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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.
101

Estudo de sete espécies de Rhodnius (Hemiptera, Reduviidae, Triatominae) por meio de dois genes nucleares e um mitocondrial

Ferreira Filho, Júlio César Rente [UNESP] 26 July 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-26Bitstream added on 2014-06-13T20:36:32Z : No. of bitstreams: 1 ferreirafilho_jcr_me_arafcf.pdf: 627816 bytes, checksum: b1c11f69fc69c2ac25f9a07f076cafa8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Os membros da subfamília Triatominae são vetores do protozoário Trypanosoma cruzi, agente etiológico da doença de Chagas. Eles compreendem 144 espécies agrupadas em 18 gêneros e são encontrados principalmente nas Américas, desde o sul dos Estados Unidos ao sul da Argentina e Chile. Essencialmente a identificação desses insetos tem sido baseada na descrição comparativa da morfologia de indivíduos adultos incluindo as estruturas da genitália masculina e feminina, aspectos gerais do corpo como cabeça, tórax, antena e coloração, entre outros. Entretanto a distinção por critérios morfológicos apresenta limitações para caracterização de espécies do gênero Rhodnius devido às semelhança entre elas, especialmente entre R. prolixus, R. domesticus, R. robustus, R. neglectus, and R. nasutus, espécies conhecidas como “grupo prolixus”. Nesse estudo as técnicas de biologia molecular, sequenciamento do gene 16S e PCR-RFLP, foram utilizados para caracterização de sete espécies de Rhodnius. Os produtos do sequenciamento do gene 16S das espécies R. brethesi; R. nasutus, R. nasutus, R. neglectus, R. pictipes; R. prolixus, R. robustus, e R. sp geraram alinhamento de 380 pares de bases com 48 sítios polimórficos. A visualização das bandas geradas pelas enzimas de restrição BstUI, HhaI, RsaI and Mbol com as sete amostras de Rhodnius possibilitou distingui-las com exceção de R. prolixus, R. neglectus e R.robustus. Os dois métodos feitos para as mesmas amostras confirmaram a validade da utilização do método PCR-RFLP para identificação de R. brethesi, R. nasutus, R. pictipes e R. sp, uma vez que o gene 16S já é um marcador estabelecido para as espécies de Rhodnius e as duas metodologias apresentaram os mesmos resultados, confirmaram também o trabalho realizado por Naegele et al. 2006 em que a técnica de PCR-RFLP distinguiu R. stale, R. pictipes, R. Prolixus and R. domesticus / The members of the subfamily Triatominae are vectors of the protozoan Trypanosoma cruzi, which is the etiologic agent of Chagas disease. They consist of 144 species grouped into 18 genera and are found mainly in the Americas, from the southern United States to southern Argentina and Chile. Essentialy, the identification of these insects has been based on the comparative description of the morphology of adult specimens, including the structures of both the male and female genitalia, general body features like head, thorax, antennae and color, among others. However, this method is not particularly useful in the characterization of species belonging to the genus Rhodnius because they are very similar morphologically, specially R. prolixus, R. domesticus, R. robustus, R. neglectus, and R. nasutus, which are known as “prolixus complex”. In this study molecular biology techniques, such as sequencing of 16S gene and PCR-RFLP, was used to contribute to the characterization of seven species of Rhodnius. The products of the sequencing of the 16S species R. brethesi; R. nasutus, R. nasutus, R. neglectus, R. pictipes; R. prolixus, R. robustus, and R. sp generated a alingment of 380bp with 48 polymorphic sites. The visualization of the bands arising from the use of restriction enzymes BstUI, HhaI, RsaI and Mbol with samples of seven species of Rhodnius possible to distinguish them except for R. prolixus, R. neglectus and R.robustus. The two methods performed in parallel for the same samples confirmed the validity of using the enzymatic method for specific identification of R. brethesi, R. nasutus, R. pictipes e R. sp, since the 16S gene is already an established marker for it and the two methods showed the same results, confirmed too the work performed by Naegele et al.2006 that the PCR-RFLP technic distinguished R. stale, R. pictipes, R. Prolixus and R. domesticus
102

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.
103

Comunidades de arquéias metanogênicas em diferentes usos dos solos da Amazônia / Communities of methanogenic archaeas in different uses of Amazonian soils

