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Integrons in pseudomonads are associated with hotspots of genomic diversityWilson, Neil Lewis. January 2008 (has links)
Thesis (PhD)--Macquarie University, Division of Environmental & Life Sciences, Department of Biological Sciences, 2008. / Bibliography: p. 257-274.
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Phytotoxins produced by pathovars of Pseudomonas syringaeHorak, Julia M. January 2010 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
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Isolation, Characterization and Physiological Studies of Cyanide-Utilizing BacteriaSilva Avalos, Juan G. (Juan Guillermo) 12 1900 (has links)
Ten bacteria capable of growth on the metal-cyano complex, tetracyanonickelate (II) {K2 [Ni(CN)J } (TCN), supplied as the sole nitrogen source, were isolated. Seven isolates were identified as pseudomonads while the remaining three were classified as Klebsiella species. In addition to TCN, all isolates were able to utilize KCN although it was significantly more toxic. The degradation of TCN was most complete when supplied at growth-limiting concentrations, did not occur when ammonia was present, and resulted in the formation of nickel cyanide [Ni(CN)2] as a degradation product.
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Integrons in pseudomonads are associated with hotspots of genomic diversityWilson, Neil Lewis January 2008 (has links)
Thesis (PhD)--Macquarie University, Division of Environmental & Life Sciences, Department of Biological Sciences, 2008. / Bibliography: p. 257-274. / Literature review -- General materials and methods -- Characterisation of strain collection -- Distribution of integrons and gene cassettes in pseudomonas -- Genomic context of pseudomonas integrons -- Evolutionary analysis of pseudomonas spp. integrons 199 -- Final discussion -- Appendix -- References. / Integrons associated with mobile genetic elements have played a central role in the emergence and spread of multiple antibiotic resistance in many pathogenic bacteria. However, the discovery of integrons in the chromosomes of diverse, non-pathogenic bacteria suggests that integrons have a broader role in bacterial evolution. The Pseudomonas stutzeri species complex is a well studied model for bacterial diversity. Members of the complex are genetically closely related, but sub-taxa are not able to be defined by exclusively shared sets of phenotypic characters. Rather, on the basis of total DNA:DNA similarity, Ps. stutzeri strains have been divided into 17 different groups (termed genomovars). Two Ps. stutzeri strains have been found to contain Chromosomal Integrons (CIs). This thesis involved exploration of the hypothesis that a CI was present in the common ancestor of the Ps. stutzeri species complex and assessed the impact of integrons on diversity across all Pseudomonads. The history and significance of integrons is discussed in Chapter 1 as part of a literature review, and general materials and methods are provided in Chapter 2. Chapters 3 - 6 comprise the sections in which data generated during my PhD project are presented. A comprehensive analysis of the relationships between the strains being analysed is presented in Chapter 3. In Chapter 4, results of PCR and hybridisation screening for integrons across the strain collection are presented. In Chapter 5 the recovery of additional integrons and in depth sequence analysis of the recovered integrons are described. Finally, Chapter 6 contains statistical analyses of integron-associated genes and Chapter 7 contains a final discussion the most significant findings. Twenty-three Pseudomonas spp. strains were screened for the presence of integrons. All but three were found to contain integron-like sequences; however, most integron sequences recovered contained inactivated core integrons. viii Despite having a chromosomal locus, integrons in Pseudomonas were found to have properties indicative of frequent horizontal transfer. Evidence was also obtained which suggests that integrons have been acquired at the same locus on multiple independent occasions. This has not been observed in other families of chromosomal integrons and suggests that the loci at which integrons in Pseudomonas are found are hotspots for recombination. / Mode of access: World Wide Web. / xiii, 274 p. ill
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Pyrimidine Nucleoside Metabolism in Pseudomonads and Enteric BacteriaScott, Allelia Worrall 12 1900 (has links)
Metabolic differences in the strategies used for pyrimidine base and nucleoside salvage were studied in the pseudomonads and enteric bacteria. Fluoro--analogs were used to select mutant strains of E. coli, S. typhimurium, P. putida, and P. aeruginosa blocked in one or more of the uracil and uridine salvage enzymes. HPLC analysis of cell-free extracts from wild-type and mutant strains examined the effectiveness of the selections. Evidence was found for cytidine kinase in Pseudomonas and for an activity that converted uracil compounds to cytosine compounds. Using media supplemented with 150 μg of orotic acid per ml, P. putida SOC 1, a Pyr, upp mutant which utilizes orotic acid as a pyrimidine source was isolated for the first time in any study.
