ABSTRACT IMPROVED MICROALGAL BIOMASS HARVESTING USING OPTIMIZED ENVIRONMENTAL CONDITIONS AND BACTERIAL BIOFLOCCULANTS DEREK CONTE MANHEIM The cost and energy balance of microalgae biofuel production is sensitive to the algae harvesting method, among many other factors. Bioflocculation and settling of suspended microalgae cultures is a harvesting method with potentially low cost and energy input. However, bioflocculation (the spontaneous flocculation of algal cells without chemical addition) has not been a reliable process with cultures grown in ponds. To provide insights to help improve algae settling, factors affecting the settling of algae were investigated in the laboratory using pure cultures of two common microalgae species: Scenedesmus sp. and Chlorella vulgaris. Bioflocculation of these algae was studied with and without the addition of bioflocculants produced by the bacterium, Burkholderia cepacia, to improve settling efficiencies. The bioflocculant produced by this bacterium was used in two different forms: a cell suspension including capsular and dissolved extracellular polymeric substance (EPS) components of B. cepacia, and dialyzed filtrate of the bacterial culture (only dissolved EPS fraction). The effects of algal growth phase, mixing time, bioflocculant dose, and environmental conditions such as pH and nutrient deprivation of bacterial bioflocculant cultures on settling of the algae species were studied. Settling characteristics were different for the two algae cultures, and their settling was affected differently by the many factors studied. Scenedesmus settling was best in later growth stages, while Chlorella settled much better in early growth phases. Addition of B. cepacia cells as a bioflocculant improved settling of Scenedesmus, with the greatest effect during mid to late exponential growth of the Scenedesmus. In contrast, addition of B. cepacia filtrate as a bioflocculant best improved Chlorella settling during stationary growth of Chlorella. Longer mixing times (contact time between the algae cells and bacterial bioflocculant) improved the settling of Scenedesmus, while Chlorella settled better with a shorter mixing time. Reducing the pH to 3 (a typical isoelectric point for microalgae) improved the settling of both algae cultures, with and without bioflocculant addition. Increasing the pH to 11 autoflocculated Scenedesmus cultures, but not Chlorella cultures, at early growth stages. EPS produced by the algae, bacteria, and wastewater organisms was quantified using dialysis separation followed by total organic carbon (TOC) analysis. Wastewater organisms were included because wastewater is a potential growth medium for biofuel algae. Improved settling of both species of algae depended on both the quantity and type of EPS (dissolved or capsular) produced by both the bacterial bioflocculant, and the algae themselves. Scenedesmus settled the best during late growth phases while its own EPS production was high, and combined EPS (capsular and dissolved) from B. cepacia improved settling at a higher dosage of bacterial cells to algae (1:2 B. cepacia cells to algae cells). Since Chlorella settling was not improved at later growth stages when its own EPS production was greatest, it appears that Chlorella’s settling rate was less affected by the production of its own EPS. For Chlorella, B. cepacia EPS addition (capsular and dissolved) was effective only in low doses (1:6 B. cepacia cells to algae cells). Settling results with the addition of bacterial bioflocculants with the pure algae cultures were compared to settling results of lab experiments with algae pondwater sampled from high-rate algae ponds (HRAPs). These algae samples were used to test the addition of return activated sludge (RAS) to improve settling. RAS addition improved the settling of Chlorella, which was the dominant algae species in the HRAP during the time of this study, at two different doses (a ratio of RAS to algae pond water of 1:3 and 1:6). Nutrient deprivation of B. cepacia cells before use as a bioflucculant was found to improve settling for Scenedesmus, especially during early phases of growth when EPS production of Scenedesmus was low. The EPS produced by the starved bacterial cells was about 30% greater than that produced by cultures which were not nutrient-limited. For the bacterial cultures, EPS production peaked at mid stationary phase for non-starved cultures and during early stationary phase for starved cultures. Chlorella settling improved in early growth with starved bacterial cell addition and in later growth with non-starved bacterial cell addition. These results suggest that the settling of microalgae can vary dramatically by species and that the settling of different species is affected differently by growth phase and environmental conditions. In addition, species of algae respond differently to addition of bacterial bioflocculants. Given the dramatically different settling behavior of the two species of algae used in this research, more research should be directed to studying settling of other microalgal species. Based on this research, the use of bacterial bioflocculants is promising for improving algae settling and may contribute to the development of a reliable, low cost harvesting process for commercial biofuel production from microalgae.