Kelly Jaqueline Alves 12 January 2018 (has links)
A conversão de áreas de florestas da Amazônia em áreas agrícolas e pastoris desregula processos relacionados ao estoque de carbono, sendo considerada depois da queima de combustíveis fósseis a atividade que mais contribui com a emissão de gases do efeito estufa, dentre os quais se encontra o metano. A produção de metano é intermediada pelas arquéias metanogênicas, que atuam na decomposição anaeróbia da matéria orgânica. Portanto, para compreender as alterações do fluxo desse gás no ecossistema amazônico, é necessário que as comunidades microbianas envolvidas nesse processo sejam estudadas. Dessa forma, o presente estudo teve por objetivo monitorar e caracterizar comunidades de arquéias metanogênicas, por análises de enriquecimento destas comunidades, em amostras de solo provenientes de floresta primária, floresta secundária e pastagem da região amazônica. As amostras de solo foram colocadas em meio enriquecido com a adição de acetato, metanol ou H2:CO2, separadamente, para estimular os metabolismos aceticlástico, metilotrófico e hidrogenotrófico. O monitoramento desses cultivos foi realizado por análises de emissão de metano por cromatografia gasosa, quantificação do gene mcrA pela técnica de PCR quantitativo (qPCR) e caracterização da comunidade metanogênica por meio de microscopia e sequenciamento da região V4-V5 do gene 16S rRNA. Analisando a emissão de metano entre os três tipos de fontes de carbono para as três amostras de solo, os enriquecimentos com metanol apresentaram uma produção maior de metano em relação as amostras com o acetato e muito superior aos cultivos com atmosfera de H2:CO2. A maior média de produção de metano ocorreu nos enriquecimentos com metanol, indicando que a via metilotrófica embora considerada alternativa, pode ser importante na produção de metano no solo amazônico. Por meio da técnica de qPCR foi possível quantificar o gene mcrA das amostras de pastagens logo no tempo inicial da incubação, o que não foi possível para as amostras florestais. No tempo final, o número de cópias desse gene foi similar para os três perfis de solo. Foi possível observar pela caracterização fenotípica dos enriquecimentos agregados de células característicos do gênero Methanosarcina, gênero que foi identificado posteriormente pelo sequenciamento do gene 16S rRNA, além de células em formatos de bastonetes e cocos. Os resultados do sequenciamento permitiram identificar 7 grupos distintos de arqueias metanogênicas, afiliados aos filos Euryarchaeota e Bathyarchaeota. Nas amostras iniciais de pastagens foram identificadas sequências que se afiliaram a todos esses grupos, enquanto as amostras florestais apresentaram sequencias afiliadas apenas ao gênero Methanosarcina. A composição final da comunidade das amostras de pastagens foi similar a inicial, porém mais abundante. Os enriquecimentos de amostras de solo de floresta primária e secundária apresentaram uma composição distinta, devido ao enriquecimento de grupos que não foram identificados no início da incubação. Os resultados obtidos mostraram que embora as arqueias metanogênicas estejam em baixa abundância nos solos florestais, podem ser enriquecidos quando submetidos a condições favoráveis, atingindo produção de metano e alcançando composição similar as amostras de pastagens. / Amazonian forest conversion into agricultural and livestock areas disrupts processes related to carbon stock, being considered, after the fossil fuels burning, the activity contributes most to greenhouse gases emission, of which is methane. Methane production is mediated by methanogenic archaea, acting in organic matter anaerobic decomposition. Therefore, to understand the changes in the flow of this gas in the Amazonian ecosystem, it is necessary to study microbial communities involved in this process. This study aims to monitor and characterize methanogenic archaeal communities by population enrichment from soil samples collected in primary, secondary and pasture of the Amazon region. Soil samples were placed into an enriched medium and received separately acetate, methanol, and H2:CO2 to stimulate the three metabolism types: acetoclastic, methylotrophic and hydrogenotrophic. Monitoring was performed by methane emission analysis by gas chromatography, mcrA quantification by the quantitative PCR and the community characterization was performed by microscopy and sequencing of the V4-V5 region of the 16S rRNA gene. Analyzing the methane emission by the three types of carbon sources in the three soil samples, methanol enrichments presented a higher methane yield than the acetate samples and much larger than cultures with H2:CO2. These results indicate that methylotrophic pathway, although considered as an alternative, may be important in methane production in the Amazonian soil. Was possible to quantify the mcrA gene by qPCR from pasture samples at the initial incubation time, which was not possible for forest samples. In incubation final time, copies number of this gene was similar for the three soil profiles. The phenotypic characterization of enrichments revealed aggregated cells, characteristic of the genus Methanosarcina, later identified by 16S rRNA sequencing. The cells in rod-shaped and cocci formats were also observed. Was identify by sequencing 7 different methanogenic archaeas groups affiliated with Euryarchaeota and Bathyarchaeota phylum. In the initial pasture samples, were identified sequences affiliated with all these groups, while forest samples presented sequences affiliated with only a Methanosarcina genus. Pasture samples showed a final community composition similar to initial, however more abundant. Soil samples enrichment from primary and secondary forest presented a distinct composition due to groups enrichment that was not identified at incubation beginning. These results showed that although methanogenic archaeas are in low abundance in forest soils, they can be enriched when submitted to favorable conditions, archive methane production and reaching similar composition pasture samples.
104

