing in vitro functional studies to take place. An NMR assay of biosynthetic enzyme TunF showed it acted as a UDP-GlcNAc-4-epimerase. Putative glycosyltransferase TunD showed hydrolytic activity towards substrate UDP-GlcNAc but failed to accept to the expected natural acceptor substrate, providing unexpected insights into the ordering of biosynthetic events in the tunicamycin pathway. Initial studies into the over-expression of the putative sugar N-deacetylase TunE were also described. IV – Towards synthesis of tunicamycin fragments. Investigations into a novel synthesis of D-galactosamine – a structural motif within tunicamycin – led to the unexpected observation of inverted regioselectivity upon RhII-catalysed C-H insertion of a D-mannose-derived sulfamate. This was the first example of N-insertion at the beta- rather than gamma-C-H based on conformation alone and warranted further investigation. The X-ray structure of a key sulfamate precursor offered valuable insights as to the source of this unique selectivity.
39
Marques, Daniela de Araujo Viana. "Produção e extração de ácido clavulânico de Streptomyces spp. por fermentação extrativa utilizando sistemas de duas fases aquosas." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/9/9135/tde-22032010-111244/.
Full textAbstract:
O ácido clavulânico (AC) é um potente inibidor de β-lactamases utilizado na área médica. Métodos alternativos, econômicos e simples para sua purificação são de grande interesse. Este trabalho objetivou produzir e extrair AC de Streptomyces spp. por fermentação extrativa utilizando sistema de duas fases aquosas (SDFA) - polietileno glicol (PEG)/sais fosfato. Foi selecionado o melhor produtor de AC entre sete linhagens de Streptomyces spp. Avaliou-se a influência de cinco fatores no cultivo do melhor produtor em frascos agitados (pH, temperatura, velocidade de agitação, concentrações das fontes de nitrogênio e de carbono), utilizando planejamento experimental estatístico. Definidas as melhores condições de cultivo, foram estudadas a produção e a extração do AC em fermentação extrativa utilizando SDFA em frascos agitados e em sistema descontínuo utilizando biorreator. Em biorreator também foram realizados o estudo termodinâmico do processo de fermentação nas condições ótimas obtidas nas etapas anteriores e a determinação do coeficiente volumétrico de transferência de massa (kLa), comparando os sistemas de fermentação no meio de cultivo simples (SF) e fermentação extrativa utilizando sistema SDFA PEG/sais fosfato (SFE) sem e com crescimento microbiano. A linhagem de Streptomyces selecionada como a melhor produtora de AC foi a DAUFPE 3060, a qual apresentou a maior produção desse inibidor, 494 mg/L em 48h, em frascos agitados nas condições: pH 6,0, 32°C, 150 rpm, 5 g/L de glicerol e 20 g/L de farinha de soja. Após a etapa de otimização realizada para o estudo da temperatura e da concentração de farinha de soja, variáveis mais significativas no estudo de seleção, a temperatura e a concentração de farinha de soja ótimas, foram 32°C e 40 g/L, respectivamente, com produção de 629 mg/L de AC em 48h. O estudo termodinâmico confirmou que a temperatura de 32°C é a máxima de produção do AC; após esse valor, inicia-se, gradualmente, a degradação do AC. No estudo da determinação do coeficiente de transferência de massa, kLa, sem crescimento microbiano, observaram-se valores maiores de kLa para o SF, devido à viscosidade do PEG utilizado no SFE. A massa molar do PEG e a velocidade de agitação foram as variáveis que mais influenciaram na extração de AC no SFE em frascos agitados, apresentando comportamento semelhante em biorreator. E, finalmente, o estudo da transferência de oxigênio do SFE utilizando SDFA com crescimento microbiano foi avaliado para otimizar a produção e a extração de AC. Os resultados obtidos demonstraram que existe uma faixa ideal de velocidade de agitação e de aeração para evitar o rompimento celular e aumentar a recuperação de AC.Clavulanic acid (CA) is a potent inhibitor of β-lactamases used in the medical field. Alternative methods, economic and simple purification are of great interest. This PhD project aims to produce and extract clavulanic acid of Streptomyces spp. By extractive fermentation using aqueous