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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.

The bacterial quality of effluent-irrigated crops : Public health implications

Vaz da Costa Vargas, S. M. January 1988 (has links)
No description available.

Escherichia coli in retail processed foods : a source of pathogenic strains for man

Pinegar, Arthur John January 1989 (has links)
No description available.

Incidence and importance of Bacillus species in raw milk and in the dairy environment

Beattie, Sally Heather January 1997 (has links)
No description available.

Investigation into the bacterial contamination in a spring water distribution system and the application of bioremediation as treatment technology

Behardien, Latiefa January 2008 (has links)
Spring water bottled and sold for human consumption can only be subjected to certain treatment processes such as separation from unstable constituents by decantation, filtration and aeration, ultraviolet irradiation and ozonation. A spring water distribution system in the Western Cape, South Africa was experiencing microbiological problems. The aim of the study was to investigate bacterial contamination in the spring water distribution system and the application of bioremediation as treatment technology. Sampling at various points in the spring water distribution bottling system started in February 2004 and continued until November 2004. The acceptable microbiological limits for bottled spring water clearly states that the total viable colony count should be < 100 organisms per ml of water. Analysis of samples by the heterotrophic plate count (HPC) technique indicated significantly (p < 0.05) high counts which did not conform to the microbiological limit. The heterotrophic plate counts recorded for weeks one, four, eight & 46 in the final bottled water (Site J) were 3.66 x 107 cfu/ml, 9.0 x 106cfu/ml, 2.35 x 107 cfu/ml and 5.00 x 104 cfu/ml, respectively. The total cell counts [Flow cytometry analyses (FCM)] recorded for week one, four, eight & 46 in the final bottled water (Site J) were 5.44 x 107 microorganisms/ml, 8.36 x 107 microorganisms/ml, 9.09 x 107 microorganisms/ml and 5.70 x 107 microorganisms/ml, respectively. The higher viable total cell counts(FCM) indicate that flow cytometry was able to detect cells in the water sample that enter a viable but not culturable state and that the heterotrophic plate count technique only allowed for the growth of the viable and culturable cells present in the water samples. This indicated that the HPC is not a clear indication of the actual microbial population in the water samples. It could be concluded that FCM technique was a more reliable technique for the enumeration of microbial populations in bottled water samples. Various organisms were identified by means of the Polymerase Chain Reaction (PCR) using 16S rRNA specific primers. Purified PCR amplicons were sequenced and Phylogenetic trees were constructed. Neighbour-joining phylogenetic tree analysis of the bacterial species present in the water samples was performed. The dominant bacterial isolates that were sequenced from the various water samples throughout weeks one, four, eight and 46 were Bacillus sp. and Enterobacteriaceae. The pathogenic species isolated throughout the sampling period included Escherichia sp., Pseudomonas sp., Shigella boydii, Bacillus and Staphylococcus sp. A laboratory-scale bioreactor was constructed and water samples were analysed over a period of two weeks. Water samples were analysed using FCM and Direct Acridine Orange Count (DAOC) in conjunction with epiflourescence microscopy (EM). The FCM counts ranged from 1.53 x 107 microorganisms/ml in the initial sample (Day 0) to 1.16 x 107 microorganisms/mℓ in the final sample (Day 13). The results indicated a 24% decrease in the microbial numbers however, it was still above the limit of < 100 organisms/ml as set out by the South African Standards of Bottled Water, (2003). The total cell counts obtained by the DAOC method ranged from 1.43 x 106 microorganisms/ml to 9.54 x 105 microorganism/ml on day 13 (final). The results indicated a 33% decrease in microbial numbers. The total cell counts analysed by flow cytometry fluctuated throughout the sampling period. The total cell counts obtained from the DAOC method were lower in all the water samples when compared to the total counts obtained by flow cytometric analyses. Even though the FCM counts fluctuated throughout the sampling period, results clearly show that the FCM method yielded more accurate data for total cell counts than the DAOC method. Due to external environmental conditions such as changes in the weather conditions the results fluctuated and the final results clearly indicated that further studies are required to optimise the bioreactor system for its application in the spring water industry.

