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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Towards the discrimination of milk (origin) applied in cheddar cheese manufacturing through the application of an artificial neural network approach on Lactococcus lactis profiles

Venter, P., Venter, T., Luwes, N., De Smidt, O., Lues, J.F.R. January 2013 (has links)
Published Article / An artificial neural network (ANN) that is able to distinguish between Cheddar cheese produced with milk from mixed and single breed sources was designed. Samples of each batch (4 pure Ayrshire/4 mixed with no Ayrshire milk) were ripened for 92 days and analysed every 14 days. A novel ANN was designed and applied which, based only on Lactococcus lactis counts, provided an acceptable classification of the cheeses. The ANN consisted of a multi-layered network with supervised training arranged in an ordered hierarchy of layers, in which connections were allowed only between nodes in immediately adjacent layers.
12

Nested PCR for distinguishing Haemophilus haemolyticus from Haemophilus influenzae and Cloning and expression of fragmented Moraxella catarrhalis IgD-binding protein in E. coli

Bergström, Jennie January 2007 (has links)
<p>ABSTRACT</p><p>Nontypable Haemophilus influenzae is a common cause of otitis, sinusitis and conjunctivitis. It is the most common bacterial pathogen associated with chronic obstructive pulmonary disease (COPD). Studies have shown that nonpathogenic Haemophilus haemolyticus are often mistaken for Haemophilus influenzae due to an absent hemolytic reaction on blood agar. Distinguishing H. haemolyticus from H. influenzae is important to prevent unnecessary antibiotic use, and to understand the role of H. influenzae in clinical infections. In this study, PCR-primers for amplifying 16S rDNA sequences were used to set up a method for distinguishing H. haemolyticus from H. influenzae. The aim was to use the method for analyzing apparent H. influenzae strains, to investigate if some strains were in fact H. haemolyticus. However, because of problems with unspecific primerannealing,no conclusions could be drawn regarding misclassification of H. haemolyticus.</p><p>Moraxella catarrhalis is the second most common bacterial pathogen associated with COPD. It also causes otitis and sinusitis. An important virulence factor of M. catarrhalis is the outer membrane protein Moraxella catarrhalis IgD-binding protein (MID). One part of the protein; MID764-913 , has been shown to function as an adhesin, and this part has been fragmented to further investigate its adhesive properties. The aim of this second, independent study, was to express some of these proteinfragments by cloning in E. coli. The time spent on this project was too short, and no proteins could be expressed duing this period.</p>
13

Establishment, identification, quantification of methanogenic archaea in chicken ceca and methanogenesis inhibition in in vitro chicken ceca by using nitrocompounds

Saengkerdsub, Suwat 16 August 2006 (has links)
In the first phase of this study, the diversity of methanogenic bacteria in avian ceca was found to be minimal. Based on 16S rDNA clone libraries, a common phylotype, designated CH101, ranged between 92.86 to 100 % of the total clones whereas less than 1% of the other phylotypes were found. On the basis of the sequence identity, all of the sequences, except sequence CH1270, are related from 98.97 to 99.45% to 16S rDNA Methanobrevibacter woesei GS. Sequence CH1270 is 97.62% homologous to the sequence identified to uncultured archaeon clone ConP1-11F. Clearly, the predominant methanogen found to reside in the chicken ceca was M. woesei. By using a MPN enumeration method, methanogen counts were found to be in the range of 6.38 to 8.23 log10 organisms per gram wet weight. The 16S rDNA copy number per gram wet weight in the samples was between log10 5.50 and 7.19. The second phase of the study was conducted to observe the effects of selected nitrocompounds and two different feedstuffs on in vitro methane production in chicken cecal contents and rumen fluid. Initially, one of the three nitrocompounds was added to incubations containing cecal contents from laying hens supplemented with either alfalfa or layer feed. Both feed materials influenced volatile fatty acids (VFA) production and also fostered methane production in the incubations although methane was lower (P < 0.05) in incubations with added nitrocompound, particularly nitroethane. Secondly, nitroethane was examined in incubations of bovine or ovine rumen fluid or cecal contents containing either alfalfa or layer feed. Unlike cecal contents, layer feed significantly (P < 0.05) supported in vitro methane production in incubations of both rumen fluids. The results show that nitroethane impedes methane production, especially in incubations of chicken cecal contents. The final phase of this study was carried out to determine the methanogenic establishment in the chicken ceca by the cultural method with the quantitative PCR. The results suggested that methanogens colonized in chicken ceca at a few days after birth. Litter and house flies could be potential sources for methanogenic colonization in broiler chicks.
14

