The contact zone between a root and the surrounding soil mediates processes such as nutrient and water uptake and the interaction with microorganisms. Despite the importance of the contact zone, there is a lack of understanding of the specific characteristics and their relevance to plant performance and microbial colonization. The objective of this thesis was, therefore, to investigate the effect of the extent and characteristics of this root-soil contact zone on plant performance and microbial abundance, and community structure. In particular, I addressed the following research questions: I.) How do specific root traits impact the establishment of a contact zone and how do variations in the root-soil contact zone influence corresponding plant and microbial parameters?, II.) How do root-soil contact zone conditions furthermore modulate these responses? and III.) How do root-soil contact zone conditions modulate these responses in the field? In order to answer these questions, I conducted a literature review, two microcosms, and one field experiment. To modify the root-soil contact zone, I grew maize plants in treatments with artificial pores (abiogenic pores), with pores incubated with earthworms (biogenic pores), and, as a control, without additional pores. To analyze the microbial abundance and community diversity and composition, qPCR, fluorescence microscopy, and amplicon sequencing were used. Plant performance was assessed by endoscopy and measurements of plant height and weight and shoot nutrient contents. <br /> My results confirmed that the root-soil contact significantly influenced the occurrence of microorganisms on the root surface, as well as the diversity and composition of the bacterial community in the rhizosphere. The root-soil contact was especially important for nitrogen cycling microorganisms in the rhizosphere, as nitrifying bacteria were less abundant when the root established only partial soil contact. However, the level of root-soil contact had no effects on early plant performance in the microcosm experiments (research question I). When the contact zone between root and soil was enriched in nutrients, due to soil faunal activity in pores, the abundance of microorganisms at the pore wall as well as in the corresponding rhizosphere was increased, and microbial community composition was influenced (Research question II). The same trends can be seen in the field. Moreover, in the field experiment, which also covered later growth stages, reduced root-soil contact due to the presence of abiogenic pores resulted in growth deficits compared with the presence of biogenic pores and the absence of soil pores (Research question III). <br /> In summary, these findings underline the importance of root-soil contact and contact zone characteristics for rhizosphere processes and plant performance. Agricultural management should, therefore, aim to minimize cracks in the soil to guarantee root-soil contact and to improve plant performance by enhancing biological activity in pores.

Successful colonization of plants by endophytes is the basic requirement for plant-microbe interactions. Thus, the study of plant colonization routes and niches has always been a central aspect in research on plant-microbe interaction. Endophytic microorganisms can be detected by several methods based on microscopy, thus allowing to investigate their behavior, their niches, and how they colonize their hosts. Different techniques can be applied, depending on the study objectives, to single strains or to more complex plant-microbe systems involving full or synthetic microbiomes. Furthermore, the use of microscopy-based tools allows us to track endophytes in plant tissues and to determine how they interact with each other and with their host plants, as well as how they are associated with various plant organs under different plant growth and environmental conditions either from natural or artificial environments. This chapter describes the step-by-step protocol of distinct microscopy-based methods that may be used to visualize and track endophytic microorganisms within plant tissues.

Interbacterial competition assays have become an essential tool for understanding the interactions between bacteria and their ability to outcompete one another in natural environments. This is especially relevant when studying the type VI secretion system (T6SS), a contact-dependent bacterial weapon that can be used to kill or inhibit the growth of other competing bacteria. Some beneficial environmental microorganisms such as Pseudomonas putida rely on the T6SS as their primary biocontrol mechanism to eliminate resilient plant pathogens. Competition assays are an essential methodology in this field that allows us to understand the efficacy of this bacterial nanoweapon. This chapter outlines the methodology for conducting in vitro and in planta competition assays between P. putida, a well-known biocontrol agent, and phytopathogenic bacterial species of economic and scientific interest.