Bacterial levels in Saskatchewan retail ground beef

2013 December 1900 (has links)
This thesis describes the results of three studies that used different measures of bacterial numbers in retail ground beef (n=309) collected across different locations in Saskatchewan within a one-year period (May 2011 – May 2012). The measurements were compared among three sample categories: 1 - ground beef displaying government inspection information on the label legend (n=126), 2 - originating from facilities licensed by local health regions and thus not subjected to government inspection (n=80), or 3 - processed and repackaged at the retail level thus carrying no government inspection information on the label (n=103). The first study reports baseline levels of bacteria in Saskatchewan retail ground beef as measured by traditional (total aerobic plate count (TAPC) and total E. coli plate count (TEPC)) and culture-independent methods (estimate of total bacterial load (TBL) by real-time quantitative polymerase chain reaction). After accounting for season and whether the samples were fresh or frozen at purchase, the lowest TAPC (log10 4.9 culture forming units per gram (cfu/g); 95% CI log10 4.7 to log10 5.1 cfu/g), TEPC (log10 0.58 cfu/g; 95% CI log10 0.39 to log10 0.77 cfu/g), and TBL in frozen ground beef (log10 4.5 target copies per gram (tc/g); 95% CI log10 4.0 to log10 4.9 tc/g) were observed in samples originating from federally regulated or provincially licensed facilities. In the second study, presence of known Enterobacteriaceae virulence factors (stx1, stx2, and eae) was detected by polymerase chain reaction (PCR) and compared between samples originating from three different regulatory and inspection environments as well as collected during different seasons of the year, and purchased fresh or frozen. One hundred and twelve out of all tested samples (n=308) were positive for the presence of at least one virulence marker with stx1 identified in 107 samples, stx2 - in 8, and eae - in 26. No significant associations were found between the virulence markers presence and sample category, state or season of purchase. The third study investigates the presence and diversity of Campylobacter spp. organisms in the same pool of 309 retail beef samples as detected by molecular methods. Fifty samples (16.2%) tested positive for Campylobacter genus-specific DNA in conventional PCR and 49 samples (15.9%) tested positive for at least one Campylobacter species DNA presence in real-time qPCR, but the crude agreement between the two methods was less than 50%. C. coli DNA presence was observed in 14 samples (4.5%), C. curvus – in 11 (3.6%), C. fetus – in 6 (1.9%), C. hyointestinalis – in 24 (7.8%), C. jejuni – in 12 (3.9%), C. rectus – in 6 (1.9%), and C. upsaliensis – in 9 (2.9%). There was no difference in the frequency of Campylobacter identified among the three sample categories, fresh and frozen, or samples purchased during the cold or warm season. These studies provide data on prevalence of bacteria in retail ground beef offered for sale in Saskatchewan and compare differences between samples presented to the consumer as originating from federally regulated or provincially licensed facilities, locally licensed facilities, or repackaged and processed directly at a retail outlet. The information on baseline levels of bacteria in retail ground beef and the comparisons among different categories can be used in prioritising food safety improvement efforts in Saskatchewan.

Qualidade microbiológica de águas minerais em garrafas individuais comercializadas em Araraquara

Dias, Maria Fernanda Falcone [UNESP] 22 November 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-22Bitstream added on 2014-06-13T20:56:36Z : No. of bitstreams: 1 dias_mff_me_arafcf.pdf: 401309 bytes, checksum: 3615bf97747cd9d854c75ca926044788 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Com a dúvida sobre a qualidade da água de abastecimento público, o cidadão passou a utilizar a água mineral com maior intensidade. Para atender a esta demanda as indústrias aumentaram a produção, novas empresas surgiram e também os falsários. Assim, é necessário conhecer-se a qualidade esperada e paga pelo consumidor nesse produto, realmente existe. O objetivo desta pesquisa foi avaliar aspectos de qualidade microbiológica em amostras de água mineral natural, não carbonatada, em garrafas individuais de 330mL a 600mL, das diversas marcas comercializadas em supermercados na cidade de Araraquara-SP. Foram utilizadas sessenta e nove amostras provenientes de dezessete marcas. As amostras foram adquiridas aleatoriamente, em épocas e estabelecimentos diferentes para que fossem originadas de lotes diversos. Para análise de coliformes totais e coliformes fecais/E. coli utilizou-se a técnica de substratos cromogênicos; para enterococos e Pseudomonas aeruginosa foram utilizadas as técnicas de tubos múltiplos específicas; para contagem de bactérias heterotróficas, foi utilizada a técnica de cultivo em profundidade. Todas as amostras de todas as marcas (100%) apresentaram ausência de coliformes fecais/E.coli, duas amostras (2,9%) de uma marca (5,9%) apresentaram contaminação por coliformes totais, duas amostras (2,9%), de duas marcas (11,8%) apresentaram contaminação por enterococos, três amostras (4,3%) de duas marcas (11,8%) apresentaram Pseudomonas aeruginosa e quarenta amostras (58%) de doze marcas (70,6%) apresentaram contagens acima de 500 UFC/mL para bactérias heterotróficas. Verificou-se que, das sessenta e nove amostras analisadas (100%) apenas seis (8,7%) apresentaram-se contaminadas com um ou mais dos indicadores especificados pela legislação brasileira para águas minerais. Entretanto, considerando os padrões para água mineral e o padrão... / With the doubt on the water quality in public supplying, the citizen started to use the mineral water with larger intensity. For attend this demand the factory had increased the production, new companies had appeared and also the falsifiers. Thus, it’s necessary to know if the quality waited and paid for the consumer in this product, really exists. The objective of the research was to evaluate aspects of microbiological quality in natural mineral water samples, not carbonated, in individual bottles of 330mL to 600mL, of the diverse marks commercialized in supermarkets in the city of Araraquara-SP. Sixty nine samples proceeding from seventeen marks had been used. The samples had been acquired aleatory, at different times and establishments for that they were originated from diverse lots. For analysis of fecal coliform/E. coli and total used it cromogenic substrate technique; for enterococcus and for Pseudomonas aeruginosa was used the technique of multiple tube specific; for counting of heterotrophic bacteria, was used the technique of culture in depth. All the samples of all the marks (100%) had presented absence for fecal coliform/E.coli., two samples (2.9%) of one mark (5.9%) had presented contamination for total coliform, two samples (2.9%), of two marks (11.8%) had presented contamination for enterococcus, three samples (4.3%) of two marks (11.8%) had presented Pseudomonas aeruginosa, and forty samples (58%) of twelve marks (70.6%) had presented counting above of 500 CFU/mL for heterotrophic bacteria. It was verified that, of the sixty nine analyzed samples (100%), only six (8.7%) had been presented contaminated with one or more than the pointers specified for the Brazilian legislation for mineral waters used in this research. However, considering the standards for mineral water and the standard for heterotrophic bacteria established by the legislation for water of human consumption...(Complete abstract click electronic access below)