Systematics and Characterization of Purple Nonsulfur Bacteria in Lotus Pond

Lin, Hsiu-Ping 23 June 2004 (has links)
Purple nonsulfur bacteria are a group of extraordinary metabolic diverse bacteria. They can grow photoautotrophically, photoheterotrophically , chemoheterotrophically or chemoautotrophically. Under various conditions, they can enjoy exceptional flexibility within each of these modes of metabolism. Due to the special physical characteristics properties, they had attracted scientist¡¦s attention in resent years. These bacteria are widely distributed in nature such as lakes, water ponds, coastal lagoons or high concentration organic waste lagoons. Lotus Pond, located in northern Kaohsiung City, is a serious eutrophied artificial lake. Because of receiving sufficient light and having been polluted by significant amounts of soluble organic matter, the ecology of the lake is suitable for the growth of purple nonsulfur bacteria. In the study, the lake water and sediments by using a Winograsdsky column, we successfully isolated 16 strains bacteria from the Lotus Pond. We also amplified the 16S-rDNA fragments of these strains by PCR and sequenced these PCR products, then aligned these sequences with the data of GeneBank. We affirmed that the 16 isolated strains belong to purple nonsulfur bacteria. From phylogenetic analysis, these 16 strains belong to the following three groups of bacteria: Rhodopseudomonas palustris, Rubrivivax gelatinosus, and Rhodobacter sphaeroides. Characteristic studies of these strains, we found that all isolated strains are Gram negative bacteria and contain bacteriochlorophyll a. The strains that belong to R. palustris and R. sphaeroides group can use several different types of short chain organic acid as their carbon source and have denitrification ability. However, only the strains belong to R. palustris group are able to use the aromatic compound benzoate. From salt tolerant studies, we found the strains in R. sphaeroides group can grow well in 3% NaCl, and both R. palustris and R. gelatinosus group can only grow in 1% NaCl.
15

Establishment, identification, quantification of methanogenic archaea in chicken ceca and methanogenesis inhibition in in vitro chicken ceca by using nitrocompounds

Saengkerdsub, Suwat 16 August 2006 (has links)
In the first phase of this study, the diversity of methanogenic bacteria in avian ceca was found to be minimal. Based on 16S rDNA clone libraries, a common phylotype, designated CH101, ranged between 92.86 to 100 % of the total clones whereas less than 1% of the other phylotypes were found. On the basis of the sequence identity, all of the sequences, except sequence CH1270, are related from 98.97 to 99.45% to 16S rDNA Methanobrevibacter woesei GS. Sequence CH1270 is 97.62% homologous to the sequence identified to uncultured archaeon clone ConP1-11F. Clearly, the predominant methanogen found to reside in the chicken ceca was M. woesei. By using a MPN enumeration method, methanogen counts were found to be in the range of 6.38 to 8.23 log10 organisms per gram wet weight. The 16S rDNA copy number per gram wet weight in the samples was between log10 5.50 and 7.19. The second phase of the study was conducted to observe the effects of selected nitrocompounds and two different feedstuffs on in vitro methane production in chicken cecal contents and rumen fluid. Initially, one of the three nitrocompounds was added to incubations containing cecal contents from laying hens supplemented with either alfalfa or layer feed. Both feed materials influenced volatile fatty acids (VFA) production and also fostered methane production in the incubations although methane was lower (P < 0.05) in incubations with added nitrocompound, particularly nitroethane. Secondly, nitroethane was examined in incubations of bovine or ovine rumen fluid or cecal contents containing either alfalfa or layer feed. Unlike cecal contents, layer feed significantly (P < 0.05) supported in vitro methane production in incubations of both rumen fluids. The results show that nitroethane impedes methane production, especially in incubations of chicken cecal contents. The final phase of this study was carried out to determine the methanogenic establishment in the chicken ceca by the cultural method with the quantitative PCR. The results suggested that methanogens colonized in chicken ceca at a few days after birth. Litter and house flies could be potential sources for methanogenic colonization in broiler chicks.
16