Mestrado em Engenharia Alimentar / Instituto Superior de Agronomia, Universidade de Lisboa | Milk, while being a very nutritive liquid, is also extremely perishable. In addition, if not properly preserved, milk can endanger consumer’s health due to the potential growth of pathogenic microorganisms that might be present. Heat is the most common method used by the dairy industry for microbial inactivation and milk pasteurization. However, thermal treatments have negative effects on milk nutrients and structure, which are important for human nutrition and to produce other dairy products. Therefore, non-thermal technologies are being developed and studied for the inactivation of microorganisms. Ultrasound utilizes soundwaves that are above the hearing range for humans. When acoustic waves pass through a liquid, food cavitation occurs, with lethal effects on microorganisms. Ultrasound can be combined with heat (thermosonication, TS) for more efficient microbial inactivation. The main objective of this study was to evaluate the efficacy of thermosonication treatments for Staphylococcus aureus pathogen inactivation in whole milk. Thermal inactivation alone was also assessed. The thermal and TS inactivation kinetics were modeled, and thermal resistance parameters were determined. TS treatments using 10 W/mL and isothermal temperatures (58 ºC, 63 ºC, and 66 ºC) were carried out. Exclusively thermal inactivation was investigated for 58 ºC, 63 ºC, 66 ºC, and 72 ºC. Thermosonication demonstrated a significant advantage over conventional thermal inactivation for all tested temperatures. Ultrasound at 58 ºC was much more efficient for S. aureus inactivation, reducing the D-value from 27.93 ± 1.73 to 1.99 ± 0.07 minutes. Reductions in the D-values of much lower magnitude were observed at higher temperatures: at 63 ºC, the D-value decreased from 2.12 ± 0.15 to 1.20 ± 0.07 minutes, and at 66 ºC, it dropped from 1.02 ± 0.06 to 0.14 ± 0.02 minutes. Ultrasound is a promising technology to speed up microbial inactivation and reduce temperatures or times required for milk pasteurization. | O leite é um alimento rico em nutrientes, extremamente perecível. A pasteurização do leite cru evita o crescimento de microrganismos de alteração e patogénicos, sendo o calor o método convencional mais utilizado na indústria dos lacticínios para a sua conservação e segurança. Os tratamentos térmicos afetam negativamente os nutrientes e a estrutura do leite. Neste contexto, é pertinente investigar a aplicação de tecnologias não térmicas de pasteurização. Os ultrassons utilizam ondas sonoras acima do alcance auditivo do ser humano. As ondas acústicas quando atravessam um alimento líquido geram a cavitação, que provoca danos letais nos microrganismos. Os ultrassons podem ser combinados com calor (TS, termossonicação) para uma inativação microbiana mais eficiente. O principal objetivo deste trabalho foi avaliar a eficácia da TS na inativação do microrganismo patogénico Staphylococcus aureus no leite. A inativação exclusivamente térmica foi também avaliada. As cinéticas de inativação por TS e inativação térmica foram modeladas e os parâmetros de resistência térmica foram determinados. Os tratamentos TS, com uma densidade de potência acústica de 10 W/mL, foram combinados com temperaturas de 58 ºC, 63 ºC e 66 ºC, enquanto a inativação exclusivamente térmica foi investigada para 58 ºC, 63 ºC, 66 ºC e 72 ºC. A TS demonstrou uma vantagem significativa sobre a inativação térmica convencional para todas as temperaturas testadas. Ultrassons a 58 ºC foi mais eficiente na inativação de S. aureus, reduzindo o valor D de 27,93 ± 1,73 para 1,99 ± 0,07 minutos. A temperaturas mais elevadas foram registadas reduções no valor D de menor magnitude: de 2,12 ± 0,15 para 1,20 ± 0,07 minutos (a 63 ºC), e de 1,02 ± 0,06 para 0,14 ± 0,02 minutos (a 66 ºC). Os resultados demonstram que os ultrassons são uma tecnologia promissora para acelerar a inativação de microrganismos e reduzir temperaturas e tempos da pasteurização. | N/A