two-phase system (ATPS) - Polyethylene glycol (PEG)/phosphate salts. The best producer of clavulanic acid among seven strains of Streptomyces spp was selected. The influence of five factors in the cultivation of the best producer in flasks (pH, temperature, agitation velocity, concentrations of nitrogen and carbon sources) using statistical experimental design was evaluated. Defined the best cultivation conditions, the production and extraction of clavulanic acid by extractive fermentation using ATPS in flasks and in a batch system using a bioreactor was analyzed. In batch system using a bioreactor were also carried out the thermodynamic study of the fermentation process in optimum conditions determined in previous steps and also determined the volumetric mass transfer coefficient (kLa) comparing the fermentation systems in simple culture medium (SF) and in a extractive fermentation using aqueous two-phase system (ATPS) PEG/phosphate salts (SEF) medium with and without microbial growth. A strain of Streptomyces spp. selected as the best producer of AC was DAUFPE 3060, which showed the highest production of this inhibitor, 494 mg/L at 48h, in flasks under the conditions of pH 6.0, 32 °C, 150 rpm, 5 g/L of glycerol and 20 g/L of soybean flour. After the optimization step, the most significant variables in the study selection, temperature and concentration of soybean flour, were studied. The optimal values were 32 °C and 40 g/L of temperature and soybean flour concentration, respectively, with production of 629 mg/L of CA after 48h of cultivation. The thermodynamic study confirmed that 32 °C is the maximum temperature production of CA, after this value, starts gradually, the degradation of CA. In the study of volumetric mass transfer coefficient, kLa, without microbial growth, showed higher values of kLa for the SF, because the high viscosity of the PEG used in the SFE. The PEG molar mas and agitation velocity were the variables that most influenced the extraction of CA in flasks using a SFE, with similar behavior in a bioreactor. Finally, the study of oxygen transfer rate in SFE using ATPS with microbial growth was evaluated to optimize the production and extraction of CA. The results showed that there is an ideal range of agitation and aeration to prevent cell disruption and increase the CA recovery.
40
Wang, Hua. "Semi-synthesis and biological evaluations of tunicamycin lipid analogues and investigation of the tunicamycin biosynthetic pathway." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:05c43287-9f84-45f4-8db4-0fb6c2763816.
Full textAbstract:
Tunicamycins are potent antimicrobial agents but are also toxic to mammalian cells, which render them clinically impractical to use to treat infectious diseases. Instead, they have been used extensively as biochemical tools to study the N-linked glycosylation of proteins. However, despite such a routine application, their inhibitory mechanisms are still not clear. The central objective of this thesis was to develop novel tunicamycin analogues that are non-toxic to eukaryotic cells that could serve as potential antimicrobial drug candidates. We hypothesised that if we retain the lipid character of tunicamycin structure and modify the GlcNAc moiety then the antimicrobial activity would be retained but the tunicamycins inhibitory action towards GPT would be abolished, thus diminishing tunicamycins cytotoxicity towards mammalian cells. I - Semi-synthesis of the Tunicamycin Core Scaffolds and Lipid Analogues Semi-synthetic strategies were devised for isolating tunicamycin core scaffolds and for the selective addition of lipid chains at the 10'-N and 2"-N positions of tunicamycin, yielding the first library of novel tunicamycin lipid analogues. II - Biological Evaluations of the Tunicamycin Core Scaffolds and Lipid Analogues For the first time, the antibacterial activity of tunicamycins was shown to be dependent on the presence of a lipid chain. The tunicamycin core scaffolds were shown to lack antibacterial activity and cytotoxicity. More importantly, the library of tunicamycin lipid analogues with lipid chain length from seven to twelve carbons showed titrated antibacterial activity profile. Furthermore, the tunicamycin lipid analogues were not only