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Microbial metabolism of C1 compoundsSmit, Franchoan 29 May 2014 (has links)
M.Sc. (Biochemistry) / Please refer to full text to view abstract
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Synthesis and Evaluation of Structural Analogues of Escherichia coli Lipid A for Application Towards CD14-Targeting GlycotherapeuticsBongat, Aileen Fay Galos. January 2008 (has links)
Title from title page of PDF (University of Missouri--St. Louis, viewed Feb. 10, 2010). Includes bibliographical references.
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Microbial and chemical dynamics during marula fermentationPhiri, Archie January 2018 (has links)
Thesis (MSc. (Microbiology)) --University of Limpopo, 2018 / Refer to the document / National Research Foundation (NRF)
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Synthesis of small molecules with specific function : I. Peptidocalix[4]arenes as molecular receptors ; II. Towards the total synthesis of (-)-Dihydroguaiaretic acidBrewster, Rachel Elizabeth 07 June 2004 (has links)
No description available.
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Synthesis of small molecules with specific function I. Peptidocalix[4]arenes as molecular receptors ; II. Towards the total synthesis of ( - )-Dihydroguaiaretic acid /Brewster, Rachel Elizabeth, January 2004 (has links) (PDF)
Thesis (Ph. D.)--School of Chemistry and Biochemistry, Georgia Institute of Technology, 2004. Directed by Suzanne B. Shuker. / Includes bibliographical references.
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Microbiotic assessment of an upflow anaerobic/aerobic swine treatment processMcClain, Robert Earl. January 2001 (has links)
Thesis (Ph. D.)--Mississippi State University. Department of Civil Engineering. / Title from title screen. Includes bibliographical references.
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The role of activated sludge extracellular polymers and aerobic biomass in the removal of phosphorus from wastewaterOosthuizen, Daniël Jacobus 15 February 2006 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted
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Testing Monod : growth rate as a function of glucose concentration in Saccharomyces cerevisiaeMrwebi, Mandisi 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The complexity of microbial systems has presented serious obstacles to the quantification of
fermentation processes. Using computer modelling techniques progress has been made in
monitoring, controlling and optimising microbial systems using material balancing techniques and
empirical process models. The Monod equation is among the most commonly used models and is
based on empirical findings with no mechanistic basis. Monod presents a simple model to describe
the growth of a cell in a defined nutrient environment. The Monod equation is mathematically
analogous to the formula that was proposed by Michaelis and Menten to describe enzyme kinetics.
Both equations describe a hyperbolic function with a half-saturation constant (K_s in the monod
equation and K_m in the Michaelis Menten equation) but the meaning of the two saturation constants
K_s and K_m is different. In number of studies K_s and K_m are used as if they are equivalent. In
contrast to Michaelis-Menten kinetics, which describes a process catalysed by a single enzyme,
Monod kinetics describes an overall process involving thousands of enzymes.
The Monod equation describes the specific growth rate of a microbial cell as the function of a
limiting substrate concentration. The aim of this study was to test this principle, for Saccharomyces
cerevisiae VIN13 under glucose limited aerobic chemostat conditions. The VIN13 was observed to
follow the Monod description and when compared with other growth kinetic models gave one of the
best fits to the data. A functional relationship between the half-saturation constant, K_s, and
Michaelis Menten constant, K_m, was there after derived. This was achieved by using metabolic
control analysis (MCA) to explain when K_m of the transporter becomes equal to the K_s. Using the
deductions obtained from MCA a core kinetic model was then formulated to demonstrate that the
K_s can either be smaller, equal or higher than the K_m of the transporter, depending on the flux
control distribution in the model. / AFRIKAANSE OPSOMMING: Die kwantifisering van fermentasieprosesse word ernstig belemmer deur die kompleksiteit van
mikrobiale sisteme. Deur gebruik te maak van rekenaar-ondersteunde modelleringstechnieke vir die
opstelling van massa balans vergelykings en empiriese prosesmodelle is vordering gemaak in die
waarneming, beheer en optimalisering van mikrobiale sisteme. Die Monod vergelyking is een van
die mees gebruikte groeimodelle en is gebaseer op empiriese bevindings - die model het nie ‘n
meganistiese grondslag nie. Die Monod vergelyking is wiskundig ekwivalent aan die vergelyking
wat opgestel is deur Michaelis en Menten vir die beskrywing van ensiemkinetika. Beide
vergelykings beskryf ‘n hyperboliese kurwe met ‘n konstante wat die halfversadigingswaarde
aangee vir substraat (Ks in die Monod vergelyking en Km in die Michaelis-Menten vergelyking),
maar die betekenis van die twee versadigingskonstantes is verskillend. In ‘n aantal studies word die
Ks en Km waardes gebruik asof hulle gelyk is aan mekaar. In teenstelling met die Michaelis-
Menten kinetika wat ‘n enkel ensiem-gekataliseerde reaksie beskryf, beskryf die Monod
vergelyking ‘n proses wat duisende ensieme behels.