I en tid där allt fler företag lämnar emissionsbesked, finns det genom tidigare forskning relativt tydliga tecken på hur aktiemarknaden reagerar. Däremot råder tvetydighet gällande de emitterande företagens prestationer, när det kommer till det operativa resultatet. Dessutom är ämnet tämligen outforskat på den svenska marknaden. Syftet med denna studie är därför att undersöka hur det operativa resultatet för emitterande företag på Nasdaq Stockholm påverkas i samband med nyemission. Dessutom ämnar studien att förklara huruvida faktorerna emissionstyp, onormala investeringar och marknadstiming har en inverkan på prestationen. Detta har undersökts utifrån teorin om informationsasymmetri, agentteorin och teorin om fritt kassaflöde. Från studiens urvalsram på 274 emissioner som genomförts på Nasdaq Stockholm mellan 2015-2020 har ett slumpmässigt stratifierat urval genomförts. Utifrån dessa har 100 nyemissioner undersökts, fördelat på 52 riktade emissioner och 48 företrädesemissioner. Tillsammans med urvalet har även en kontrollportfölj med matchande icke-emitterande företag baserat på sektor och storlek studerats. Det operativa resultatet hänvisar i denna studie till nyckeltalen ROA och EPS, vilka har undersökts två år inför emission och två år efter. Genom Mann Whitney U test har studiens empiri testats statistiskt för att utreda hur prestationen har påverkats. Studiens resultat visar att emitterande företag på Nasdaq Stockholm uppvisar tydliga nedgångar i dess operativa resultat, vilket även är signifikant i jämförelse med kontrollportföljen. Utifrån studiens oberoende variabler, indikerar resultaten att emissionstyp har en inverkan på det operativa resultatet. Vidare genomförs konstaterandet att onormala investeringar delvis har en negativ påverkan medan inget stöd ges för marknadstiming.

Byggbranschen står för ungefär en femtedel av växthusgasutsläppen i Sverige. Lagstiftning för obligatorisk klimatdeklaration med syftet att minska en byggnads klimatpåverkan trädde i kraft i januari 2022. En Environmental Product Declaration (EPD) är en tredjepartsgranskad miljödeklaration baserad på en Life Cycle Assessment (LCA) och i enlighet med Product Category Rules (PCR). Så kallade programoperatörer är företag vilka utfärdar både PCR:er och EPD:er. En EPD beskriver en produkts resursanvändning, relaterade utsläpp av miljöpåverkande ämnen samt avfallsgenerering och infrastruktur är en parameter som påverkar dessa kategorier. Infrastruktur motsvarar bland annat de maskiner, anläggningar och transporter som är nödvändiga för framställningen av en produkt och skillnader i hur infrastruktur modelleras i en EPD är huvudfrågeställningen i det här arbetet. Hur detta modelleras är svårt att uppskatta på ett konsekvent och rimligt sätt och programoperatörers förhållningssätt till detta påverkar bedömningen av en byggprodukts miljöpåverkan. EPD:er bör vara tillförlitliga och jämförbara med varandra, men det är inte säkert att programoperatörer har använt sig av samma kriterier för miljödeklarationerna. Det undersöktes vilka LCA-databaser (vilka bidrar med indata) som programoperatörernas system baseras på samt hur infrastruktur hanteras. Vidare vilka databaser som tillåts, vilken kvalitet som krävs av data i dessa samt skillnader i miljöpåverkan i EPD:er, vilket uttrycks som indikatorer för exempelvis klimatpåverkan av växthusgaser och försurning. Huvudsyftet med arbetet har varit att ge en bild av programoperatörers uppfattning om infrastrukturens påverkan på en EPD för att kunna bidra till och nyansera diskussionen kring detsamma. Dessutom introduceras metodiken för LCA och EPD för att öka förståelsen i ämnet. För att samla underlag för att besvara frågeställningarna kontaktades programoperatörer i första hand. Frågor gick ut i två omgångar till samtliga medlemmar av Eco Platform. Publicerade artiklar med exempelvis sökorden ’EPD’ och ’infrastructure’ har tjänat som underlag till enkätundersökningen. Standarder såsom EN 15804 och styrdokument från programoperatörer har studerats för att verifiera svaren av undersökningen. Slutligen studerades fem EPD:er för Portland-cement utgivna av programoperatörerna som var med i enkätundersökningen. De två mest frekvent använda databaserna GaBi och ecoinvent används av de flesta LCA-utövare enskilt eller parallellt med varandra. Andra LCA-databaser är även oftast godkända för användning. Infrastruktur är en parameter som i samtliga fall räknas med, eller tillåts räknas med, i det fall det finns uppgifter om detta för en specifik byggprodukt. Kravet på datakvalitet med avseende på ålder är antingen fem (tillverkarens data) eller tio år (generiska data). I de fall uppgifter för infrastruktur saknas i den använda databasen kan den inte kompletteras av programoperatörerna och det är dessutom svårt eller inte möjligt för dem att kontrollera att generiska data stämmer. Samtidigt tycker en majoritet att infrastruktur bör inkluderas vid framtagandet av EPD:er och det finns stor tillit till LCA-databaserna. Infrastruktur har en tydlig påverkan på en produkts miljöpåverkan och särskilt på indikatorn utarmning av icke-fossila resurser. Infrastruktur kan också vara en av faktorerna till varför de studerade EPD:erna uppvisade så skild miljöpåverkan. Skulle programoperatörer