Valgomojo rūgštinio kazeino bendras bakterinis užterštumas / General bacterial contamination of edible acid casein

Šinkūnienė, Neringa 19 April 2005 (has links)
Casein – the main albumen constituent of milk. Food casein is used in the production of caseinat. Caseinats are used in the production of food concentrates, medicines, and cheese products. In addition, they may be used as casein glue. Goals of thesis. To determinate total bacterial contamination of acid casein edible, isolate and identify pathological microorganisms. 1. To determine the general bacterial contamination of edible acid casein samples. 2. To determine the influence of thermophylic bacteria on the general bacterial contamination. 3. To determine the general bacterial contamination of repeatedly researched edible acid casein samples and the presumable quantity of coliformic germs. 4. To define and identify the patological microorganisms out of edible acid casein samples. 5. To determine the chemical composition of edible acid casein samples. Results. Micro flora of crude milk constitutes certain part of micro flora, found in powdered milk. However, the increased level of general contamination and coliform germs shows the signs of secondary contamination. The enlarged bacteriological contamination, which exceeded the preset limit of 3.0x104 CFU/g, was identified in 3 per cent of analyzed acid casein edible samples. This was caused by impurity of crude milk. During the acid casein edible casein production process, the temperature of pasteurization was reached twice and in addition to that, comparatively low pH was maintained. These conditions are not hospitable for... [to full text]

Food Safety Know-how

Misner, Scottie, Whitmer, Evelyn 12 1900 (has links)
1p. / Most of the "bad food" reported illnesses are due to bacterial contamination. Nearly all of these cases can be linked to improper food handling, both in our homes and in restaurants. This article briefly discusses the causes of food contamination and how to handle food safely.

Spatial and temporal analysis of the distribution of bacterial contamination in nearshore areas of Southern Vancouver Island

Xu, Kaifeng 19 September 2018 (has links)
This research conducts a spatial and temporal analysis of the distribution of fecal coliform throughout the Capital Regional District (CRD) of southern Vancouver Island. The research is based on 17 years of historical data of stormwater samplings from 1995 to 2011 in the nearshore region. ArcGIS is used to map the fecal coliform data collected within and adjacent to nearshore areas to identify peaks above a regulated threshold. Heavily polluted areas are in Victoria downtown, Esquimalt and the southeastern shore of Oak Bay. Land-use data and drainage patterns are used to determine relationships between fecal coliform levels and land-use by considering relevant, temporally dependent factors. Temperature is positively correlated with FC level and precipitation is negatively correlated. The residential land use is identified as the main source of bacterial contamination. This analysis leads to a regression model that indicates two peaks (July and October) of FC level occur in a 12-month period and positively related to minimum temperature and cloud cover ratio. / Graduate