Verheecke-Vaessen, Carol - Associate Supervisor Fontana, Angelique - Associate Supervisor Strub, Caroline - Associate Supervisor | This doctoral research delves into the innovative domain of biocontrol strategies targeting mycotoxigenic fungi in the context of climate change. Focusing on Ivorian coffee, a vital economic and agricultural commodity, the study explores the potential of indigenous lactic acid bacteria (LAB) and yeasts as biocontrol agents. Mycotoxins, toxic secondary metabolites produced by fungi, pose significant health risks and economic losses. As climate change amplifies the proliferation of mycotoxigenic fungi, the demand for sustainable and eco-friendly interventions intensifies. The research encompasses comprehensive isolation, identification, and characterization of LAB and yeasts from Ivorian coffee, evaluating their antagonistic properties against mycotoxigenic fungi. Furthermore, the study elucidates the mechanisms underlying the biocontrol activity, shedding light on how these microorganisms mitigate mycotoxin contamination. This research is pivotal in the pursuit of climate-resilient strategies for mycotoxin management, contributing to both food safety and agricultural sustainability. | PhD in Environment and Agrifood

Digital | Introducción: Las enfermedades infecciosas son una amenaza constante para la salud humana, agravada por el fenómeno de resistencia microbiana a los antibióticos de uso clínico. Esta situación ha impulsado la búsqueda de nuevos agentes antimicrobianos que puedan ser alternativos o complementarios a los tratamientos convencionales. Recientemente, nanomateriales como los puntos cuánticos de carbono (QDs) han sido propuestos en el tratamiento de enfermedades infecciosas ya que permiten la obtención de imágenes, uso como biomarcadores, detección e inhibición microbiana (bactericida) por sus propiedades ópticas, sus superficies químicas susceptibles a modificaciones y gran biocompatibilidad. Estos materiales pueden obtenerse de fuentes naturales de carbono como la biomasa residual de la actividad agroindustrial, como por ejemplo la cadena productiva de la sacha inchi (Plukenetia volubilis L.), contribuyendo así a las distintas estrategias de manejo integral de residuos. Sacha inchi es una especie oleaginosa de interés económico en nuestro país cuya semilla rinde un aceite nutritivo de tipo exportación. Del proceso de beneficio de la planta, se generan como residuos las cápsulas del fruto y las testas de la semilla, cuya biomasa representa más del 30% en masa del fruto y constituye un material biológico aprovechable para la generación de materiales funcionales como los QDs. Objetivos: Obtener dos muestras de puntos cuánticos de carbono a partir de las cápsulas y testas del fruto de sacha inchi (Plukenetia volubilis L.) y determinar su actividad antimicrobiana contra microorganismos de interés clínico como E. coli y S. aureus. Materiales y Métodos: Las muestras de puntos cuánticos (QDs) a partir de las cápsulas y testas de sacha inchi, se sintetizaron en un reactor hidrotermal a una temperatura de 180 °C y una presión de 40 bar durante 2 h. Posteriormente, se realizó la caracterización de los nanomateriales mediante espectroscopía infrarroja por Transformada de Fourier (FTIR) y Ultravioleta-visible (UV-vis) y se evaluó su actividad antimicrobiana contra microorganismos de interés clínico como E. coli y S. aureus mediante el método de microplaca estipulado en el Instituto de Normas Clínicas y de Laboratorio (CLSI). Resultados y Discusión: Se obtuvieron dos soluciones de QDs a partir de las cápsulas (QDs-C) y de las testas (QDs-T) del fruto de sacha inchi, ambas con emisión de fluorescencia de color azul. La caracterización química de los nanomateriales por UV-vis presentó bandas de absorción similares centradas en 350 y 340 nm para QDs-T y QDs-C, que denotan la presencia de compuestos con dobles enlaces y la presencia de heteroátomos. El espectro FTIR de los QDs mostró la presencia de grupos hidroxilo (-OH) propios de grupos ácidos(-COOH) y alcoholes (R-OH) o grupos amino (R-NH2), enlaces C-H y enlaces C=O. Para la actividad antimicrobiana, QDs-C y QDs-T presentaron una MIC de 1.25 mg/mL contra S. aureus. QDs-C a una concentración de 1.25 mg/mL inhibió el crecimiento de E. coli observándose valores de 0,4 en la absorbancia durante las primeras 20 horas, QDs-T no inhibieron a E. coli en ninguna de las concentraciones evaluadas y gentamicina presentó una MIC de 1.93x10-3 y 9.68x10-3 mg/mL para E. coli y S. aureus respectivamente. Conclusiones: en este trabajo de grado se obtuvieron puntos cuánticos a partir del tratamiento hidrotermal de la biomasa residual de las cápsulas (QDs-C) y testas (QDs-T) del fruto de sacha inchi, y se evaluó su potencial como agentes antimicrobianos contra microorganismos de interés clínico como S. aureus. y E. coli. De las dos soluciones de puntos cuánticos obtenidas, QDs-C y QDs-T presentaron una MIC de 1.25 mg/mL contra S. aureus. y solamente QDs-C inhibió el crecimiento de E. coli a una concentración