Die Monod vergelyking beskryf die spesifieke groeitempo van ‘n bakteriële sel as ‘n funksie van
die beperkende substraatkonsentrasie. Die doel van hierdie studie was om hierdie beginsel te toets
vir Saccharomyces cerevisiae VIN13 wat onder glukose beperkte, aerobiese kondisies in ‘n
chemostat gekweek word. Die VIN13 groei kon goed beskryf word met die Monod model, wat in
vergelyking met ander groeimodelle een van die beste passings vir die meetpunte het gegee.
Vervolgens is ‘n funksionele verwantskap afgelei tussen Ks en Km; deur gebruik te maak van
metabole kontrole analise (MCA) kon verduidelik word wanneer die Ks gelyk is aan die Km van die
transporter vir die beperkende substraat. Deur gebruik te maak van die MCA analise is ‘n
eenvoudige kinetiese model opgestel om aan te toon dat die Ks kleiner, gelyk aan of groter kan wees
as die Km van die transporter, afhanklik van die fluksie-kontrole verdeling in die model.
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Seasonal variation of microflora and their effects on the quality of wood chips intended for pulping.Govender, Lucretia. 11 November 2013 (has links)
Eucalyptus, pine and wattle are the predominant exotic wood species used in the production of dissolving pulp in South Africa. On entering the mill, wood is chipped and stored in outdoor piles where it becomes vulnerable to microbial degradation and spontaneous combustion. Major losses of stored chips are due to high temperatures and combustion caused by heat energy released by microbial fermentation. Changes in the chemistry of the wood chips caused by the metabolic activity of indigenous microflora combined with the inherent chemical characteristics of each wood species could have a potential impact on final pulp quality and yield. Therefore the objective of this study was to analyse the microbial (bacteria and fungi) communities present in commercial wood chip piles and correlate this with changes in the chemistry of the wood in summer and winter.
The molecular fingerprinting technique of Denaturing Gradient Gel Electrophoresis (DGGE) was optimized for the detection of microbial diversity in commercial wood chips. Wood chips were collected from an industrial wood yard and milled to different specifications. A total of four primer sets with GC-clamps were tested in nested PCR for DGGE analysis. 16S and 18S rRNA genes were amplified using 338f-GC/518r; 933F-GC/1387R (bacteria) and NS26/518R-GC; EF4F/518R-GC (fungi), respectively. Several gel gradients were examined to determine optimal separation of bacterial (40/60%, 35/50%, 30/60%) and fungal (35/50%, 20/45%, 25/50%) PCR-DGGE products. Comparison of the DGGE profiles revealed greater diversity in the milled wood chips amplified using primer sets; 338F-GC/518R (16S) and NS26/518R-GC (18S) with gradients of 30/60% (16S) and 25/50% (18S). Once optimized, this standardized protocol was tested against five samples to assess its applicability to woodyard samples. 16S and 18S DGGE profiles were generated and amplicons excised from gels, re-amplified, sequenced and the microorganism from which the DNA originated was determined. In the second phase a cross-sectional study of wood chip piles from a commercial dissolving pulp mill was conducted with sample collected in summer and winter using the optimized PCR-DGGE technique. Microbial strains were identified after sequencing of 16S and 18S rRNA amplicons separated by DGGE. Chemical characteristics of the wood chips were evaluated by conducting extractive analyses using HPLC. Due to unpredictable combinations of different wood species in commercial wood chip piles, the third phase involved the investigation of individual Eucalyptus species. The microflora indigenous to the two Eucalyptus species (E. dunnii and E. nitens) and a combination of the
two were subjected to winter and summer simulations for one month during which samples were tested for wood chemistry properties, microflora and the final samples were used to generate dissolving pulp.
Using the PCR-DGGE method eighteen bacterial and twelve fungal species were identified from the five samples collected from the commercial wood chip pile, compared to the ten bacterial and nine fungal isolates which were identified using the culturing technique and standard 16S and 18S rRNA gene sequence analysis. Predominant genera in the optimization phase of this study were Klebsiella spp. (×3), Bacillus spp. (×2), Pantoea spp. (×2), Pseudomonas spp. (×2) and Paecilomyces spp. (×2). Application of the optimized DGGE technique to samples collected from the commercial pulping mill in summer and winter revealed variable profiles indicating a range of bacterial and fungal strains that varied in intensity in the areas and seasons sampled. Seventy nine (45 in summer and 34 in winter) and 29 (20 in summer and 9 in winter) distinct amplicons representing bacteria and fungi, respectively, were visualized. Predominant genera in summer were Pantoea rodasii, Inquilinus limosus, Streptococcus sp., Klebsiella spp., Diversispora sp., Boletaceae sp., Scutellospora sp., and Ophiostoma bicolour. In winter the prevailing genera were Leuconostoc palmae, Streptococcus sp., Bacillus spp., Diversispora sp., Boletaceae sp., and Bullera sp. Lower cellulose levels in summer correlated significantly with high microbial loads and the predominance of Bacillus spp., suggesting that in warm humid environments storage should not exceed 1-2 weeks. No correlations were determined between the decreased hot water levels in winter and microbial activity, however they were correlated to increased exposure of those samples to environmental factors. Chemistry data on the wood chips imparts the quality of the wood which only permitted projection of final pulp quality. This inadequacy was addressed in the third phase which included identification of microbial strains, originating from the individual Eucalyptus species, after sequencing of 16S and 18S rRNA amplicons separated by DGGE. Fungal and bacterial species were also isolated, cultured, identified and screened for lignocellulolytic enzyme activity. Ninety two and 88% of the fungi isolated were capable of producing cellulase and xylanase, respectively. Significant correlations exist between the microflora, seasons (greater diversity and loading in summer) and the chemical and physical properties of wood chips (lower cellulose and viscosity in summer) as well as Eucalyptus species (significantly higher cellulose and viscosity for the combination and E. nitens). Indigenous microflora of each wood species may be one of the contributing factors to poor/good pulp quality, as significant correlations
were made between enzyme production of microorganisms and wood chemistry which ultimately has an impact on the final pulp quality and yields. This investigation provides proof of concept that combining wood species with different deterioration rates results in an overall improvement in pulp quality and thus paves the way for a practical and applicable approach to managing quality of chips. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2013.
