Submitted by JAILA FERREIRA MELO null (jailaferreiramelo@yahoo.com.br) on 2016-01-11T23:05:53Z No. of bitstreams: 1 dissertação corrigida 2.pdf: 744284 bytes, checksum: 8607fad88a80aa948935c605abd7eb0a (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-01-12T11:23:01Z (GMT) No. of bitstreams: 1 melo_jf_jabo_int.pdf: 744284 bytes, checksum: 8607fad88a80aa948935c605abd7eb0a (MD5) / Made available in DSpace on 2016-01-12T11:23:01Z (GMT). No. of bitstreams: 1 melo_jf_jabo_int.pdf: 744284 bytes, checksum: 8607fad88a80aa948935c605abd7eb0a (MD5) Previous issue date: 2015-12-18 / A cultura da laranja no Brasil é afetada por várias doenças, como a gomose, causada por Phytophtora nicotianae Breda de Haan (synonymous whit P. parasítica Dast.), cujo controle é comumente realizado com aplicações de fungicidas e medidas de exclusão. Porém, devido aos custos financeiros e problemas ambientais ocasionados pelo uso intenso destas aplicações, faz-se necessário a busca por métodos alternativos de controle. Este trabalho teve por objetivo avaliar 50 isolados de Trichoderma spp. como antagonista de P. nicotianae, sendo que os isolados foram avaliados, através da produção de compostos antimicrobianos por meio destes microrganismos, além da realização de um bioensaio com plântulas de alfafa. No cultivo pareado observou-se que todos os isolados inibiram o crescimento micelial do fitopatógeno. Na produção de compostos antimicrobianos, 41 isolados produziram compostos voláteis utilizando dextrose como fonte de carbono. No entanto, em estudos posteriores, foi verificado que a utilização de sacarose ou maltose como fontes de carbono, aumentou a produção destes compostos. Sete isolados de Trichoderma produziram compostos termoestáveis e 14 produziram compostos antimicrobianos livres de células do antagônico. No bioensaio com plântulas de alfafa foi observado que quatro isolados de Trichoderma inibiram a formação de esporângios e de micélios do fitopatógeno. Diante dos resultados obtidos, concluiu-se que as avaliações in vitro com relação à produção de compostos antimicrobianos pelos isolados de Trichoderma e o bioensaio com plântulas de alfafa mostraram capacidade para selecionar isolados com potencial para o controle de P. nicotianae. Os isolados TB12, TB14, TB28 e TB 30 foram os que proporcionaram maior controle da doença. / Orange crops in the Brazil are affected by various diseases such as gummosis caused by Phytophtora nicotianae Breda de Haan (synonymous whit P. parasítica Dast.), which is controlled by chemical fungicides. However, the high costs and environmental problems caused by the intensive use of these fungicides have led to the search for alternative methods of control. The objective of this study was to evaluate the antagonistic activity of 50 Trichoderma spp. isolates against P. nicotianae by the production of antimicrobial compounds and an alfalfa seedling bioassay. The paired culture showed that all isolates tested inhibited the mycelial growth of the pathogen. In the production of antimicrobial compounds, 41 isolates produced volatile compounds using dextrose as carbon source; however, further assays showed that the use of sucrose or maltose as carbon source increases the production of these compounds. Seven isolates of Trichoderma spp. produced thermostable compounds and 14 isolates produced cell-free culture antimicrobial compounds of the antagonist. In the alfalfa seedling bioassay, four isolates of Trichoderma spp. inhibited the formation of sporangia and mycelia growth. The evaluation in vitro concerning to the antimicrobial compound production by the Trichoderma spp. isolates and the alfalfa seedling bioassay both were able to select biocontrol agents to control of P. nicotianae. The Trichoderma spp. isolates, TB12, TB14, TB28, and TB30 presented the best disease control.