de 1.25 mg/mL. Estos resultados permiten evidenciar el potencial de estos nanomateriales como posibles agentes antimicrobianos alternativos o complementarios a los agentes antimicrobianos convencionales. | Introduction: Infectious diseases are a constant threat to human health, aggravated by the phenomenon of microbial resistance to antibiotics in clinical use. This situation has prompted the search for new antimicrobial agents that can be alternative or complementary to conventional treatments. Recently, nanomaterials such as carbon quantum dots (QDs) have been proposed in the treatment of infectious diseases as they allow imaging, detection and microbial inactivation due to their optical properties, chemical surfaces susceptible to modification and high biocompatibility. These materials can be obtained from natural carbon sources such as residual biomass from agricultural activities. Objectives: To obtain two carbon quantum dot samples from sacha inchi (Plukenetia volubilis L.) fruit capsules and testes and to determine their antimicrobial activity against microorganisms of clinical interest such as E. coli and S. aureus. Objectives: To obtain two carbon quantum dot samples from the capsules and testes of the sacha inchi fruit (Plukenetia volubilis L.) and to determine their antimicrobial activity against microorganisms of clinical interest such as E. coli and S. aureus. Materials and Methods: In the present work we present the obtaining of two samples of quantum dots (QDs) from the capsules (QDs-C) and testas (QDs-T) of sacha inchi. The QDs were synthesized by means of a hydrothermal reactor at a temperature of 180 °C and a pressure of 40 bar during 2 h. At the end of the process, the functional groups were characterized by Fourier Transform Infrared Spectroscopy (FTIR), the Ultraviolet-visible (UV-vis) spectra were determined and their antimicrobial activity against microorganisms of clinical interest such as E. coli and S. aureus was evaluated. Results and Discussion: The obtained QDs exhibited luminescent properties with blue fluorescence emission. The chemical characterization of the nanomaterials by UV-vis presented similar absorption bands centered at 350 and 340 nm for QDs-T and QDs-C, denoting the presence of compounds with double bonds and the presence of heteroatoms. The FTIR spectra of the QDs showed the presence of hydroxyl groups (-OH) typical of acidic groups(-COOH) and alcohols (R-OH) or amino groups (R-NH2), C-H bonds and C=O bonds. For antimicrobial activity, QDs-C and QDs-T presented a MIC of 1.25 mg/mL against S. aureus. QDs-C at a concentration of 1.25 mg/mL inhibited the growth of E. coli with absorbance values of 0.4 during the first 20 hours, QDs-T did not inhibit E. coli at any of the concentrations evaluated and gentamicin presented a MIC of 1.93x10-3 and 9.68x10-3 mg/mL for E. coli and S. aureus, respectively. Conclusions: Quantum dots were obtained from the residual biomass of sacha inchi fruit capsules and testes. UV-vis and FTIR spectra revealed the presence of hydrophilic groups (-OH, -COOH R-NH2). Likewise, QDs-C and QDs-T exhibited antimicrobial inhibition against S. aureus, but not against E. coli. | Pregrado | Microbiólogo Industrial

Os produtos de pastelaria são apreciados globalmente. Desta forma, é importante estudar as características sensoriais e físico-químicas dos mesmos de modo a alcançar as exigências e preferências por parte do consumidor. Os ingredientes utilizados neste tipo de iguarias podem apresentar perigos de origem física, química e ainda, perigos de origem biológica que são os principais responsáveis por doenças de origem alimentar, levantando questões a nível da segurança alimentar dos produtos. O presente trabalho teve como objetivo a redução do teor de margarina utilizada no produto de pastelaria salgada Covilhete, através de vários estudos nutricionais, físicoquímicos, microbiológicos e sensoriais. Com este propósito, numa primeira fase do trabalho foram recolhidos 54 covilhetes (6 lotes x 3 tempos x 3 amostras). As amostras foram sujeitas a análises microbiológicas. Na segunda fase do trabalho, foram recolhidos 24 covilhetes (3 lotes x 2 amostras x 4 condições) após cozimento e, posteriormente foram determinados parâmetros físicoquímicos, nutricionais e microbiológicos em amostras de covilhete com margarinas diferentes e com uma redução de 20% de cada uma delas na sua formulação. Para além disso, foi também avaliado o perfil de ácidos gordos onde foi determinado o tempo de retenção dos ácidos gordos presentes