Teniendo en cuenta el número de industrias alimentarias afectadas por el desarrollo de biofilms, es imprescindible un análisis integral e interdisciplinario de los factores que intervienen en su formación a fin desarrollar estrategias de remoción o prevención de estos. En esta tesis se propuso como objetivo principal profundizar el conocimiento sobre la adhesión, formación y producción de metabolitos en los biofilms formados por levaduras, principales deteriorantes de la industria productora de jugos, en presencia de bacterias patógenas pertinentes a la seguridad de los jugos de frutas, a fin de evaluar posibles estrategias de biocontrol. En el Capítulo I, se analizaron los biofilms multiespecie formados por levaduras y su asociación con bacterias patógenas, basándose en la hipótesis de que las levaduras presentes en la microbiota residente de las superficies de los equipos de producción de jugos de frutas pueden favorecer la persistencia de las bacterias a través de la formación de biofilms. Inicialmente, se llevaron a cabo estudios de los parámetros relacionados con la formación de biofilms de Listeria monocytogenes. Los resultados demostraron que Listeria exhibe un carácter altamente hidrofóbico, es móvil, produce curli y celulosa, es viable en jugo de manzana y se adhiere al acero inoxidable (AI) a 25 oC. Seguidamente, se describieron los biofilms formados por Rhodotorula mucilaginosa, Candida tropicalis, Candida krusei y Candida kefyr, en presencia de L. monocytogenes, Salmonella enterica o Escherichia coli O157:H7, sobre AI y membranas de ultrafiltración (MUF), empleadas para la clarificación de los jugos. Los análisis sobre los biofilms se realizaron empleando técnicas de recuento en placa, microscopía de fluorescencia y microscopía electrónica de barrido. Los resultados revelaron que las estructuras levaduriformes (pseudohifas, blastoporas) proporcionan un entorno propicio para el anclaje y la adhesión de las bacterias patógenas, convirtiéndose así en un nicho elegible para su permanencia en un ambiente que simula la producción de jugos de frutas. En el Capítulo II, se exploró la actividad inhibitoria y antibiofilm de Lacticaseibacillus rhamnosus GG ATCC 53103 (LGG) y Lactobacillus casei ATCC 393 frente a L. monocytogenes, S. enterica y E. coli O157:H7. Se evaluaron dos estrategias de biocontrol: competencia, en la cual tanto las células de Lactobacillus como las bacterias patógenas colonizan simultáneamente la superficie de AI; y exclusión, donde se forma un biofilm protector con células de Lactobacillus sobre la superficie de AI previo a la incorporación de las bacterias patógenas. Ambas especies de Lactobacillus: presentaron alta capacidad adhesiva sobre AI, sin alterar los parámetros fisicoquímicos del jugo de manzana. Además, estas cepas mitigaron la proliferación y adhesión de las bacterias patógenas hasta niveles no detectables en AI. Estos resultados sugieren que las cepas de Lactobacillus estudiadas podrían ser candidatas prometedoras para la formación de biofilms protectores en entornos de producción de jugos, ofreciendo una estrategia efectiva para controlar la adhesión microbiana en superficies relacionadas con la industria alimentaria. Con el objetivo de reducir o prevenir la colonización de las levaduras en las superficies y, de este modo, evitar la adhesión de bacterias patógenas que puedan entrar al sistema de producción de jugos de frutas, en el Capítulo III se evaluó la eficacia de moléculas quorum sensing (MQS) producidas por levaduras y del agente antifúngico natamicina (NAT), que se utiliza habitualmente en la industria alimentaria. En primer lugar, se identificaron compuestos orgánicos volátiles (VOC) en biofilms de levaduras, y cuantificaron en presencia y ausencia de bacterias patógenas afectaba su producción. La técnica de extracción con disolventes y la micro extracción en fase sólida se emplearon para la extracción de COV, seguida de un análisis mediante cromatografía gaseosa acoplada a espectrometría de masas. Los resultados demostraron que los biofilms de C. tropicalis producen farnesol (FAR), tirosol (TIR) y 2- feniletanol (2-FE), tres compuestos reconocidos como MQS. Por otro lado, la presencia de las bacterias patógenas no afectó significativamente (p>0,05) la producción de los COV liberados por las levaduras. En segundo lugar, se analizó el efecto de farnesol 0,06 mM (FAR) en combinación con natamicina 0,01 mM (NAT) sobre biofilms de levaduras y multiespecie formados sobre AI y MUF. Los biofilms tratados con NAT+FAR mostraron inhibición de la filamentación de las levaduras y una alteración significativa de la estructura tridimensional tanto en AI como en MUF. Además, se observó una disminución en la adhesión de L. monocytogenes, S. enterica y E. coli O157:H7 en los biofilms multiespecie. La combinación NAT+FAR podría considerarse un agente de control prometedor para prevenir la formación de biofilms en las líneas de procesamiento de jugo de manzana. / Considering the number of food industries affected by the development of biofilms, a comprehensive and interdisciplinary analysis of the factors involved in their formation is essential to develop strategies for their removal or prevention. The main objective of this thesis was to deepen the knowledge of the adhesion, formation, and production of metabolites in biofilms formed by yeasts, the main spoilage agents in the juice production industry, in the presence of pathogenic bacteria relevant to the safety of fruit juices, to evaluate possible biocontrol strategies. Chapter I examined the association between yeasts and foodborne pathogens in biofilms multispecies, based on the hypothesis that yeasts present in the resident microbiota on the surfaces of fruit juice production equipment may favour the persistence of bacteria through the formation of biofilms. Initially, studies were carried out on parameters related to biofilm formation of Listeria monocytogenes. Results