The unseen world of coral reefs: impact of local and global stressors on coral microbiome community structure

McDevitt-Irwin, Jamie 04 May 2017 (has links)
Diverse and abundant coral associated microbial communities may play a key role in coral resistance to and recovery from unwavering stressors currently threatening coral reefs worldwide. The composition and structure of the coral microbiome is integral to coral health as microbes can play beneficial (e.g. nutritional or protective) or negative (e.g. pathogenic or opportunistic) roles in the coral. To review the impacts of stressors on the coral microbiome, I compiled data from 39 studies, each tracking microbial community shifts in corals experiencing stress from climate change, pollution or overfishing. Stress was associated with shifts in coral microbial communities. I found that regardless of stressor, microbial alpha diversity increased under stress, with Vibrionales, Flavobacteriales and Rhodobacterales commonly found on stressed corals, and Oceanospirillales not as abundant on stressed corals. In addition, I used 16S rRNA sequencing to evaluate how local and global stressors affect the community structure of the coral microbiome for the two coral species, Porites lobata and Montipora foliosa. I monitored tagged coral colonies at two human disturbance levels (i.e. high and low), before and during a thermal bleaching hotspot at Kiritimati, Kiribati. Human disturbance, a bleaching hotspot, and coral species were all important drivers of coral microbiome community structure. My results suggest that human disturbance increases microbial alpha and beta diversity, although results vary between coral species, with P. lobata having more of a difference between disturbance levels. Similarly, bleaching increased beta diversity at low disturbance sites. Both human disturbance and thermal stress appeared to homogenize coral microbiomes between species and thermal stress appeared to homogenize communities between disturbance levels. Thus, both human disturbance and bleaching appear to stress the coral and destabilize its microbiome. However, intense thermal stress (i.e. 12.86 DHWs) appears to have a greater influence than human disturbance, probably due to corals responding to stressful conditions in a similar manner. In conclusion, my results highlight the impact of local and global stressors on coral microbiome community structure. / Graduate / 2018-04-26 / 0359
105

Ecology and diversity of freshwater picocyanobacteria in Japanese lakes / 日本湖沼に生息する淡水性ピコシアノバクテリアの生態と多様性

Cai, Ji 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23041号 / 理博第4718号 / 新制||理||1676(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 中野 伸一, 教授 曽田 貞滋, 教授 木庭 啓介 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
106

Characterization of the Bioluminescent Symbionts from Ceratioids Collected in the Gulf of Mexico