antingen enas kring hur de regler vilka ligger till grund för en EPD tolkas eller besluta sig för att inte inkludera faktorn infrastruktur skulle avvikande miljöpåverkan i EPD:er till följd av infrastruktur kunna undvikas. / As the building industry in Sweden accounts for about one fifth of greenhouse gas emissions and there is new legislation in place mandating the climate declaration of buildings, Environmental Product Declarations (EPDs) are increasingly important. Based on a Life Cycle Assessment (LCA) and Product Specific Rules (PRC), these climate declarations are audited and published by so called program operators. These may differ in how they allow infrastructure (the necessary machines, and facilities etc. to produce a product) to be interpreted and handled as a parameter forming the basis of an EPD. What has been investigated is what LCA-databases program operators use, and how infrastructure is treated in the process of developing an EPD, further questions being: do they include it, and do they feel comfortable with the data they are provided with. All European program operators were contacted to collect the answers through a questionnaire based on a literature search with keywords such as ‘EPD’ and ‘infrastructure’. Standards such as EN 15804 and program operator documents served to confirm the answers. GaBi and Ecoinvent are the two main databases used and infrastructure is necessarily treated as is since there is generally no way for program operators to verify the data themselves. There is a great degree of trust in data provided to program operators and as infrastructure is effortless to include, it is included whenever possible and permissible. Infrastructure influences a product’s environmental footprint significantly. Program operators need to interpret associated standards uniformly in developing EPDs or decide to entirely exclude the factor of infrastructure. Otherwise EPDs would be rendered incomparable.

Part I: Signaling Role of the Sensor Kinase RetS in Biofilm formation Regulation of Pseudomonas aeruginosa-<br />The opportunistic human pathogen Pseudomonas aeruginosa causes both acute and chronic infections in predisposed individuals. Acute infections require a functional Type Three Secretion System (TTSS), which mediates the translocation of select cytotoxins into host cells. Chronic infections, the leading cause of death among cystic fibrosis patients, are characterized by drug-resistant biofilms formation. To regulate gene expression, Pseudomonas aeruginosa utilizes two-component regulatory systems (TCS). Specifically, we focus on the TCS signaling kinase RetS, which is a critical repressor of biofilm formation. The signaling mechanism of RetS is unusual. According to recent findings and one hypothesis, RetS employs a novel signaling mechanism involving direct binding to the signaling kinase GacS, thereby repressing the GacS-induced biofilm formation. RetS is believed to be regulated by the interaction of its periplasmic sensory domain (RetSperi) with an unknown ligand. As such, RetSperi is a potential drug target. We hypothesized that ligand-binding shifts the equilibrium between the formation of a RetS homo-dimer and the RetS-GacS complex by tuning the homo-dimerization of the RetSperi. While the molecular signal that regulates RetS is unknown, our structural studies of the sensory domain suggest that this ligand is a carbohydrate-based moiety. Unchanged biofilm-EPS production phenotype of RetSperi ligand binding site mutants indicates that the natural ligand is not from Pseudomonas aeruginosa.<br />Additional experiments unambiguously determined that the sensory domain forms a stable homodimer. Adding to the complexity of the system, we have identified<br />two possible dimer interfaces in our in vitro assays. However, inconsistent with the current model, elimination of RetSperi results in a slightly increased biofilm EPS production phenotype. Therefore, with the previous demonstration that RetS is able to dephosphorylate GacS, we propose an alternative hypothesis: the RetS kinase domain serves as a phosphatase for phosphorylated GacS; this phosphatase activity is tuned by signaling sensing on RetSperi. Finally, to provide an important piece of information for understanding the molecular basis of RetS-GacS signaling, we have developed a crystallization-based structure determination strategy in order to reveal the precise RetS-GacS interaction pattern.<br /><br />PartII: The catalytic domain of the germination-specific lytic transglycosylase SleB from Bacillus anthracis displays a unique active site topology-<br />germination-specific lytic enzymes (GSLEs) that degrade the unique cortex peptidoglycan to permit resumption of metabolic activity and outgrowth. We report the first crystal structure of the catalytic domain of a GSLE, SleB. The structure revealed a transglycosylase fold with unique active site topology and permitted identification of the catalytic glutamate residue. Moreover, the structure provided insights into the molecular basis for the specificity of the enzyme for muramic-"?lactam-containing cortex peptidoglycan. The protein also contains a metal-binding site that is positioned directly at the entrance of the substrate-binding cleft. / Ph. D.