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Development of a numerical model to simulate the biological inactivation of airborne microorganisms in the presence of ultraviolet light.Noakes, C.J., Fletcher, L.A., Beggs, Clive B., Sleigh, P.A., Kerr, Kevin G. January 2004 (has links)
No / The effectiveness of any ultraviolet germicidal irradiation (UVGI) system is governed by the passage of airborne microorganisms through the UV field. This paper describes a new method for evaluating the performance of UVGI devices using computational fluid dynamic (CFD) simulations. A microorganism inactivation equation is combined with a scalar transport equation to describe the concentration of airborne microorganisms in the presence of a UV field. The solution of this equation, in conjunction with the momentum and turbulent energy equations, allows the effect of both the airflow and the UV field on the microorganism distribution to be examined. Solutions are shown for the airflow and microorganism concentration through a bench scale flow apparatus, at five different UV intensities. The results from the CFD model are validated against the experimental data, obtained from the flow apparatus, for aerosolised Pseudomonas aeruginosa microorganisms. Good comparisons are seen, giving confidence in the application of the technique to other situations.
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Repeatability of the Adaptation of Pseudomonas fluorescens to Low GlucoseTeselkin, Oleksiy 30 April 2014 (has links)
Inspired by Gould, who claimed life would be arriving at a different outcome each time it were allowed to run from the same beginning, I have attempted to determine the repeatability of the adaptive course of one Pseudomonas fluorescens lineage. In addition, my study aimed to establish whether the likelihood of parallel evolution of the two synonymous single-nucleotide substitutions was contingent upon a prior motility-impairing deletion or a prior increase in fitness. Further, the study was designed to provide empirical data addressing the long-standing question of the effect of starting fitness on the ensuing rate of adaptation.
Although no exact replay of the initial evolutionary trajectory was observed, I have demonstrated that gtsB, but not gtsC gene, is likely to be a mutational hotspot under the low glucose with a recovery of two undescribed mutations in gtsB. My data are consistent with a notion that substitutions in gtsB may be contingent upon Δ35kB(fliJ-PFLU4466) motility-impairing deletion, but not the fitness increase associated with it.
Finally, the features of the adaptive landscape of P. fluorescens in the minimal glucose provide languid support for Fisher’s hypothesis of a decrease in adaptation rate with the rise in the starting fitness.
Taken together, these original results reinforce the non-negligible role of history in shaping the outcomes of biological evolution and call for caution in attempting a formulation of rigid predictive models of evolutionary change.
Inspiré par les travaux de Stephen J. Gould qui affirmait que la vie sur terre arriverait à une forme différente si elle repartait à zéro, je présente ici mes travaux où je teste la reproductibilité du cours adaptatif d’une lignée expérimentale de Pseudomonas fluorescens. L’objectif de cette étude était de déterminer si la probabilité que deux mutations synonymes évoluent en parallèle est affectée par la présence d’une délétion affectant la motilité de la bactérie ou de l’augmentation de la valeur sélective de celle-ci. De plus, le design expérimental de cette étude permet de tester si la valeur sélective initiale d’une population affecte le taux d’adaptation de cette même population.
Bien d’une reproductibilité exacte du cours adaptatif initial ne fut pas observée, je démontre que le gène gtsB est probablement un « hotspot »mutationnel permettant l’adaptation à de bas niveau de glucose, ayant trouvé deux mutations dans ce site; alors que le gène gtsC ne l’est pas. Mes données sont également conséquentes avec le fait que les mutation dans le gène gtsB dépendent de l’effet de la délétion Δ35kB(fliJ-PFLU4466) affectant la motilité de la bactérie, mais non de l’augmentation de la valeur sélective qui y est associée. Finalement, la forme du plateau adaptative associé à de bas niveaux de glucose chez P. fluorescens supporte l’hypothèse émise par Fisher qui stipule que le taux d’adaptation d’un organisme diminue avec la valeur sélective initiale qui y est associée.