Freed, Lindsay L 19 June 2018 (has links)
Anglerfishes are easily one of the most popular deep-sea creatures due to their menacing appearance, extreme sexual dimorphism, parasitic mating approach, and eye catching bioluminescent lure. Unlike most bioluminescent fishes, which intrinsically generate light, female anglerfishes belonging to nine of the 11 families within the suborder Ceratioidei (deep-sea anglerfishes) have developed a symbiotic relationship with bioluminescent bacteria that are housed within the light organs. Previous molecular work had identified symbionts from two anglerfish species as novel and possibly unculturable taxa (Haygood et al., 1992), but nothing more has been revealed about the bioluminecent symbionts of ceratioids. As part of the Gulf of Mexico Research Initiative-funded DEEPEND project (Deependconsortium.org), the objective of this study is to characterize the escal microbiome of deep-sea anglerfishes and identify potential-symbiont taxa. A total of 36 anglerfish specimens were collected on DEEPEND cruises DP01 through DP04. These specimens consist of adult and larval individuals belonging to six of the families with the suborder Ceratioidei: Ceratiidae (n=22), Oneirodidae (n=7), Linophrynidae (n=3), Melanocetidae (n=2), Centrophrynidae (n=1), Melanocetidae (n=2), Gigantactinidae (n=1). DNA was extracted from esca, skin, fin, gill, gut, and caruncle tissues, as well as seawater. High-throughput sequencing of the 16S rRNA hypervariable V4 region was carried out using the Illumina MiSeq. Sequencing revealed five potential bioluminescent-symbiont taxa (OTU IDs: 9129, 9131, 160210, 523223, and 939811), which had the greatest relative abundance (25.2% - 98.7%) within 12 of 21 adult specimens. These taxa belong to the family Vibrionaceae and were found at greater than 10% relative abundance in the escal samples of adult anglerfishes belonging to the Ceratiidae and Melanocetidae families, but they were not found in high abundance in larval individuals of the same families. Sequencing of larval samples revealed five potential bioluminescent-symbiont taxa (OTU IDs: 136178, 176420, 523223, 837366, 939811) which were of greatest relative abundance (8.1%-67.1%) within nine of 13 specimens. Also members of the family Vibrionaceae, these taxa were found in high abundance in larval anglerfishes belonging to the Oneirodidae, Linophrynidae, Gigantactinidae, and Ceratiidae families. This study is the first to to examine the bioluminescent symbionts from seven different ceratioid families.
107

Bacterial community dynamics during lignocellulose decomposition as affected by soil and residue types

Michel, Himaya Mula 30 April 2011 (has links)
This study was conducted to determine dynamics of bacterial communities during decomposition and to find out whether the occurrence of bacterial communities was affected by soil and residue types. It was hypothesized that there would be a shift in bacterial community structure during decomposition. Also, distinct microbial communities in different two soils associated with two residues would result in colonization by different microbial taxa. The first hypothesis was based on expected changes in the composition of decomposing residues. The second hypothesis was based on the fact that soil microbial diversity is soil-specific and immense with numerous different functionally redundant but phylogeneticaly different microbial types. Residues with different chemical properties were also expected to affect bacterial community composition, however, its impact would be lesser compared to soil. A 2 x 2 x 4 factorial experiment was conducted consisting of switchgrass (Panicum virgatum) and rice (Oryza sativa) straw; 2 soil types (Sharkey and Marietta series); and 4 incubation periods (3, 23, 48 and 110 days). Clone libraries of the bacterial communities were constructed from the detritusphere (residues and adhering soil). Non-metric multidimensional scaling of the detritusphere communities showed distinct separation of the communities at day 3 which coincided with high levels of cellulase enzyme activity and reduction of soluble carbon. style='mso-spacerun:yes'> Availability of labile carbon appeared to be important in driving bacterial community succession at early stage of colonization. During the later stages of decomposition (day 23-110), bacterial communities were segregated into two groups according to soil type. Although important, this segregation was relatively small compared to the community-level similarities observed between the soils and residues. For example, 16 of the 22 most abundant OTU's, dominated by a-,b- and style='fontamily:Symbol'>g- Proteobacteria, Bacilli and Shingobacteria, were shared among all soil and residue treatments indicating that residue decomposition is carried out by few key-player taxa. These results run counter to our hypothesis and suggest that decomposition process may be mediated by certain domineering bacterial taxa which occur at the later stage of decomposition. Further research is needed to determine whether key functional ecosystem processes are dominated by only a few taxa despite taxonomically hyper-diverse soils.
108