Wastewater, recycled irrigation water, and agricultural runoff can contain high levels of pathogenic bacteria, which pose a threat to human and ecosystem health. The use of a bioreactor containing mycelial mats of filamentous fungi is a novel treatment technology that incorporates physical, biological, and biochemical processes to remove bacterial pathogens from influent water. Although a relatively new concept, fungal bioreactors have demonstrated the ability to dramatically reduce fecal coliform bacteria in water, but no studies have attempted to explicitly identify the bacterial pathogen removal mechanisms exhibited by the fungi. This study evaluated several different species of fungi for use in fungal bioreactor systems and aimed to identify the modes of action responsible for the removal of bacterial pathogens. The species evaluated were Daedaleopsis confragosa, Pleurotus eryngii, and Piptoporus betulinus. Experimental results showed that all species of fungi assessed were capable of removing E. coli in a synthetic water solution. Significant concentrations of hydrogen peroxide, an antiseptic, were produced by all species of fungi evaluated. The fungal bioreactors containing P. eryngii produced the highest concentrations of hydrogen peroxide, generating a maximum concentration of 30.5 mg/l or 0.896 mM. This maximum value exceeds reported minimum concentrations required to demonstrate bacteriostatic and bactericidal effects when continually applied, providing evidence that a major bacterial removal mode of action is the production of antimicrobial compounds. In addition to its promising application to improve water quality, fungal bioreactors are a low cost and passive treatment technology. The development a hyper-functional system could be a have a substantial impact on the use of recycled irrigation water and on the water/wastewater treatment industry, for both municipal and agricultural wastewater. / Master of Science

Thesis (M. Sc. (Microbiology)) -- University of Limpopo, 2022 / Dental diseases are among the most prevalent diseases worldwide. A recent epidemiological survey has shown that about 49 to 83% people are affected by dental caries. Carissa bispinosa (L.) Desf. ex Brenan is one of the medicinal plants used traditionally to treat dental diseases. This study aims to investigate the effectiveness of antimicrobial compounds from the leaf and stem extracts of C. bispinosa on oral pathogens. Nine solvents (n-hexane, chloroform, dichloromethane, ethyl acetate, acetone, ethanol, methanol, butanol and water) were used for the extraction of the leaf and stem powder of C. bispinosa. Biochemical tests were performed to determine the presence of phytochemical constituents and the phytochemical profile was generated through thin layer chromatography (TLC). TLC- 2, 2-diphenyl-1-picrylhydrazyl (TLC-DPPH) assay was used to determine the qualitative antioxidant activity while DPPH free radical scavenging and ferric reducing power assay were used for the quantification of antioxidant activity. The antimicrobial activity was tested on five pathogens (Staphylococcus aureus, Enterococcus faecalis, Streptococcus pyogenes, Candida albicans and Candida glabrata) qualitatively using the TLC-bioautography assay and quantitatively using the minimum inhibitory concentration (MIC) assay. Cytotoxicity was tested on the THP-1 cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The active compound was isolated through open column chromatography and preparative-TLC guided by bioassays. Structural elucidation was achieved from the analysis of spectral data generated by nuclear magnetic resonance (NMR) techniques. A variety of phytochemicals were detected on the leaf and stem extracts. The extracts had high antioxidant activity, especially those extracted with polar solvents. All the pathogens, except C. glabrata, demonstrated susceptibility to the extracts on the qualitative assay. For the leaf extracts, methanol extract had the lowest average MIC value (0.81 mg/ml) making it the most activity across the microorganisms, whereas hexane had the highest MIC value (1.63 mg/ml). C. albicans demonstrated higher susceptibility with an average of 0.73 mg/ml while C. glabrata displayed the least (2.8 mg/ml). Compared to the leaf extracts, lesser activity was observed for the stem extracts on bioautography and MIC. The percentage viability was decreasing as the concentration of the extract was increasing. However, the highest concentration resulted xxiv in more than 50% cell viability. The compound was isolated as a white powder (10.5 mg). It was identified based on its physical properties, spectroscopic data and comparing the data with scientific literature and was found to be β-Sitosterol, a member of plant steroids (Phytosterols). The study is the first to detect the presence of the antimicrobial compound (β-Sitosterol) and isolate it from the leaves of Carissa bispinosa. / Department of Science and Innovation-Council for Scientific and Industrial Research