e, os respetivos ácidos gordos. Por último, foi realizada uma análise sensorial com 97 provadores em que foram avaliados 4 tipos de covilhetes. Entre eles, covilhete tradicional, covilhete com uma redução de 20% do seu teor em gordura e um covilhete em que foi utilizada uma margarina diferente, que na sua constituição inclui gordura de palma RSPO-MB e um outro que contém a presença desta última margarina, mas com uma redução de 20%. De um modo geral, ao longo do processamento do covilhete verifica-se uma redução na presença de Bactérias do ácido lático (BAL), microrganismos mesófilos e E. coli ao longo do tempo e ausência de Staphylococcus aureus e Listeria monocytogenes em todas as fases do processamento do covilhete, revelando uma boa higienização dos utensílios e mãos. Em termos nutricionais e físico-químicos, o covilhete com margarina 100% vegetal apresenta um maior teor em água e menor teor em humidade e pH comparativamente ao covilhete tradicional, revelando um maior risco microbiano. Enquanto, o covilhete tradicional com redução de 20% de gordura é aquele que em termos de sal apresenta menores teores em relação às restantes amostras, mas que, apresenta um teor de proteína mais elevado. Na determinação do perfil de ácidos gordos no covilhete tradicional foi detetada presença de ácidos gordos esteárico e oleico enquanto, no covilhete com a mesma margarina, mas com a redução de 20% além desses apresenta também o ácido gordo palmítico. Por outro lado, em amostras cuja margarina introduzida inclui gordura de palma, predomina a existência de ácidos gordos esteárico e oleico. Relativamente à análise sensorial das quatro formulações, os provadores apresentaram preferência pelo covilhete tradicional com um menor teor em gordura, destacando-se pelo seu aspeto estaladiço, amanteigado, amarelo e um menor teor em sal relativamente ao sabor. | Pastry products are appreciated globally. It is therefore important to study their sensory and physical-chemical characteristics in order to meet consumer demands and preferences. The ingredients used in this type of delicacy can present physical and chemical hazards, as well as biological hazards, which are the main causes of food-borne illnesses, raising questions about the food safety of products. The aim of this study was to reduce the margarine content used in the savory pastry product Covilhete through various nutritional, physical-chemical, microbiological and sensory studies. To this end, 54 covilhetes (6 batches x 3 times x 3 samples) were collected in the first phase of the work. The samples were subjected to microbiological analyses. In the second phase of the work, 24 covilhetes (3 batches x 2 samples x 4 conditions) were collected after cooking and then physico-chemical, nutritional and microbiological parameters were determined in samples of covilhete with different margarines and with a 20% reduction of each of them in their formulation. In addition, the fatty acid profile was also evaluated, where the retention time of the fatty acids present and the respective fatty acids were determined. Finally, a sensory analysis was carried out with 97 tasters in which 4 types of covilhetes were evaluated. These included a traditional covilhette, a covilhette with a 20 per cent reduction in fat content, a covilhette in which a different margarine was used, including RSPO-MB palm fat, and another with the latter margarine, but with a 20 per cent reduction. In general, there was a reduction in the presence of lactic acid bacteria (LAB), mesophilic microorganisms and E. coli over time and an absence of Staphylococcus aureus and Listeria monocytogenes at all stages of the covilhete's processing, showing good hygiene of utensils and hands.In nutritional and physico-chemical terms, the covilhete with 100% vegetable margarine has a higher water content and lower moisture content and pH compared to the traditional covilhete, revealing a greater microbial risk.While the traditional covilhete with In the second phase of the work, 24 covilhetes (3 batches x 2 samples x 4 conditions) were collected after cooking and physico-chemical, nutritional and microbiological parameters were then determined on samples of covilhete with different margarines and with a 20% reduction of each of them in their formulation. In addition, the fatty acid profile was also evaluated, where the retention time of the fatty acids present and the respective fatty acids were determined.Finally, a sensory analysis was carried out with 97 tasters in which 4 types of