In this Doctoral Thesis the study of the influence of the operating parameters of the activated sludge process on the physical and chemical characteristics of the mixed liquor, from different membrane bioreactors (MBR), has been carried out. In addition, an optical characterization of the mixing liquor has been performed. In order to achieve the above mentioned aim, samples of the mixed liquor from an MBR treating municipal wastewater were first analysed and then, the characteristics of two MBR mixed liquors treating the leachates from two treatment plants of the organic fraction of municipal solid waste (OFMSW) were evaluated. It is noteworthy that the difference between the two industrial MBR lies on the feeding (inlet) to the MBR, which is determined by the treatment performed to the OFMSW, since one of them consists of a wet anaerobic digestion (MBR-LS) and the other of a dry anaerobic digestion (MBR-HS), so that the latter leachate contains higher concentration of suspended solids in its composition. For the chemical characterization of the mixture liquor, the extracellular polymeric substances (EPS) have been analysed. EPS are formed by the sum of extracted extracellular polymeric substances (eEPS) and soluble microbial products (SMP). These substances are considered the main cause of membranes fouling in MBRs and are basically formed by proteins and polysaccharides, which can be both attached to the cell wall and outside the cell, in form of eEPS or SMP. Regarding the physical characterization, in particular it has been analysed and studied the effect on the membrane fouling of the total and volatile suspended solids, the viscosity, the capillary suction time and the particle size, measured through the resistance to filtration. Finally, in the municipal MBR, cell viability with epifluorescence microscopy has been studied, as well as the main components of EPS have been stained by two different methods. In addition, a statistical study has evaluated the effect of the main operating parameters of the MBR on the characterization parameters of the mixed liquor. By means of least squares regression, the operational parameters that influence SMP production in industrial MBR have been studied. The study was completed by evaluating the fouling of an ultrafiltration membrane with proteins extracted from EPS and subsequently purified with ammonium sulphate at different pH values. To this end, different synthetic proteins (bovine serum albumin, casein, haemoglobin and lysozyme) were first analysed and then compared with the proteins extracted from the mixed liquor. Membrane fouling with purified eEPS proteins has also been studied along with sodium alginate added in the same concentration as the proteins. The results obtained demonstrate, firstly, that SMP play an important role in the membrane fouling. The concentration of proteins has been considerably higher than that of carbohydrates both in SMP and in eEPS, although SMP influenced to a greater extent on the filtration of the activated sludge. In addition, it is shown that bacteria under stress conditions, caused for example by increase in conductivity, increase the production of SMP, and therefore, membrane fouling increases. On the other hand, it is concluded that a low hydraulic retention time favours a high carbohydrates concentration and consequently drives to an increase in the viscosity and capillary suction time, also increasing the membrane fouling. / En la presente Tesis Doctoral se ha llevado a cabo el estudio de la influencia de los parámetros de operación del proceso de fangos activos en las características físicas y químicas de los licores de mezcla, procedentes de diferentes biorreactores de membrana (MBR). Además, se ha realizado una caracterización óptica del licor de mezcla. Para ello, en primer lugar se tomaron muestras del licor de mezcla de un MBR que trata aguas residuales urbanas y, a continuación, se evaluaron las características de los licores de mezcla de dos MBR que tratan los lixiviados procedentes de dos plantas de tratamiento de la fracción orgánica de los residuos sólidos urbanos (FORSU). Cabe destacar que la diferencia entre los dos MBR industriales radica en la alimentación (afluentes) al MBR, que viene determinada por el tratamiento que se realiza a la FORSU, ya que uno de ellos consiste en una digestión anaerobia en vía húmeda (MBR-LS) y, el otro, en una digestión anaerobia en vía seca (MBR-HS), por lo que este último lixiviado contiene mayor concentración de sólidos en suspensión en su composición. Para la caracterización química del licor de mezcla, se han analizado las