Avaliação in vitro da capacidade de vedamento bacteriano da interface implante e componente protético em sistema cone Morse em função de alterações estruturais e uso de selantes industriais / In vitro evaluation of the sealing ability of bacterial interface implant and prosthetic component in Morse taper system due to structural changes and the use of industrial sealants

Antonio da Silva Ramos Neto 13 November 2013 (has links)
O objetivo deste estudo foi comparar, in vitro, os sistemas de implante cone Morse, frente ao vedamento contra a penetração bacteriana entre o implante e o componente protético, em função de alterações estruturais e uso de selantes industriais. Foram utilizados 126 implantes Titamax CM EX distribuídos em três tipos de componentes protéticos: Munhão Universal CM, Munhão Universal CM com Parafuso Passante e Munhão Universal CM Exact, todos da empresa Neodent (Curitiba, Paraná, Brasil). Estes implantes foram divididos em 3 grupos de 42 implantes componentes protéticos, sendo os grupos devidamente denominados: Grupo 1 (G1) - Controle, Grupo 2 (G2) - Jateamento e Grupo 3 (G3) - Adesivo. Estes implantes, devidamente distribuídos entre os componentes protéticos e seus grupos, foram avaliados quanto à contaminação bacteriana em um período de 28 dias após o término da experimentação inicial em que foi realizado o efeito de ciclagem sobre as amostras (sem e com carga). Os implantes foram perfurados em sua porção apical com uma fresa de 1mm de diâmetro, até o encontro de sua câmara interna. Foram instalados os componentes protéticos de titânio em cada grupo com torque recomendado pelo fabricante (32 e 15 N.cm). Antes os componentes dos grupos G2 e G3 passaram por alterações estruturais (jateamento e adesivo Dermabond® respectivamente). As peças foram anexadas a tampas de tubo de ensaio, com a porção do componente voltada para o interior do tubo. Os tubos de ensaio foram preenchidos com meio de cultura líquido LB, utilizando-se seringa estéril. Todos os conjuntos receberam esterilização por radiação Gama (Embrarad, Campinas, Brasil). Após a confirmação da efetividade da esterilização por meio de amostras controle, os orifícios apicais foram cuidadosamente desobstruídos e inoculados com cultura de E. coli. O controle de turvamento das amostras foi realizado diariamente, os resultados apontaram que três das amostras do G1, sete do G2 e duas do G3, que não foram submetidas a ciclagem, sofreram contaminação num período de até 28 dias, e que três amostras do G1, dez do G2 e nenhuma do G3, quando submetidas ao efeito da ciclagem, foram contaminaram. Todos os grupos apresentaram infiltração bacteriana, independentemente do componente protético e da ciclagem. Ficou evidenciado que o grupo jateamento apresentou os piores resultados e que o adesivo apenas reduziu, mas não impediu a infiltração bacteriana para o interior dos implantes cone Morse. / The aim of this study was to compare, in vitro, Morse taper implant systems sealing against bacterial penetration between implant and prosthetic component after modifying the abutment structure or using industrial strength sealants. 126 Titamax CM EX implants and three different types of prosthetic components were used: Universal Post CM, CM Universal Post with passing screw and Universal Post CM Exact (Neodent implants, Curitiba, Parana, Brazil). These samples were divided into three groups: Group 1 Control group (G1); Group 2 Sandblasting (G2); and Group 3 Adhesive (G3). The implant / prosthetic component bacterial leakage from each group was evaluated after 28 days with or without cyclic loading. A hole at the apical portion of the implant was done with a 1 mm bur to access the implant internal threads. The abutments were inserted and torqued according to the manufacturer recommendation (15 or 32 N.cm). G2 abutments were sandblasted before insertion. G3 abutments were sealed with Dermabond® adhesive. The samples were sterilized by Gamma irradiation (Embrarad, Campinas, Brazil) and attached to the test tube lid and placed in the test tube filled with bacterial growth media (LB). Control samples from each group were used to assess bacterial contamination before starting the experiment. The access holes at the apical part of the implants were accessed and an E. coli culture was inoculated inside the implant internal threads and then sealed again. Changes in the media color (turbidity), indicative of bacterial leakage from inside the implant to the media were evaluated daily. Three samples from G1, seven from G2 and two from G3 without cyclic loading showed bacterial leakage after 28 days. Three samples from G1, ten from G2 and none of the samples from G3 showed bacterial leakage in the cyclic loading condition. All groups demonstrated bacterial leakage disregard of the type of abutment and loading conditions. It was demonstrated that G2 (sandblasted surface) had the worst results. Use of industrial sealant reduced but did not completely prevented bacterial leakage in Morse taper implants.

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