Identifiering av 13 nya mjölksyrabakterier med DHPLC

Livaja, Ruzica January 2011 (has links)
Mjölksyrabakterier tillhörande släkten Lactobacillus och Bifidobacterium har nyligen upptäckts hos bin och i honungen de producerar och innefattar 13 nya arter[1]. Forskarna arbetar med att ta fram nya snabba och mer pålitliga identifierings metoder för att karakterisera dessa bakterier.I detta projekt undersöktes möjligheten att identifiera dessa bakterier med en ny metod som heter denaturing high performance liquid chromatography (DHPLC). Metoden bygger på separation av PCR (polymerase chain reaction) amplifierade 16S rDNA fragment i DHPLC [8]. Vid identifiering av bakterier amplifierades olika variabla regioner från 16S rRNA genen, som påvisade efter sekvensering störst genetisk variation mellan dessa bakterier [1]. Separationen utfördes med ion-pair reverse-phase high presure liquid chromatoghaphy (IP RP HPLC) med delvis denaturering av DNA molekylen. Tidigare studier av identifiering av marina bakterier med DHPLC resulterade i optimal separation [9]. Identifiering av följande mjölksyrabakterier kunde verifieras till en viss grad. Analys i DHPLC visade profiler med urskiljbara toppar som utgjorde separation på artnivå, detta enbart mellan två bakterier tillhörande släktet Lactobacillus. Trots olika justeringar av analys parametrar gällande kolonntemperatur och elueringsbuffert, erhölls inte separation mellan alla 13 arter. Analysen kan ha påverkats av en rad olika funktionsfel i HPLC systemet och felaktig beredning av prov. Metoden kunde eventuellt förbättrats om tiden inte varit en begränsning. / Lactic acid bacteria belonging to genera Lactobacillus and Bifidobacterium has been recently discovered in bees and the honey they produce, and includes 13 new species [1]. Researchers are working to develop new rapid and more reliable detection methods to characterize these bacteria.In this project we investigate the possibility of identifying these bacteria with a new method called denaturing high performance liquid chromatography, DHPLC. The method involves the separation of the PCR (polymerase chain reaction) amplified 16S rDNA fragments in the DHPLC [8].For the identification of bacteria various variable regions of 16S rRNA gene was amplified, sequencing proved great genetic variability between these bacteria [1]. Separation is effected by means of ion-pair reverse-phase high pressure liquid chromatography (IP RP HPLC) with partial denaturation of the DNA molecule.Previous studies of the identification of marine bacteria by DHPLC resulted in optimal separation [9]. Identification of the following lactic acid bacteria was verified to some limited degree. Analysis of the DHPLC demonstrated profiles with distinguishable peaks that represented the separation at the species level, that only between two bacteria of the genus Lactobacillus.Despite numerous adjustments of operating conditions such as existing column temperature and eluent buffer, did not result in separation of all 13 species. The analysis may have been influenced by a variety of malfunctions in the HPLC system and improper sample preparation. The method could possibly be improved if time was not a limitation.
109

Pathogenicity of Clostridium Perfringens and its Relationship with Gut Microbiota in Chickens

Yang, Wenyuan 14 December 2018 (has links)
Necrotic enteritis (NE), a devastating enteric disease caused by Clostridium perfringens type A, contributes to the losses of 6 billion dollars worldwide per year and is currently being considered as a major global threat to the poultry industry. In past decades, it has been well-controlled by ineed antimicrobial growth promoters (AGPs). The withdrawal of AGPs due to antibiotic-resistance concerns resulted in a spike in NE incidence and led to the re-emergence of NE in the modern broiler production system. To unveil the association of toxin genes of C. perfringens, particularly for netB, with clinical NE, a self-designed qPCR primer set targeting netB was developed to qualify and quantify netB in NE-producing and non-NE-producing isolates. The netB was demonstrated to exist in the majority of C. perfringens type A isolates. The presence and the amount of netB were not significantly different between two types of isolate, indicating that those indicators are insufficient to predict an association with the pathogenicity of NE. The virulence of netB is suggested to be expressed or triggered under certain conditions, further promoting NE. A side by side trial was implemented with different combinations of netB-positive C. perfringens (CP1) and two predisposing factors to assess their role in NE development. Both CP1 and predisposing factor(s) are required for consistent NE reproduction, and particularly, Eimeria exerts significant effects on NE induction. The use of CP1 without a predisposing factor failed to induce NE. The severity and incidence of NE were positively correlated with the number of predisposing factors given in the NE induction. Analyzing gut microbiota in chickens challenged with CP1 and/or Eimeria by metagenomic sequencing, significant overgrowth of Clostridium sensu stricto 1, the genus contains C. perfringens, was associated with NE. Eimeria infection precedent to CP1 challenge had a synergistic effect on the overrepresentation. In addition to C. perfringens, the other member under Clostridium sensu stricto 1 was found to participate in NE development. Given supplementary dose of 0.4 kg/ton in feed, lauric acid neither exerted the inhibitory effect against proliferation of Clostridium sensu stricto 1 and C. perfringens nor reduced the incidence and severity of NE.
110

PHOTOSYNTHETIC PICOPLANKTON AND BACTERIOPLANKTON IN THE CENTRAL BASIN OF LAKE ERIE DURING SEASONAL HYPOXIA

Cupp, Audrey R. 26 June 2006 (has links)
No description available.

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