sustancias poliméricas extracelulares (EPS), formadas por la suma de las sustancias poliméricas extracelulares extraídas (eEPS) y los productos solubles microbianos (SMP). Estas sustancias se consideran las principales causantes del ensuciamiento de las membranas del MBR y están formadas básicamente por proteínas y polisacáridos, los cuales pueden estar tanto adheridos a la pared celular como fuera de la célula, en forma de eEPS o SMP. En cuanto a la caracterización física, en concreto se ha analizado y estudiado el efecto en el ensuciamiento de las membranas de los sólidos en suspensión totales y volátiles, la viscosidad, el tiempo de succión capilar y el tamaño de partícula, medido a través de las resistencias a la filtración. Finalmente, en el MBR urbano se ha estudiado la viabilidad celular con microscopía de epifluorescencia, así como se han teñido para su caracterización óptica los principales componentes de las EPS por dos métodos distintos. Además, mediante un estudio estadístico se ha evaluado el efecto de los principales parámetros de operación de los MBR sobre los parámetros de caracterización del licor de mezcla. Mediante regresión por mínimos cuadrados se han estudiado los parámetros operacionales que influyen en la producción de SMP en los MBR industriales. El estudio se ha completado evaluando el ensuciamiento de una membrana de ultrafiltración con proteínas extraídas de las EPS y posteriormente purificadas con sulfato amónico, a diferentes valores de pH. Para ello, en primer lugar se han caracterizado diferentes proteínas sintéticas (albúmina de suero bovino, caseína, hemoglobina y lisozima) para compararlas con las proteínas extraídas del licor de mezcla. También se ha estudiado el ensuciamiento de la membrana con las proteínas purificadas de las eEPS junto con alginato de sodio en la misma proporción. Los resultados obtenidos demuestran en primer lugar que los SMP juegan un papel importante en el ensuciamiento de las membranas. Tanto en su composición como en la de las eEPS, la concentración de proteínas determinada ha sido considerablemente mayor que la de carbohidratos, si bien éstos influyen incluso en mayor medida en la filtrabilidad del fango activo. Además, se demuestra que las bacterias bajo condiciones de estrés, causado por ejemplo por aumento de conductividad, aumentan la producción de SMP, y por tanto, se incrementa el ensuciamiento de las membranas. Por otro lado, se concluye que un tiempo de retención hidráulico bajo favorece una concentración elevada de carbohidratos y consecuentemente provoca un aumento de la viscosidad y el tiempo de succión capilar, aumentando también el ensuciamiento de la membrana. / En la present Tesi Doctoral s'ha dut a terme l'estudi de la influència dels paràmetres d'operació del procés de fangs actius en les característiques físiques i químiques de licors de mescla, procedents de diferents biorreactors de membrana (MBR). A més, s'ha realitzat una caracterització òptica del licor de mescla. Per a això, en primer lloc es van prendre mostres del licor de mescla d'un MBR que tracta aigües residuals urbanes i, a continuació, es van avaluar les característiques dels licors de mescla de dos MBR que tracten els lixiviats procedents de dues plantes de tractament de la fracció orgànica dels residus sòlids urbans (FORSU). Cal destacar que la diferència entre els dos MBR industrials radica en l'alimentació (afluents) al MBR, que ve determinada pel tractament que es realitza a la FORSU, ja que un d'ells consisteix en una digestió anaeròbia en via humida (MBR-LS) i, l'altre, en una digestió anaeròbia en via seca (MBR-HS), per la qual cosa este últim lixiviat conté major concentració de sòlids en suspensió en la seua composició. Per a la caracterització química del licor de mescla, s'han analitzat les substàncies polimèriques extracel¿lulars (EPS), formades per la suma de les substàncies polimèriques extracel¿lulars extretes (eEPS) i els productes solubles microbians (SMP). Estes substàncies es consideren les principals causants de l'embrutiment de les membranes del MBR i estan formades bàsicament per proteïnes i polisacàrids, els quals poden estar tant adherits a la paret cel¿lular com fora de la cèl¿lula, en forma d'eEPS o SMP. Quant a la caracterització física, en concret s'ha analitzat i estudiat l'efecte en l'embrutiment de les membranes dels sòlids en suspensió totals i volàtils, la viscositat, el temps de succió capil¿lar i la grandària de partícula, mesurat a través de les resistències a la filtració. Finalment, en el MBR urbà s'ha estudiat la viabilitat cel¿lular amb microscòpia d'epifluorescència, així com s'han