L’ensemble de ces résultats supporte le rôle non-négligeable de l’histoire de vie d’une population en ce qui attrait à l’évolution future de cette même population. Aussi, ces résultats appelle à la prudence quand vient le temps de formuler des modèles prédictifs des changements évolutifs d’une population.
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Repeatability of the Adaptation of Pseudomonas fluorescens to Low GlucoseTeselkin, Oleksiy January 2014 (has links)
Inspired by Gould, who claimed life would be arriving at a different outcome each time it were allowed to run from the same beginning, I have attempted to determine the repeatability of the adaptive course of one Pseudomonas fluorescens lineage. In addition, my study aimed to establish whether the likelihood of parallel evolution of the two synonymous single-nucleotide substitutions was contingent upon a prior motility-impairing deletion or a prior increase in fitness. Further, the study was designed to provide empirical data addressing the long-standing question of the effect of starting fitness on the ensuing rate of adaptation.
Although no exact replay of the initial evolutionary trajectory was observed, I have demonstrated that gtsB, but not gtsC gene, is likely to be a mutational hotspot under the low glucose with a recovery of two undescribed mutations in gtsB. My data are consistent with a notion that substitutions in gtsB may be contingent upon Δ35kB(fliJ-PFLU4466) motility-impairing deletion, but not the fitness increase associated with it.
Finally, the features of the adaptive landscape of P. fluorescens in the minimal glucose provide languid support for Fisher’s hypothesis of a decrease in adaptation rate with the rise in the starting fitness.
Taken together, these original results reinforce the non-negligible role of history in shaping the outcomes of biological evolution and call for caution in attempting a formulation of rigid predictive models of evolutionary change.
Inspiré par les travaux de Stephen J. Gould qui affirmait que la vie sur terre arriverait à une forme différente si elle repartait à zéro, je présente ici mes travaux où je teste la reproductibilité du cours adaptatif d’une lignée expérimentale de Pseudomonas fluorescens. L’objectif de cette étude était de déterminer si la probabilité que deux mutations synonymes évoluent en parallèle est affectée par la présence d’une délétion affectant la motilité de la bactérie ou de l’augmentation de la valeur sélective de celle-ci. De plus, le design expérimental de cette étude permet de tester si la valeur sélective initiale d’une population affecte le taux d’adaptation de cette même population.
Bien d’une reproductibilité exacte du cours adaptatif initial ne fut pas observée, je démontre que le gène gtsB est probablement un « hotspot »mutationnel permettant l’adaptation à de bas niveau de glucose, ayant trouvé deux mutations dans ce site; alors que le gène gtsC ne l’est pas. Mes données sont également conséquentes avec le fait que les mutation dans le gène gtsB dépendent de l’effet de la délétion Δ35kB(fliJ-PFLU4466) affectant la motilité de la bactérie, mais non de l’augmentation de la valeur sélective qui y est associée. Finalement, la forme du plateau adaptative associé à de bas niveaux de glucose chez P. fluorescens supporte l’hypothèse émise par Fisher qui stipule que le taux d’adaptation d’un organisme diminue avec la valeur sélective initiale qui y est associée.
L’ensemble de ces résultats supporte le rôle non-négligeable de l’histoire de vie d’une population en ce qui attrait à l’évolution future de cette même population. Aussi, ces résultats appelle à la prudence quand vient le temps de formuler des modèles prédictifs des changements évolutifs d’une population.
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Detection of aeromonas species in relation to the occurrence of estrogens and testosterone in various water resources in Limpopo Province, South Africa and Lusaka, ZambiaManavhela, Murendeni 18 May 2019 (has links)
MSc (Microbiology) / Department of Microbiology / Background: The occurrence of microorganisms and endocrine disrupting chemicals
(EDCs) in water poses a serious concern due to their effects on humans, animals and
environment. In recent years, EDCs have been increasingly reported in rivers that
receive large amounts of wastewater effluents. Of all the EDCs, natural and synthetic
hormones are among those that are recognized for their potential to mimic or interfere
with normal hormonal functions of humans and animals. The present study aimed at
assessing the occurrence of these hormones in relation to the molecular diversity of
Aeromonas and evaluating the resistance of Aeromonas to antibiotics as well as to
assess anti-bacterial activity of two selected traditional medicinal plants.