covilhetes were evaluated.These included a traditional covilhette, a covilhette with a 20 per cent reduction in fat content, a covilhette in which a different margarine was used, including RSPO-MB palm fat, and another with the latter margarine, but with a 20 per cent reduction. In general, there was a reduction in the presence of lactic acid bacteria (LAB), mmesophilic microorganisms and E. coli over time and an absence of Staphylococcus aureus and Listeria monocytogenes at all stages of the covilhete's processing, showing good hygiene of utensils and hands. In nutritional and physico-chemical terms, the covilhete with 100% vegetable margarine has a higher water content and lower moisture content and pH compared to the traditional covilhete, revealing a greater microbial risk. The traditional covilhete with a 20 per cent fat reduction had the lowest salt content compared to the other samples, but a higher protein content. When determining the fatty acid profile of the traditional covilhete, the presence of stearic and oleic fatty acids was detected, while the covilhete with the same margarine but with a 20% reduction also had palmitic fatty acid. On the other hand, in samples whose margarine includes palm fat, stearic and oleic fatty acids predominate. Regarding the sensory analysis of the four formulations, the tasters preferred the traditional covilhete with a lower fat content, which stood out for its crunchy, buttery, yellow appearance and lower salt content in terms of flavour.

Debido al uso excesivo de fertilizantes nitrogenados y fosfatados que se utilizan para la producción de cultivos, se ha visto la necesidad de buscar alternativas como son las bacterias promotoras de crecimiento vegetal, las cuales pueden favorecer la productividad y mejorar la calidad del cultivo de maíz, contribuyendo así a la salud del consumidor, al suelo, al agua y al medio ambiente. De esta manera, el trabajo tuvo como objetivo evaluar las características promotoras de crecimiento vegetal en bacterias aisladas del cultivo de maíz (Zea mays L.)”. Se aislaron 9 bacterias (B1, B2, B3, B4, B5, P1, P2, P3, P4) de la provincia de Picota, distritos de Barranquita y Tingo de Ponaza. Las bacterias fueron aisladas utilizando dos medios de cultivo libres de nitrógeno, MJV y Burk. Sólo 1 cepa no fue capaz de producir ácido indol acético en las condiciones establecidas, las restantes (8 cepas) produjeron AIA en un rango muy variable (desde 1,08 a 11,12 µg AIA/ ml de TSB). El 100 % de las cepas aisladas del cultivo de maíz solubilizaron fosfatos y produjeron sideróforos con una eficiencia mayor de 30 μg/ml, siendo las cepas B1 (Barranquita) y P4 (Tingo de Ponaza) las que mostraron la máxima producción de 171,35 y 151,89 μg/ml, respectivamente. Las metodologías de la presente investigación constituyen “una de las estrategias más empleadas para seleccionar microorganismos con intereses biotecnológicos”. Estos pueden permitir “desarrollar productos alternativos a los fertilizantes de síntesis química y a los” plaguicidas, favoreciendo así, a un incremento en la productividad del cultivo de maíz. | The overuse of nitrogen and phosphate fertilizers in crop production has led to the need to search for alternatives such as plant growth promoting bacteria, which can enhance productivity and improve the quality of corn crops, thus contributing to the health of the consumer, the soil, water and the environment. The objective of this work was to evaluate the plant growth promoting characteristics of bacteria isolated from maize (Zea mays L.)". Nine bacteria (B1, B2, B3, B4, B5, P1, P2, P3, P4) were isolated from the province of Picota, districts of Barranquita and Tingo de Ponaza. The bacteria were isolated using two nitrogen-free culture media, MJV and Burk. Only 1 strain was unable to produce indole acetic acid under the established conditions, the remaining strains (8 strains) produced IAA in a highly variable range (from 1.08 to 11.12 µg IAA/ml TSB). The 100% of the strains isolated from the corn crop solubilized phosphates and produced siderophores with an efficiency greater than 30 μg/ml, with strains B1 (Barranquita) and P4 (Tingo de Ponaza) showing the highest production of 171.35 and 151.89 μg/ml, respectively. The methodologies of the present research constitute "one of the most used strategies to select microorganisms with biotechnological interests". These can allow "developing alternative products to chemical synthesis fertilizers and pesticides", thus favoring an increase in corn crop productivity.

