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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.
1

Evaluating effects of southern yellow pine biochar and wood vinegar on poultry litter

Mohammadi-Aragh, Maryam 13 December 2019 (has links)
The objectives of this study were to investigate nutrient retention, intI1 prevalence, and compost maturity rates for poultry litter co-composted with 5, 10, and 20% southern yellow pine biochar and with or without 2% wood vinegar (WV). Samples were collected at 0, 57, and 112 days to measure nitrogen, phosphorus, and potassium (N, P, K) concentrations, microbial counts, pH, moisture content, carbon to nitrogen (C:N) ratio, and intI1 abundance. Composts were aerated once a week and the temperature was also recorded once a week. There was sufficient rainfall so no additional water was added. The results showed that N and P concentrations significantly increased over time in all treatments except 20% biochar and 20% biochar + wood vinegar, while K concentrations significantly decreased. In general, composting with wood vinegar significantly decreased nutrient concentrations; however, all nutrient concentrations were much higher than typical animal manure fertilizers. Increases in biochar level resulted in significantly lower bacteria counts and significantly higher fungi counts. Compost treatments containing wood vinegar had significantly lower bacteria and fungi counts, indicating that southern yellow pine wood vinegar had a biocide effect on microorganisms, and may be not suitable for composting at that application rate. intI1 prevalence was not significantly different among treatments, which may be due to insufficient thermophilic composting. Because thermophilic temperatures were not achieved, the compost was not mature by the end of the study; therefore, compost maturity rates could not be determined.
2

Suscetibilidade a antimicrobianos e genes de virulência em Salmonella enterica de origem avícola / Antimicrobials susceptibility and virulence genes in Salmonella enterica of avicultural origin