Methods: Wastewater, water and fish samples were collected from various sources
(rivers, wastewater treatment plants, taps, and dams) for the detection of hormones
and isolation of Aeromonas species. The analysis of hormones from various organs
of the fish and from water samples was conducted, after extraction using enzymelinked
immunosorbent assays (ELISA). Different types of hormones including Estriol,
Estradiol, Ethinylesradiol and Testosterone were detected, and their concentrations
determined. Aeromonas spp were isolated rom the samples using microbiological
methods and Conventional PCR was used for genotyping as well as for detection of
the beta-lactamase genes. Kirby-bauer method was used to determine the
susceptibility profiles of Aeromonas to different antibiotics. Microdilution assay was
used to determine the Anti-bacterial activity of the plant (Annoniceae and Zornia
milneana) extracts against Aeromonas species.
Results: A total of 144 samples were collected from 23 different locations in two
countries: South Africa and Zambia. These included wastewater and treated
wastewater, River water, fish and tap water. 17α-ethinylestradiol (EE2) was detected
in most of the samples (92.7%) with concentrations varying from 0.59 ng/ml to 65
ng/ml. The hormones were also detected from drinking water, with testosterone
detected at high concentrations of up to 140 ng/ml in tap water. Most sewage treatment
plants were not able to remove the EE2 from the wastewater as the concentration of
this hormone in the final effluent was almost always higher than that in the influent.
These homones were also detected in drinking water at high concentrations of up to
53.49 ng/ml in the tap water for EE2 and 1777 ng/ml for E2. The overall detection of
Aeromonas species in the samples was 84.5%. A. caviae was the most prevalent
species accounting for 73.6%, followed by A. veronii with 64.6%. The bacteria were
completely resistant to cefuroxime accounting for 100% resistance. Aeromonas
isolates also showed high resistance to trimethroprim (88.7% for A. hydrophila),
cefazolin (highest 97.8% for A. cavie), and ceftazidime (83.9% for A. sobria). TEM was
the most prevalent beta-lactamase gene with detection rate of 87%. All isolates lacked
the presence of the CTX-M3 gene. Also, wastewater had the highest prevalence of A.
veronni and A. caviae accounting for 87.5% and 82.5% respectively. Multiple antibiotic
resistance was also observed with the Aeromonas isolates being resistant to up to 11
antibiotics. High prevalence of 77.1% of Aeromonas hydrophila was observed in the
presence of ethinylestradiol (EE2). Aeromonas veronii and Aeromonas caviae were
the most predominant species in the presence of total estriol, A. veronii had a
prevalence of 57.1% and A. caviae had a prevalence of 52.8%. Aeromonas hydrophila
and Aeromonas caviae had the lower prevalence in the presence of hormones with
the percentages of 26.1% and 27.8% respectively. The methanol extracts of both
Zornia milneana and Annona species showed good activity against the Aeromonas
spp with the lowest MIC of 0.078 mg/ml. Ethyl acetate extracts were the least effective.
Conclusion: This study has shown high occurrence of steroid hormones in all types
of environmental samples tested. These included tap water, river water, wastewater
and fish both in Zambia and South Africa. Therefore, steroid hormones constitute and
important health problem in the Southern African Sub-Region. The incapacity of the
wastewater treatment plants to remove EE2 is an important problem that needs to be
tackled immediately. The prevalence of Aeromonas species is very high in our
environmental water as well as in drinking water, with the highest prevalence observed
in fish and wastewater. It was also revealed that there is relationship between steroid
hormones and Aeromonas species, with the hormones supporting the growth of
Aeromonas species. The presence of beta-lactamase genes which causes
Aeromonas to be resistant to antibiotics was also noted. Methanol extracts of Zornia
milneana and Annona spp were the most effective against Aeromonas spp and could
serve as primary sources for the isolation of lead compounds. / NRF
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