Mestrado em Engenharia Alimentar / Instituto Superior de Agronomia, Universidade de Lisboa. | In recent years the importance of sustainability has increased, and as such the food industry decided to leverage byproducts in a manner that produces more sustainable products. Whey is a nutrient filled byproduct of the dairy industry, and for years it has been used as animal feed or disposed as waste. Whey is quickly degraded by lactic acid bacteria, leading to the necessity of whey preservation or rapid transformation in stable products. Heat is the most commonly used treatment to inactivate microorganisms, however, this procedure reduces the nutritional quality of whey. Alternative non-thermal technologies, such as pulse electric fields (PEF) and ultrasound (US), are a potential alternative that can reduce input cost and improve nutritional quality. The objective of this research was to evaluate the effectiveness of PEF and US technologies for the conservation of whey. For this effect, whey samples were processed at different conditions of PEF and US to evaluate microbial inactivation. The PEF conditions comprised of 5 passages with 16 kV/cm electric field intensity and 55 kJ/kg of specific energy. Between each passage the whey was cooled to 3-4 °C. The US conditions were conducted at constant temperature (thermosonication) with a power output of 70 W, corresponding to an acoustic power density of 8.75 W/mL. Using PEF system no significant reductions in microorganism were detected, proving that the stand-alone PEF treatment applied is ineffective to inactivate Lactococcus lactis in whey. On the contrary, utilizing PEF as a pre-treatment it was possible to detect a reduction in D-value compared with thermal treatment, implying a possible use of PEF to improve whey pasteurization. The thermosonication treatment studied in this work also demonstrated a significant decrease in inactivation time, however this technology has a limitation of 3.5 to 4 log reductions, afterwards the inactivation kinetics follow a normal thermal inactivation. | Nos últimos anos, a importância da sustentabilidade aumentou e, como tal, a indústria alimentar decidiu utilizar subprodutos de forma a produzir produtos mais sustentáveis. O soro de leite é um subproduto rico em nutrientes da indústria dos lacticínios e há anos que é utilizado como alimento para animais ou descartado como resíduo. O soro é rapidamente degradado por bactérias lácticas, levando à necessidade de conservar o soro ou rapidamente transformá-lo em um produto estável. O calor é o tratamento mais utilizado para inativar microrganismos, no entanto no soro este procedimento pode causar coagulação e reduzir a sua qualidade nutricional. Tecnologias alternativas não térmicas, como campos elétricos pulsados (PEF) e ultrassons (US), são uma possível alternativa para a pasteurização com potencial redução do custo energético e benefícios em termos da qualidade nutricional. O objetivo deste estudo foi avaliar a eficiência das tecnologias de PEF e US em termos de inativação microbiana e subsequente conservação do soro. Para este efeito, as amostras de soro foram processadas com diferentes condições de PEF e US para avaliar a inativação microbiana, avaliada com o Lactococcus lactis. As condições do PEF compreenderam 5 passagens com intensidade de campo elétrico de 16 kV/cm e 55 kJ/kg de energia específica. Entre cada passagem, o soro foi arrefecido a uma temperatura entre 3-4 °C. Os ultrassons foram aplicados em combinação com temperaturas moderadas (termossonicação) consumindo uma potência de 70 W, que corresponde a uma densidade de potência acústica de 8.75 W/mL. Relativamente ao sistema PEF, não foram detetadas reduções significativas no microrganismo, provando que o tratamento de PEF sem calor não é eficaz para inativar Lactococcus lactis no soro. No entanto, utilizando o PEF como pré-tratamento registou-se uma redução ligeira no D-value de inativação térmico. O tratamento de termossonicação também demonstrou uma diminuição significativa no tempo de inativação, apesar da observação de um patamar constante de 3.5 a 4 reduções logarítmicas ao fim de algum tempo. | N/A