Oliveira, Aline Pedrosa de 22 December 2016 (has links)
Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-10-02T12:04:15Z No. of bitstreams: 2 Tese - Aline Pedrosa de Oliveira - 2016.pdf: 3128576 bytes, checksum: bbad449f3830d7359e905a2812b2a74e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-03T11:45:04Z (GMT) No. of bitstreams: 2 Tese - Aline Pedrosa de Oliveira - 2016.pdf: 3128576 bytes, checksum: bbad449f3830d7359e905a2812b2a74e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-10-03T11:45:04Z (GMT). No. of bitstreams: 2 Tese - Aline Pedrosa de Oliveira - 2016.pdf: 3128576 bytes, checksum: bbad449f3830d7359e905a2812b2a74e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-12-22 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Salmonella enterica is a foodborne pathogen with multifactorial and complex pathogenic mechanisms. Identification of the presence of virulence genes and antimicrobial resistance profiles in isolates of poultry origin provides relevant information on the risk attributed to the consumption of products contaminated by the agent. The objective of this study was to verify the susceptibility profile of Salmonella enterica for nalidixic acid (30μg), amicacin (30μg), ampicillin (10mg), ceftiofur (30μg), chloramphenicol (30μg), ciprofloxacin (5μg), enrofloxacin (5μg), streptomycin (10mg), gentamicin (10mg), tetracycline (30μg), tobramycin (10mg) and trimethoprim (5μg) used in both human and animal medicine, to investigate the presence of multiresistant isolates, to detect the presence of the variable region of the class 1 Integron, to analyze the association between the presence of Class 1 Integron and antimicrobial resistance and to evaluate the presence of virulence genes located in the islands of virulence 1 (invA) and 2 (sseD), gene encoding long polar fimbriae (lpfA) and plasmidial spvR, to identify the virulence profiles and pathogenicity potential of Salmonella enterica serovars isolated from carcasses, hearts, livers, gizzards and environment of slaughterhouses located in the State of Goiás and on chicken carcasses marketed in commercial establishments in Goiânia -GO. The highest resistance frequency was observed for ceftiofur, 19.12% (13/68), followed by streptomycin, gentamicin, tobramycin, tetracycline and trimetropic, 16.18% (11/68) both, nalidixic acid 14.71% (10/68), ampicillin 13.24% (9/68), and enrofloxacin 2,94% (2/68). No resistance was observed for ciprofloxacin, only intermediate, 45.59% (31/68), 100% (68/68) of the isolates were sensitive to amikacin and chloramphenicol. Of the 68 isolates 22 (32.35%) were resistant to one or more antimicrobial principles. Twelve profiles of antimicrobial resistance were identified, 54.54% (12/22) of the isolates presented multiresistance. The variable region of Class 1 Integron was detected in 63.23% (43/68) of the isolates. The presence of this region was not associated with antimicrobial resistance. All slaughterhouses and in most commercial establishments it was possible to identify Salmonella enterica carrying the Integron of class 1 demonstrating the ubiquity of the same. The invA gene was identified in 100% (59/59), sseD in 92.53% (54/59), lpfA in 86.51% (52/54) and spvR in 86.18% (49/59) of the serovars of Salmonella enterica. Six virulence profiles were identified, 77.97% of the isolates were grouped in profile A characterized by the presence of the four virulence genes simultaneously. The knowledge of the virulence profiles of the isolates allows to affirm that the serovars identified in the state of Goiás are potentially virulent and capable of triggering disease in poultry production systems and in humans. / Salmonella enterica é um patógeno de veiculação alimentar com mecanismos de patogenicidade multifatoriais e complexos. A identificação da presença de genes de virulência e de perfis de resistência a antimicrobianos em isolados de origem avícola fornece informações relevantes quanto ao risco atribuído ao consumo de produtos contaminados pelo agente. Pelo exposto, objetivou-se com este trabalho verificar o perfil de suscetibilidade de Salmonella enterica para ácido nalidíxico (30μg), amicacina (30μg), ampicilina (10mg), ceftiofur (30μg), cloranfenicol (30μg), ciprofloxacina (5μg), enrofloxacina (5μg), estreptomicina (10mg), gentamicina (10mg), tetraciclina (30μg), tobramicina (10mg) e trimetoprima (5μg), utilizados tanto na medicina humana quanto animal. Investigar a presença de isolados multirresistentes. Detectar a presença do Integron de classe e analisar a associação entre a presença deste e a resistência antimicrobiana. Ainda avaliar a presença de genes de virulência localizados nas ilhas de virulência 1 (invA) e 2 (sseD), gene codificador de fímbria polar longa (lpfA) e o plasmidial spvR em sorovares de Salmonella enterica isolados a partir de carcaças, corações, fígados, moelas e ambiente de abate de abatedouros localizados no estado de Goiás e em carcaças de frango comercializadas em estabelecimentos comerciais de Goiânia -GO. A maior frequência de resistência foi obervada para ceftiofur, 19,12% (13/68), seguido pelos antimicrobianos, estreptomicina, gentamicina, tobramicina, tetraciclina e trimetropima, 16,18% (11/68), ácido nalidíxico 14,71% (10/68), amplicilina 13,24% (9/68), e enrofloxacina 2,94% (2/68). Não foi observado resistência dos isolados para ciprofloxacina, sendo, 45,59% (31/68), considerados apenas intermediários. Entretanto, 100% (68/68) dos isolados foram sensíveis à amicacina e ao cloranfenicol. Dos 68 isolados, 22 (32,35%) foram resistentes a um ou mais princípios antimicrobianos. Foram identificados 12 perfis de resistência à antimicrobianos e 54,54% (12/22) dos isolados apresentaram multirresistência. A região variável do Integron de Classe 1 foi detectado em 63,23% (43/68) dos isolados. A presença desta região não apresentou associação com a resistência aos antimicrobianos. Em todos os abatedouros e na maioria dos estabelecimentos comerciais foi possível identificar Salmonella enterica transportando o Integron de classe 1, demonstrando a ubiquidade do mesmo. O gene invA foi identificado em 100% (59/59), sseD em 92,53% (54/59), lpfA em 86,51% (52/54) e spvR em 86,18% (49/59) dos sorovares de Salmonella enterica. Foram identificados seis perfis de virulência (A, B, C, D, E e F). Ao todo, 77,97 % dos isolados se agruparam no perfil A, caracterizado pela presença dos quatro genes de virulência simultaneamente. O conhecimento dos perfis de virulência dos isolados permite afirmar que os sorovares identificados no estado de Goiás são potencialmente virulentos e capazes de desencadear doença em sistemas de produção avícola e em humanos.
3

Deciphering regulatory mechanism influencing qepA efflux pump expression in Escherichia coli

Gockel, Jonas January 2020 (has links)
QepA is a plasmid-mediated efflux pump found in some strains of Escherichia coli, in which it significantly elevates the resistance against quinolones. The protein has similarities with 14-TMS major facilitator superfamily transporters and is situated in the inner membrane of the bacteria. It was acquired by horizontal gene transfer and integrated into a now inactivated class 1 integron, also harbouring several other antibiotic resistance genes such as rmtB and blaTEM-1. QepA alone is not sufficient to raise the resistance level over the clinical breakpoint and is in clinical isolates therefore associated with other quinolone antibiotic resistance genes or quinolone target point mutations. The mechanisms regulating qepA expression are not yet understood. Therefore, in this study the qepA gene was amplified from an E. coli clinical isolate and, together with its upstream promotor sequence, was inserted into the E. coli chromosome. It was shown that qepA gene expression can be induced by exposure to 0.5-fold MIC concentrations of ciprofloxacin, trimethoprim and other DNA damaging antimicrobials. The deletion of a LexA binding site situated after a PcW promotor, which was predicted to drive qepA expression, did not alter this induction behaviour. Nested deletions of up to 200 nts downstream sequence of the PcW promotor, led to the identification of a sequence region required for expression induction. This study showed that qepA expression is induced by environmental factors leading to DNA damage and further identified a previously unknown DNA sequence required for expression regulation.

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