Molecular phylogeny of Thatcheria mirabilis and the Superfamily of Conoidea

Lai, Jeng-ren 21 November 2009 (has links)
The taxonomic status of the Japanese Wonder Shell, Thatcheria mirabilis is questionable, because it has been classified in the family of Thatcheriidae, Turridae or Conidae (Superfamily: Conoidea). Conoidea is a large and diverse superfamily with more than 10,000 species. Based on shell and radula characters, it is classified into three families, i.e. Conidae, Terebridae and Turridae. However, seven families have been proposed based on foregut structure, shell and radula morphology. In the present study, the molecular phylogeny of Conoidea and the taxonomic status of Thatcheria mirabilis were determined by mitochondria DNA 16S rDNA. The results show that Conoidea includes three clades, presuming Conidae, Terebridae and Turridae. The mean genetic distances within clades were 0.12, 0.10 and 0.10, respectively. And, the distances between clades were 0.14~0.17. Phylogenetic trees reveal that Terebridae and Turridae were within the same group or sister group, Terebridae was closer to Turridae than to Conidae. Although Thatcheria mirabilis and Bathytoma luhdorfi have turrid-form shells, their phylogenetic relationship was close to Conus which was in Conidae`s clade. Some other species, i.e. Oenopota sagamiana¡BPhymorhynchus buccinoides and Raphitoma linearis were also in Conidae`s clade which had been placed in Turridae. In general, the results are consistent with the cladistic classification by Taylor et al (1993), Rosenberg (1998) and Bouchet & Rocroi (2005), but differenrt from the classification by Powell (1966) and Kohn (1998) based on shell characters. Additionally, the hollow, harpoon-like teeth and venom apparatus in Conoidea might independently evolve in each family.
17

Impact of simple and complex substrates on the composition and diversity of microbial communities and the end-product synthesis

Kumaravelayutham, Preethi 19 August 2015 (has links)
The effect of simple and complex on the composition and diversity of microbial communities and on end-product (biogas and VFAs) synthesis was investigated using an anaerobic batch respirometer at 37 °C and pH 7.2. These experiments, simple substrates were chemically pure and contain a single carbon source (glucose or α-cellulose), while complex substrates were chemically “impure” substrates containing a mixture of two or three carbon sources (biodiesel-derived glycerol or wheat straw) with a substrate/inoculum ratio 6g chemical oxygen demand (COD)/ g volatile solids (VS) seed and 100g of pre-treated dairy manure digestate (DMD), respectively. Concentrations of hydrogen, carbon dioxide, acetate, butyrate, propionate, and ethanol synthesized by different communities selected by growth on the different substrates were measured and confirmed the growth of the microbial communities. 16S rDNA illumina sequencing revealed that DMD without substrates was more diverse than the microbiota cultured by fermentation reactions containing D-glucose, glycerol α-cellulose or wheat straw. The data confirmed that substrates play a crucial role in determining the diversity of species in microbial communities. Dominant operational taxonomic units (OTUs) belonging to families Clostridiaceae, Ruminococcaceae, and Enterobacteriaceae, and the genera Clostridium, Ruminococcus, Sporolactobacillus, and Syntrophomonas were potentially responsible for changes in end-product synthesis patterns in communities cultured with simple and complex substrates. / October 2015
18

Características moleculares e identificação de Lactobacillus delbrueckii UFV H2b20 / Molecular characterization and identification of Lactobacillus delbrueckii UFV H2b20