indicate that Listeria has a highly hydrophobic character, is mobile, produces both curli and cellulose, is viable in apple juice, and adheres to stainless steel (SS) at 25 °C. Biofilms formed by Rhodotorula mucilaginosa, Candida tropicalis, Candida krusei, and Candida kefyr in the presence of L. monocytogenes, Salmonella enterica or Escherichia coli O157:H7 on SS and ultrafiltration membranes (UFM), were described. Biofilm analyses were performed using plate counting, fluorescence microscopy and scanning electron microscopy techniques. The results revealed that yeast-like structures (pseudohyphae, blastopores) supply a favourable environment for adhesion and adhesion of pathogenic bacteria, thus becoming an eligible niche for their permanence in an environment that simulates fruit juice production. Chapter II aimed to investigate the inhibitory and antibiofilm efficacy of Lacticaseibacillus rhamnosus GG ATCC 53103 (LGG) and Lactobacillus casei ATCC 393 against L. monocytogenes, S. enterica and E. coli O157:H7. Two biocontrol strategies were evaluated: competition, in which Lactobacillus cells and pathogenic bacteria colonise the SS surface at the same time; exclusion, in which a protective biofilm with Lactobacillus cells is formed on the SS surface and pathogenic bacteria are after incorporated. Both Lactobacillus species adhered to AI, without altering the physicochemical parameters of the apple juice. Furthermore, these strains mitigated the proliferation and adhesion of pathogenic bacteria to undetectable levels on AI. These results suggest that the studied Lactobacillus strains could be promising candidates for the formation of protective biofilms in juice production environments, offering an effective strategy to control microbial adhesion on food industry-related surfaces. To reduce or prevent yeast colonization on surfaces and thus avoid the adhesion of pathogenic bacteria that may enter the fruit juice production system, the efficacy of quorum sensing molecules (QSM) produced by yeasts and the antifungal agent natamycin (NAT), which is commonly used in the food industry, was evaluated in Chapter III. First, it was identified and quantified the volatiles organic compounds (VOC) released by the yeast biofilms, and then, it was assessed whether the presence of pathogenic bacteria affected the production of these metabolites. The solvent extraction technique and solid phase microextraction were used for metabolite extraction, followed by analysis by gas chromatography coupled to mass spectrometry. The results showed that C. tropicalis biofilms produce farnesol (FAR), tyrosol (TIR) and 2-phenylethanol (2-FE), recognized as MQS. On the other hand, the presence of the pathogenic bacteria did not significantly (p>0.05) alter the production of the VOC released by the yeasts. Second, it was evaluated the effect of farnesol 0.06 mM with NAT 0.01 mM on yeast and multispecies biofilms formed on SS and UFM. Biofilms treated with NAT+FAR showed inhibition of yeast filamentation and a significant alteration of the three-dimensional structure of both AI and MUF. In addition, decreased adhesion of L. monocytogenes, S. enterica and E. coli O157:H7 was observed in the multispecies biofilms. The NAT+FAR combination could be considered as a promising control agent to prevent biofilm formation in apple juice processing lines.

[pt] A pesquisa investiga o estatuto das fabulações na criação de transformações individuais e coletivas multiespécie no contexto da emergência climática (e suas interseccionalidades), com foco em histórias criadas por mulheres. Investiga-se um conjunto selecionado de criações artísticas que poderiam ser ditas simpoiéticas, nos termos de Donna Haraway, e que se mostram capazes de deslocar lógicas, disposições e sensibilidades arraigadamente em curso no contexto do Antropoceno. A investigação parte de um estudo do conto Estórias de Camille, do livro Ficar com o problema:fazer parentes no Chthuluceno, da própria Haraway, buscando em seguida ocasiões de cotejo e contágio entre essa história (em certo sentido inaugural) e duas outras fabulações: a obra de arte híbrida Proliferações, de Fabíola Fonseca, e o filme Teko Haxy: ser imperfeita, co-dirigido pela cineasta indígena Patrícia Ferreira Pará Yxapy e pela antropóloga não indígena Sophia Pinheiro. Feito à luz do conceito de simpoiese, o exame conjunto das criações analisadas busca somar-se aos esforços contemporâneos de contraposição às narrativas antropocêntricas (falocêntricas, etnocêntricas, especistas), tanto em suas versões utópicas e salvacionistas, quanto em reações distópicas e apocalípticas. / [en] The research investigates the status of fabulations in the creation of multispecies individual and collective transformations in the context of the climate emergency (and their intersectionalities), focusing on stories created by women. A selected set of artistic creations is investigated that could be said to be sympoietic, in Donna Haraway s terms, and that are capable of displacing logics, dispositions and sensibilities that are deeply rooted in the context of the Anthropocene. The investigation starts from a study of the short story The Camille Stories, from the book Staying with the Trouble: Making Kin in the Chthulucene, by Haraway herself, then looks for occasions of comparison and contagion between this story (in a certain sense, inaugural) and two others fabulations: the hybrid artwork Proliferações, by Fabíola Fonseca, and the film Teko Haxy: ser imperfeita, co-directed by indigenous filmmaker Patrícia Ferreira Pará Yxapy and non-indigenous anthropologist Sophia Pinheiro. Made in light of the concept of sympoiesis, the joint examination of the analyzed creations seeks to add to contemporary efforts to oppose anthropocentric narratives (phallocentric, ethnocentric, speciesist), both in their utopian and salvationist versions, as well as in dystopian and apocalyptic reactions.