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Produção de exopolissacarídeos pelos fungos endofíticos Neofusicoccum parvum, Fusarium sp e Colletotrichum gloeosporioides : caracterização química e atividade anticoagulante /Grigoli Dominato, Angélica Augusta. January 2017 (has links)
Orientador: Maria de Lourdes Corradi da Silva / Coorientador: Ana Flora Dalberto Vasconcelos / Banca: Eliana Gertrudes Macedo Lemos / Banca: Roberto da Silva / Banca: Maria Antônia P. Colabone Celligoi / Banca: Luis Octavio Regasini / Resumo: A atividade metabólica fúngica, especialmente nos endofíticos, favorece a secreção de moléculas como antibióticos, pigmentos, enzimas e polissacarídeos, que podem ser aplicadas nas indústrias alimentícia, cosmética, farmacêutica, entre outras. A diversidade química dos exopolissacarídeos (EPS) bem como a possibilidade de sua utilização como substrato para diferentes modificações químicas (carboxilação, sulfatação e metilação) aumentam seu espectro de aplicação. Realizar o cultivo submerso dos fungos endofíticos Neofusicoccum parvum, Fusarium sp e Colletotrichum gloeosporioides para a produção de EPS foi o primeiro objetivo deste trabalho. Uma vez obtidos, os EPS foram purificados e quimicamente caracterizados. Sulfatação e ensaio da atividade anticoagulante foram realizados. Os parâmetros concentração de inóculo e tempo de cultivo foram estabelecidos para maior produção dos EPS, por fermentação submersa. Etapas de purificação, por centrifugação, foram efetuadas após análises por cromatografia de exclusão estérica a alta pressão, com detecção por índice de refração (HPSEC/RID). Os EPS purificados [precipitado do C. gloeosporioides (C. gloeosporioidesprec) e os três sobrenadantes] mostraram-se praticamente isentos de proteínas. A hidrólise ácida e subsequente análise dos hidrolisados por cromatografia de troca aniônica a alta pressão com detecção por amperometria pulsada (HPAEC/PAD) indicaram que apenas o C. gloeosporioidesprec era uma glucana. A análise por cromatografia... / Abstract: Fungal metabolic activity, especially in the endophytic, favors secretion of molecules such as antibiotics, pigments, enzymes and polysaccharides, which can be applicable by food, cosmetic and pharmaceutical industries, and others. The chemical diversity of the exopolysaccharides (EPS), as well as the possibility of their use as substrate for different chemical modifications (carboxylation, sulfation and methylation) increases their application spectrum. Submerged cultivation of the endophytic fungi Neofusicoccum parvum, Fusarium sp and Colletotrichum gloeosporioides for the production of EPS was the first aim of this study. Once the EPS were obtained, they were purified and chemically characterized. Chemical modification by sulfation and anticoagulant activity assays were performed. Cultivation to obtain EPS were performed in submerged fermentation. The inoculum concentration and incubation time parameters were set in order to obtain a higher amount of EPS. Purification by centrifugation was performed after analysis by high pressure steric exclusion chromatography with refractive index detection (HPSEC / RID). Purified EPS [precipitate of C. gloeosporioides (C. gloeosporioidesprec) and the three supernatants] proved to be virtually free of protein polysaccharides. Acid hydrolysis and subsequent analysis of the hydrolysates with high performance anionic exchange chromatography with amperometric detection (HPAEC/PAD) indicated that only the C. gloeosporioidesprec was a glucan. Analysis from gas chromatography and mass spectrometry showed a single derivative, 1,3,5-tri-Oacetyl, 2,4,6-tri-O-methyl glucitol with mass fragments (m/z 118, 161, 203, 234.1) consistent with a (1→3)-glucan. FT-IR spectra showed absorption bands typical from carbohydrate and signals in the digital region at 926 cm-1 and 820 cm-1, typical of polysaccharides in the α- configuration. These results were... / Doutor
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