Neves, Juliana Teixeira de Magalhães 20 February 2003 (has links)
Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-06-13T18:17:32Z No. of bitstreams: 1 resumo.pdf: 17263 bytes, checksum: 8e51a65fe7d8eecb448411acb64cf05b (MD5) / Made available in DSpace on 2017-06-13T18:17:32Z (GMT). No. of bitstreams: 1 resumo.pdf: 17263 bytes, checksum: 8e51a65fe7d8eecb448411acb64cf05b (MD5) Previous issue date: 2003-02-20 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / A estirpe probiótica Lactobacillus UFV H2b20, previamente classificada como Lactobacillus acidophilus por suas características de fermentação de açúcares, apresentou-se mais semelhante à espécie Lactobacillus delbrueckii, quanto à seqüência de rDNA 16S, o que levou ao questionamento acerca da identidade da linhagem. Para o esclarecimento da real classificação da linhagem, o método de hibridização DNA-DNA foi empregado. A linhagem apresentou 75,2% e 77,4% de reassociação com L. delbrueckii subsp. lactis (ATCC 12315) e L. delbrueckii subsp. delbrueckii (ATCC 9649), respectivamente. Dado que a homologia de 70% ou mais, por esse método, tem sido usada como padrão para agrupamento de bactérias em uma mesma espécie, sugere-se, aqui, que Lactobacillus UFV H2b20 seja, daqui para frente, denominado L. delbrueckii UFV H2b20. Identificada a linhagem, outro objetivo do trabalho era desenvolver um protocolo para detecção in situ de L. delbrueckii. Uma sonda de 26 nucleotídeos (SA) foi construída e testada com outras espécies de Lactobacillus relacionadas geneticamente entre si. Estes estudos demonstraram que a seqüência de assinatura (SA) estava presente em L. delbrueckii UFV H2b20, L. delbrueckii UFV H2b21, L. delbrueckii subsp. delbrueckii e L. delbrueckii subsp. lactis, o que indica ser ela eficaz para ser usada como sonda para rRNA 16S espécie-específica pelo método de FISH. A hipótese de existência de polimorfismos, levantada em trabalhos prévios no rDNA 16S da linhagem, foi confirmada após as análises dos segmentos de DNA clonados e selecionados do banco genômico construído para a linhagem L. delbrueckii UFV H2b20. As seqüências analisadas demonstraram, também, presença de segmentos correspondentes a quatro genes codificadores de rRNA 16S distintos, e seis segmentos distintos para uma mesma região de rRNA 23S, indicando seis operons putativos. Há evidência de, pelo menos, um operon putativo completo seguido de região codificadora de seis tRNAs. Não se detectou região espaçadora longa entre rDNA 16 e 23S. / Lactobacillus UFV H2b20, a probiotic strain, previously identified as Lactobacillus acidophilus due to its sugar fermentation pattern, was found to be more closely related to Lactobacillus delbrueckii regarding its 16S rDNA sequence. It was demonstrated by DNA-DNA hybridization that this strain presented 75.2% and 77.4% of reassociation with L. delbrueckii subsp. lactis ATCC 12315 and L. delbrueckii subsp. delbrueckii ATCC 9649, respectively. These results place Lactobacillus UFV H2b20 within the L. delbrueckii species, for 70% reassociation as measured by the method used has been a standard to cluster bacteria within the same species. A protocol for in situ detection of L. delbrueckii was developed by means of Fluorescent in situ Hybridization, FISH. A probe consisting of 26 nucleotides labeled with rhodamine was designed based on the signature sequence within the rDNA, and was tested against genetically related Lactobacillus species. A species- specific method was obtained capable of discriminating L. delbrueckii strains from other Lactobacillus species. Previous studies raised the hypothesis of polymorphism among the copies of 16S rDNA in L. delbrueckii UFV H2b20. This was confirmed by sequence analysis of rDNA from a gene library of this strain cloned in phage lambda and subcloned in pBluescript. Sequence analyses of cloned fragments demonstrated the presence of at least four distinct genes encoding 16S rRNAs. Distinct fragments containing 23S rRNA related genes indicated six putative rrn operons. One complete putative rrn operon displays a region encoding 6 different tRNAs. Long spacer regions between 16S and 23S rDNA were not detected.
19