found to have potent antibacterial and anti-M. tuberculosis activities but were non-cytotoxic compared to tunicamycins. The relative therapeutic index calculated for the tunicamycin lipid analogues was up to several thousand folds more than tunicamycins. III - Investigation of the tunB and tunF Knockout in the tun Gene Cluster The tunB and tunF single knockout mutations were made in the tun gene cluster by PCR-targeting and then heterologously expressed in S. coelicolor. The tunB knockout successfully abolished tunicamycin biosynthesis and showed evidence by MS the first existence of exo-glycal intermediates in sugar biology, further supporting the discovery of TunA as a novel NDP-sugar 5,6-dehydrogenase. IV - Investigation of the TunD and TunE Enzymatic Activities in Tunicamycin Biosynthetic Pathway The recapitulation of TunD glycosyltransferase and TunE deacetylase activities in vitro were attempted. Recombinant TunD was refolded from insoluble TunD inclusion bodies, while TunE was isolated in small quantities. However, no TunD and TunE activities were found using proposed intermediates. The co-translation of the tun gene cluster and the formation of multi-protein complex are proposed to be involved in the tunicamycin biosynthesis.
41
Calcutt, Michael John. "Pactamycin resistance in Streptomyces." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35191.
Full textAbstract:
The coupled transcription-translation system previously developed for Streptomyces lividans was modified such that it functioned using purified ribosomal subunits, a crude initiation factor preparation and a high speed supernatant fraction. This system was used to investigate antibiotic resistance mechanisms in two Streptomyces which synthesise inhibitors of translation. Resistance to either pactamycin in Streptomyces pactum or celesticetin in Streptomyces caelestis was due to ribosome modification. In each case, high level resistance was attributed solely to one ribosomal subunit, the 30S subunit of the S. pactum ribosome and the 50S subunit of the S. caelestis ribosome. Shotgun cloning experiments have enabled a pactamycin resistance determinant from S. pactum to be isolated in S. lividans. However, in the original pactamycin resistant clone the plasmid was unstable and in the absence of pactamycin selection pressure, only a deleted form could be recovered. When ribosomes from resistant subclones were analysed, it appeared that a ribosome modification system from S. pactum had been cloned. Ribosome reconstitution studies indicated that a property of 16S rRNA was responsible for resistance. Since the cloned resistance determinant was not homologous to 16S rRNA (as judged by Southern analysis), pactamycin resistance in S. pactum is probably due to post-transcriptional modification of 16S rRNA.
42
Zeng, Wei Rong. "Acute Effects of the Antibiotic Streptomycin on Neural Network Activity and Pharmacological Responses." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700026/.
Full textAbstract:
The purpose of this study is to find out that if antibiotic streptomycin decreases neuronal network activity or affects the pharmacological responses. The experiments in this study were conducted via MEA (multi-electrode array) technology which records neuronal activity from devices that have multiple small electrodes, serve as neural interfaces connecting neurons to electronic circuitry. The result of this study shows that streptomycin lowered the spike production of neuronal network, and also, sensitization was seen when neuronal network pre-exposed to streptomycin.
43
Peacock, Lynn Miranda. "Lipid metabolism is Streptomyces lividans TK24." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267659.
Full text
44
Symmons, Martyn Francis. "Crystallographic studies on polynucleotide phosphorylase from Streptomyces antibioticus." Thesis, Birkbeck (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412811.
Full text
45
Lewis, Huw David. "The regulation of polyketide antibiotic resistance in Streptomyces." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624950.
Full text
46
Jones, Tracey Ann. "Macrolide antibiotic resistance and production in Streptomyces narbonensis." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/29668.