Tesis por compendio / [ES] En la presente tesis doctoral se ha evaluado el uso de nuevos soportes celulósicos y silíceos como sistemas de filtración para la estabilización y conservación de alimentos líquidos con el fin de afrontar dos grandes retos de la industria de bebidas. Por un lado, evitar o minimizar los cambios en las propiedades nutricionales, estructurales y organolépticas de los alimentos, ocasionados por la pasteurización térmica tradicional, y ofrecer una alternativa al problema de la baja viabilidad debida a los altos costos de inversión/producción al aplicar nuevas tecnologías no térmicas. Por ello, esta tesis doctoral se centra en el desarrollo y evaluación de una nueva tecnología no térmica de conservación de alimentos líquidos basada en la filtración. Se han desarrollado sistemas de filtración a partir de soportes celulósicos y silíceos, sin funcionalizar o funcionalizados con compuestos antimicrobianos. En el primer capítulo se evaluó el uso de materiales de celulosa como soportes filtrantes para el tratamiento de alimentos líquidos. Como primera aproximación se desarrolló un material poroso nano-micro tubular a partir de la extracción y deslignificación del material celulósico presente en el corazón o raquis de la mazorca de maíz. El uso de este soporte resultó ser efectivo como material filtrante para el tratamiento de agua y zumo de naranja, en un sistema de flujo continuo, eliminando la carga microbiana. La aplicación de este soporte como sistema de filtración presenta diversas ventajas como su capacidad de retención microbiana, la reutilización de sub-productos del maíz y, por tanto, su respeto al medioambiente. Sin embargo, sería necesario optimizar el proceso de filtrado para evitar la frecuente obturación de sus poros que requirió varios ciclos de lavado durante el proceso, así como establecer un método de regeneración del material para incrementar su vida útil. Además, este sistema afectó al color del zumo filtrado, que no se mantuvo constante durante el proceso, lo que supone una importante desventaja que es necesaria abordar. Como segunda aproximación, se evaluó el potencial de la inmovilización de una molécula bioactiva sobre membranas de celulosa, para mejorar la capacidad de retención microbiana del material celulósico, así como permitir su reutilización. Los filtros de celulosa funcionalizados con poliaminas demostraron ser eficaces en la eliminación de patógenos en agua, debido a las cargas positivas generadas por los grupos amina inmovilizados en la superficie de las membranas, que atraen y retienen las bacterias cargadas negativamente. Dada la fácil preparación y procedimiento de uso de las membranas de celulosa funcionalizadas con poliaminas, éstas podrían ser consideradas una buena opción para el desarrollo de sistemas de tratamiento de aguas in situ, rápidos, de fácil manejo y de bajo coste. El segundo capítulo describe el desarrollo y aplicación de partículas de sílice funcionalizadas con compuestos de aceites esenciales, con el fin de diseñar coadyuvantes de filtración con actividad antimicrobiana. La filtración de diversas matrices alimentarias (agua, cerveza y zumo de manzana) a través de los soportes funcionalizados con los antimicrobianos naturales demostró ser eficaz en la reducción del recuento de la cepa patógena Escherichia coli, así como frente a la microflora endógena de la cerveza y el zumo (bacterias acidolácticas, aerobios mesófilos, psicrófilos, mohos y levaduras). La eficacia en el control microbiano se debe a la combinación de la adsorción física y la inactivación por contacto con los compuestos de aceites esenciales inmovilizados. Además, la evaluación de las propiedades físico-químicas y sensoriales de los alimentos líquidos demostró un efecto poco significativo, éste depende del tamaño de las partículas de sílice usadas y de la molécula bioactiva inmovilizada. Por lo tanto, el sistema de conservaci� / [CA] En la present tesi doctoral s'ha avaluat l'ús de nous suports cel·lulòsics i silicis com a sistemes de filtració per a l'estabilització i conservació d'aliments líquids, amb la finalitat d'afrontar dos grans reptes de la indústria de begudes. D'una banda, evitar o minimitzar els canvis en les propietats nutricionals, estructurals i organolèptiques dels aliments, ocasionats per la pasteurització tèrmica tradicional, i oferir una alternativa al problema de la baixa viabilitat deguda als alts costos d'inversió/producció en aplicar noves tecnologies no tèrmiques. Per això, aquesta tesi doctoral es centra en el desenvolupament i avaluació d'una nova tecnologia no tèrmica de conservació d'aliments líquids basada en la filtració. S'han desenvolupat sistemes de filtració a partir de suports cel·lulòsics i silicis, sense funcionalitzar o funcionalitzats amb compostos antimicrobians. En el primer capítol es va avaluar l'ús de materials de cel·lulosa com a suports filtrants per al tractament d'aliments líquids. Com a primera aproximació es va desenvolupar un material porós nano-micro tubular a partir de l'extracció i deslignificació del material cel·lulòsic present en el cor o raquis de la panolla de dacsa. L'ús d'aquest suport va resultar ser efectiu com a material filtrant per al tractament d'aigua i suc de taronja, en un sistema de flux continu, eliminant la càrrega microbiana. L'aplicació d'aquest suport com a sistema de filtració presenta diversos avantatges com la seua capacitat de retenció microbiana, la reutilització de subproductes de la dacsa i, per tant, el seu respecte al medi ambient. No obstant això, seria necessari optimitzar el procés de filtrat per a evitar la freqüent obturació dels seus porus que va requerir diversos cicles de rentada durant el procés, així com establir un mètode de regeneració del material per a incrementar la seua vida útil. A més, aquest sistema va afectar el color del suc filtrat, que no es va mantenir constant durant el procés, la qual cosa suposa un important desavantatge que és necessari abordar. Com a segona aproximació, es va avaluar el potencial de la immobilització d'una molècula bioactiva sobre membranes de cel·lulosa, per a millorar la capacitat de retenció microbiana del material cel·lulòsic, així com permetre la seua reutilització. Els filtres de cel·lulosa funcionalitzats amb poliamines van demostrar ser eficaces en l'eliminació de patògens en aigua, a causa de les càrregues positives generades