Potencial biotecnológico de actinobactérias da coleção UFPEDA contra Candida spp

SANTANA, Raphael Carlos Ferrer de 24 February 2015 (has links)
Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-06-30T16:59:18Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação- Raphael Santana.pdf: 1198352 bytes, checksum: 2ddd13ab9df70bdaf76d80dd5d481f49 (MD5) / Made available in DSpace on 2016-06-30T16:59:19Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação- Raphael Santana.pdf: 1198352 bytes, checksum: 2ddd13ab9df70bdaf76d80dd5d481f49 (MD5) Previous issue date: 2015-02-24 / FACEPE / Actinobactérias são bactérias Gram-positivas formadoras de filamentos ramificados que se destacam pela produção de metabólitos secundários, como antimicrobianos, antitumorais, fitohormônios e corantes naturais. Diante disso, este trabalho teve o objetivo de determinar o potencial biotecnológico de actinobactérias da coleção UFPEDA contra Candida spp. Para avaliação da atividade biotecnológica, 32 actinobactérias foram testadas contra sete isolados clínicos de Candida spp. utilizando diferentes meios de cultura para o crescimento (ALA, ISP-4, AY, ISP-3) e temperaturas (37 ºC ou 45 ºC). No ensaio primário, foi evidenciada atividade apenas quando as actinobactérias foram cultivadas em meio ISP-3 a temperatura de 37 ºC. Dessas, apenas 2 linhagens (6,25 %) apresentaram atividade antifúngica com halo de inibição variando entre 11 mm e 18 mm. As duas linhagens produtoras de metabólitos secundários com atividades antifúngicas não apresentaram diferença estatística, por isso foi selecionada a linhagem G24 por apresentar um pigmento na cor vermelha para dar seguimento às análises. A fermentação da linhagem (G24) foi realizada para avaliar atividade antifúngica, biomassa e pH, durante 5 dias, utilizando diferentes meios (MPE, M1 e ISP-3),sendo tais parâmetros monitorados a cada 24 horas. O melhor meio para produção de metabólitos secundários foi ISP-3 fermentado durante 48 h em pH 7.0, sendo evidenciados halos de inibição de 13 a 18 mm e biomassa de 0,1 g/mL de meio. Estabelecidas às condições, foi realizada a extração do princípio bioativo, sendo evidenciada atividade apenas para biomassa quando extraído em acetato de etila. A concentração mínima inibitória (CMI) do extrato bruto variou de 125 μg/mL a 62,5 μg/mL para Candida spp testadas. Análise Cromatográfica do Extrato Bruto as frações semi-purificadas foram analisadas por cromatografia em camada delgada (CCD) sendo evidenciadas duas frações, uma com atividade antifúngica e outra um corante natural. As características morfológicas do isolado G24 foram analisadas por microscopia óptica, sendo observados esporos verticilados pertencente ao gênero Streptomyces. O gene 16S rDNA foi amplificado e enviado para sequenciamento, sendo identificada como Streptomyces sp. Diante destes resultados, podemos concluir que a linhagem (Streptomyces sp), isolado da rizosfera de Caesalpinia pyramidalis tul, do bioma Caatinga, apresenta uma significativa atividade antifúngica e necessita de estudos espectroscópios para caracterização do composto bioativo e do corante. / Actinobacteria are forming Gram-positive bacteria of branched filaments that stand out for the production of secondary metabolites such as antibiotics, antitumor, phytohormones and naturias dyes. Given this, this study aimed to determine the biotechnological potential of actinomycetes of UFPEDA collection against Candida spp. To evaluate the biotechnological activity, 32 actinomycetes were tested against seven clinical isolates of Candida spp., Using different culture media (ALA, ISP-4, AY, ISP-3) and temperatures (37 ° C and 45 ° C). In the primary test, activity was detected only when the actinomycetes were grown in ISP-medium 3 to a temperature of 37 ° C. Of these, only 2 strains (6.25%) showed antifungal activity with inhibition zone ranging between 11 mm and 18 mm. Fermentation of strain (G24) was used to evaluate antifungal activity, biomass and pH for 5 days, using different media (MPE M1 and ISP-3), these parameters being monitored every 24 hours. The best medium for production of secondary metabolites ISP-3 was fermented for 48 h at pH 7.0, being evidenced inhibition zones 13 to 18 mm and biomass of 0.1 g / ml medium. Established conditions, the extraction of bioactive principle has been performed and demonstrated activity only when biomass extracted into ethyl acetate. The minimum inhibitory concentration (MIC) of the crude extract ranged from 125 mg / mL to 62.5 mg / mL for Candida spp tested. In chemical prospecting, semi-purified fractions were analyzed by thin layer chromatography (TLC) was evidenced two fractions, one with antifungal activity and one with a natural dye. The morphological characteristics of isolated G24 were analyzed by optical microscopy, observed verticilados spores belonging to the genus Streptomyces. The 16S rDNA gene was amplified and sent to sequencing, being identified as Streptomyces sp. Given these results, we can conclude that the line (G24) (Streptomyces sp), isolated from the rhizosphere of Caesalpinia pyramidalis tul, the Caatinga biome, presents a significant antifungal activity and requires spectroscopes studies to characterize the bioactive compound and the dye.
20

The Molecular Analysis of the Biofilm of Proximal Incipient Caries in Young Permanent Teeth

Fishman, Ross H. 09 September 2009 (has links)
No description available.

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