Tesis doctoral con Mención de "Doctor Internacional" | Programa de Doctorado en Salud Pública y Animal por la Universidad de Extremadura | La compleja interacción entre la microbiota y su hospedador constituye un modelo de estudio que puede ser replicado para el desarrollo lo de nuevas herramientas que contribuyan al control de determinadas enfermedades. Los animales silvestres tienen una microbiota que destaca por ser más diversa y funcional y esta es una fuente de microorganismos beneficiosos que pueden ser explotados industrialmente para la obtención de compuestos bioactivos. En esta tesis doctoral se describen los procedimientos de aislamiento y caracterización de bacterias con propiedades antimicrobianas e inmunomoduladoras de la microbiota de jabalíes, así como los criterios de selección de candidatas a ser utilizadas para el diseño de un pienso funcional. Asimismo, la gran novedad de esta tesis de Doctorado Industrial supone culminar con su investigación aplicada mediante la elaboración de un producto posbiótico que incluye diversos estudios de validación en condiciones experimentales y su ratificación en situaciones reales en sanidad animal, tanto en fauna salvaje como en animales destinados a producción. El método desarrollado ha tenido un impacto significativo sobre la actividad de la empresa INGULADOS, que ha visto incrementada su competitividad en el sector, debido al lanzamiento de una gama de productos, a la creación de una nueva línea de trabajo y un nuevo perfil laboral y a la solicitud de dos patentes de invención. Los estudios de esta tesis doctoral han incrementado el conocimiento disponible sobre la interacción entre el hospedador y su microbiota y arroja grandes prospectivas de futuro a la utilización de elementos innovadores en Sanidad y Producción Animal. | The crosstalk between the microbiota and its host represents a study model that can be replicated for the development of novel tools to control certain diseases. Wild animals harbor a microbiota that overhangs for the greater diversity and functionality. Hence, it is presented as a source of beneficial microorganisms that can be industrially exploited to obtain bioactive compounds. This doctoral thesis describes the procedures for the isolation and characterization of bacteria with antimicrobial and immunomodulatory properties from wild boar microbiota, as well as the criteria for selecting candidates to be used for the design of a functional feed. Similarly, the great novelty of this Industrial Doctorate thesis supposes concluding with its applied research through the elaboration of a postbiotic product. The development of the postbiotic includes several validation studies under experimental conditions and its ratification in real situations in animal health, both in wildlife and livestock. The method developed in this Industrial Doctorate thesis has had a significant impact on the activity of INGULADOS. The company has increased its competitiveness within its sector, since the launch of a range of postbiotic products has favoured the creation of a new line of work and a new job profile and the technology transfer has resulted in the application for two invention patents. The studies of this doctoral thesis have increased the available knowledge on the interaction between the host and its microbiota and show great future prospects for the use of innovative elements in Animal Health and Production. | - Programa de Doctorados Industriales (Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades, DI-17-09603) para su desempeño en INGULADOS SL bajo la tutela de la Universidad de Extremadura. - Subvenciones para contratos para la formación de doctores en empresas (DI-17-09603) del Programa de Doctorados Industriales de la Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades, 2017. - Becas QUERCUS+ para la financiación de formaciones prácticas mediante estancias en el extranjero, 2016-2017. - Proyectos de I+D+i: ..«Alternativa a antibióticos para el control de enfermedades en especies cinegéticas (INMUNOBALANCE)» del Centro para el Desarrollo Tecnológico Industrial (IDI-20201262) y el Ministerio de Ciencia, Innovación y Universidades ..«Nuevos compuestos postbióticos procedentes de ungulados para la mejora del sistema inmune de los corderos (POSBIOLAMB)» de la Consejería de Economía, Ciencia y Agenda Digital de la Junta de Extremadura (IDA2-19-002-3) ..«Interacción sinérgica de antibióticos con nuevos compuestos bioactivos secretados por bacterias» y «Efectos de la administración de elementos inmunomoduladores en rumiantes» del ICEX (España Exportación e Inversiones) y el Ministerio de Industrial, Comercio y Turismo. ..«Caracterización de productos inmunomoduladores para el control de la tuberculosis bovina en fauna salvaje» de la Consejería de Economía e Infraestructuras de la Junta de Extremadura (AA/17-0001-1).