Full textAbstract:
Narbomycin, a macrolide antibiotic produced by Streptomyces narbonensis, consists of a 14-atom polyketide to which the deoxyhexose sugar, desosamine, is attached. The aim of this study was to identify the desosamine biosynthetic gene cluster.;In Streptomyces there is a tendency for genes concerned with the same biochemical pathway to be grouped together in clusters. These biosynthetic gene clusters are often associated with genes conferring resistance to the antibiotic in the producing organism. The relationship between the resistance genes and the biosynthetic genes has been of great importance in studying antibiotic biosynthesis, since a number of biosynthetic clusters have been isolated using the corresponding resistance gene as a probe against cosmid libraries.;Two resistance determinants have been cloned from S. narbonensis, nmr A and nmrB. The nucleotide sequence was determined and both genes appear to encode 23S rRNA methyltransferases conferring MLS resistance.;A cosmid library of S. narbonensis DNA was constructed and probed with the narbomycin resistance genes. This led to the isolation of the narbomycin biosynthetic gene cluster. Mycaminose genes from the tylosin biosynthetic gene cluster of S. fradiae were also available as probes and were used in hybridisation analysis against the S. narbonensis cosmid library; leading to the identification of putative desosamine genes and a preliminary map of the narbomycin biosynthetic gene cluster.
47
Rayet, Arjinder Kaur. "Analysis of the aminoglycosides neomycin and streptomycin." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/26869.
Full textAbstract:
The aim of the study was the determination of neomycin and streptomycin aminoglycoside antibiotics in bovine kidney tissue at trace levels. The aminoglycosides contain no chromophore making detection difficult by conventional spectrophotometric detection and are highly polar making separation from tissue samples a multistep clean-up procedure.
48
Takano, Eriko. "ppGpp and antibiotic production in Streptomyces coelicolor A3(2)." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359366.
Full text
49
Zhou, Shanshan. "Antibiotic biosynthesis and its transcriptional regulation in Streptomyces bacteria." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/89468/.
Full textAbstract:
Streptomyces, the largest genus of Actinobacteria, are renowned for their ability to produce a wide variety of specialised metabolites, including many clinically used antibiotics and other bioactive natural products. Biosynthesis of these specialised metabolites is often tightly regulated by transcriptional regulators, some of which are responsive to signalling molecules, e.g., 2-alkyl-4-hydroxymethylfuran-3-carboxylic acids (AHFCAs), thus initiating a series of regulatory events. The biosynthetic role of MmfL in AHFCA assembly has been investigated in vitro using a synthetic substrate. MmfL has been shown to catalyse an AfsA-like reaction, involving condensation of an ACP-bound β-ketothioester and dihydroxyacetone phosphate to form a phosphorylated butenolide intermediate. The interactions between DNA, AHFCA ligands and ArpA-like repressors, MmfR and SgnR, have been investigated in vitro using electrophoretic mobility shift assays. This work leads to a better understanding of the regulation mechanism in specialised metabolite biosynthesis. Heterologous expression of a putative pyochelin-like gene cluster, sven0503-sven0517 from S. venezuelae ATCC 10712, has previously been shown to result in the production of thiazostatin and watasemycin as the main metabolic products of the cluster. Isopyochelin, a structural isomer of pyochelin, was also identified and characterised by comparison with synthetic standards. Sven0516 has previously been identified as the thiazoline reductase required for the biosynthesis of all of the metabolic products of the cluster. The class B radical SAM methylase Sven0515 was shown to be responsible for the methylation of thiazostatin to give watasemycin. This is the first experimentally validated example of such a reaction in the biosynthesis of a nonribosomal peptide. From incorporation experiments using stereospecifically deuterium-labelled cysteine, it has been demonstrated that Sven0515-mediated methylation proceeds with abstraction of the pro-R hydrogen atom and results in inversion of stereochemistry at the methylating position. The absolute stereochemistry of thiazostatin and watasemycin has been reassigned on the basis of the absolute configuration determined for isopyochelin.
50
Sahin, Nevzat. "Selective isolation, characterisation and classification of novel thermotolerant streptomycetes." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261094.
Full text