pels grups amina immobilitzats en la superfície de les membranes, que atrauen i retenen els bacteris carregats negativament. Donada la fàcil preparació i procediment d'ús de les membranes de cel·lulosa funcionalitzades amb poliamines, aquestes podrien ser considerades una bona opció per al desenvolupament de sistemes de tractament d'aigües in situ, ràpids, de fàcil maneig i de baix cost. El segon capítol descriu el desenvolupament i aplicació de partícules de sílice funcionalitzades amb compostos d'olis essencials, amb la finalitat de dissenyar coadjuvants de filtració amb activitat antimicrobiana. La filtració de diverses matrius alimentàries (aigua, cervesa i suc de poma) a través dels suports funcionalitzats amb els antimicrobians naturals va demostrar ser eficaç en la reducció del recompte del cep patogen Escherichia coli, així com enfront de la microflora endògena de la cervesa i el suc (bacteris àcid làctics, aerobis mesòfils, psicròfils, floridures i llevats). L'eficàcia en el control microbià es deu a la combinació de l'adsorció física i la inactivació per contacte amb els compostos d'olis essencials immobilitzats. A més, l'avaluació de les propietats fisicoquímiques i sensorials dels aliments líquids estudiats va demostrar un efecte poc significatiu, aquest depèn de la grandària de les partícules de sílice usades i de la molècula bioactiva immobilitzada. Per tant, el sistema de conserv / [EN] In the present doctoral thesis the use of new cellulosic and silica supports as filtering systems for the stabilization and preservation of liquid foods has been evaluated to overcome two major challenges of the beverage industry. On the one hand, avoid or minimize the changes in the nutritional, structural and organoleptic properties of food caused by traditional thermal pasteurization, and offer an alternative to the problem of low viability due to high investment/production costs when applying new non-thermal technologies. Therefore, this doctoral thesis focuses on the development and evaluation of a new non-thermal technology for the preservation of liquid foods based on filtration. The filtering systems have been developed from cellulosic and silica supports, non-modified or functionalized with antimicrobial compounds. In the first chapter, the use of cellulose materials as filtering supports for the treatment of liquid foods was evaluated. As first approximation, a porous nano-micro tubular material was developed from the extraction and delignification of the cellulosic material present in the corn stalk. The use of this support was effective as filtering material for the treatment of water and orange juice, in a continuous flow system, eliminating the microbial load. The application of this support as filtering system has several advantages, such as its microbial retention capacity, the reuse of corn by-products and, therefore, its respect for the environment. However, it would be necessary to optimize the filtering process to avoid the frequent clogging of its pores that required several washing cycles during the process, as well as to establish a method of material regeneration to increase its life. In addition, this system affected the color of the filtered juice, which did not remain constant during the process, representing an important disadvantage that must be addressed. As a second approach, the potential of the immobilization of a bioactive molecule on cellulose membranes was evaluated to improve the microbial retention capacity of the cellulosic material, as well as to allow its reuse. The cellulose filters functionalized with polyamines proved to be effective in eliminating pathogens in water, due to the positive charges generated by the amine groups immobilized on the surface of the membranes, which attract and retain the negatively charged bacteria. Given the easy preparation and usage of the polyamines-functionalized cellulose membranes, these could be considered a good option for the development of fast, easy to use and low cost in situ water treatment systems. The second chapter describes the development and application of silica particles functionalized with essential oil components to design filtering aids with antimicrobial activity. The filtration of various food matrices (water, beer and apple juice) through the supports functionalized with natural antimicrobials proved to be effective in reducing the load of the pathogenic strain Escherichia coli, as well as reducing the endogenous microflora of beer and the juice (lactic acid bacteria, mesophilic, psychrophilic, mold and yeast). The removal capability is due to the combination of physical adsorption and contact inactivation with the essential oil compounds immobilized. In addition, the evaluation of the physicochemical and sensory properties of the liquid foods studied showed a not significant effect, it depends on the size of the silica particles used and the immobilized bioactive molecule. Therefore, the proposed preservation system has a high potential for cold beverage pasteurization processes. / N. Peña-Gomez would like to thank for financial support in the frame of her PhD project to Operational Programme of the European Social Fund (ESF) 2014-2020, the Agencia Estatal de Investigación, Generalitat Valenciana and FEDER-EU (Projects RTI2018-101599-B-C21 and AGL2015-70235-C2-1-R). The authors also thank the Electronic Microscopy & Microanalysis Laboratory at Patras University for support. / Peña Gomez, N. (2020). Development of polymeric and silica filtering materials functionalized with antimicrobial compounds for the elimination of microorganisms in liquid food [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/137041 / Compendio