tenyit per a la seua caracterització òptica els principals components de les EPS per dos mètodes distints. A més, per mitjà d'un estudi estadístic s'ha avaluat l'efecte dels principals paràmetres d'operació dels MBR sobre els paràmetres de caracterització del licor de mescla. Per mitjà de regressió per mínims quadrats s'han estudiat els paràmetres operacionals que influeixen en la producció de SMP en els MBR industrials. L'estudi s'ha completat avaluant l'embrutiment d'una membrana d'ultrafiltració amb proteïnes extretes de les EPS i posteriorment purificades amb sulfat amònic, a diferents valors de pH. Per a això, en primer lloc s'han caracteritzat diferents proteïnes sintètiques (albúmina de sèrum boví, caseïna, hemoglobina i lisozima) per a comparar-les amb les proteïnes extretes del licor de mescla. També s'ha estudiat l'embrutiment de la membrana amb les proteïnes purificades de les eEPS junt amb alginat de sodi en la mateixa proporció. Els resultats obtinguts demostren en primer lloc que els SMP juguen un paper important en l'embrutiment de les membranes. Tant en la seua composició com en la de les eEPS, la concentració de proteïnes determinada ha sigut considerablement major que la de carbohidrats, si bé estos influeixen inclús en major grau en la filtrabilidad del fang actiu. A més, es demostra que els bacteris baix condicions d'estrès, causat per exemple per augment de conductivitat, augmenten la producció de SMP, i per tant, s'incrementa l'embrutiment de les membranes. D'altra banda, es conclou que un temps de retenció hidràulic baix afavoreix una concentració elevada de carbohidrats i conseqüentment provoca un augment de la viscositat i el temps de succió capil¿lar, augmentant també l'embrutiment de la membrana. / Zuriaga Agustí, E. (2017). Influencia de las características físicas y químicas del licor de mezcla en Bioreactores de Membrana y su correlación con los parámetros de operación en aguas residuales urbanas e industriales [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90512

Myxococcus xanthus, a Gram-negative bacterium with a developmental cycle, displays a type IV pili (TFP) mediated surface motility known as social (S) gliding. Beside the polarly localized TFP, the fibril or extracellular polysaccharide (EPS) is also required for S-motility to function. It is proposed that S-motility, along with the related bacterial twitching motility in other species, is powered by TFP retraction. EPS is proposed to anchor and trigger such retractions in M. xanthus. EPS production is known to be regulated by TFP and the Dif signal transduction pathway. Two genetic screens were performed previously to identify additional genes important for EPS production. The first was for the isolation of pilA suppressors, the second for the identification of mutants underproducing EPS in a difA suppressor background. Both screens identified transposon insertions at the stk locus. In particular, StkA, a DnaK homolog, was identified as a possible negative regulator of EPS production by a stkA transposon insertion that suppressed a pilA mutation. A stkB transposon insertion was found to have diminished EPS production in a difA suppressor background. In this study, in-frame deletion mutants of the five genes at the stk locus, stkY, stkZ, stkA, stkB and stkC, were constructed and examined. In addition, mutations of rbp and bskL, two genes downstream of the stk locus, were constructed. Like transposon insertions, the stkA in-frame deletion resulted in overproduction of EPS. The stkB and to a less extent the stkC mutants underproduced EPS. Mutations in the other genes had no obvious effects on EPS production. Genetic epistasis suggests that StkA functions downstream of TFP and upstream of the Dif sensory proteins in EPS regulation in M. xanthus. Epistasis analysis involving stkB was inconclusive. It is unresolved whether StkB plays a role in the biosynthesis or the regulation of EPS production in M. xanthus. / Master of Science

No description available.

O estudo do comportamento de estruturas em situação de incêndio tem se tornado cada vez mais importante devido às graves consequências de incêndios que têm ocorrido no Brasil e em outros países. Por esse motivo, este trabalho tem como objetivo estudar o comportamento residual do concreto com pérolas de EPS sob altas temperaturas, pois se pretende utilizar esse concreto em painéis e em lajes pré-moldadas para a construção de edifícios de pequeno e de médio porte, por ele ser um concreto muito leve, com massa específica em torno de 1170 kg/m3, um pouco menos da metade da relativa ao concreto convencional. Para este estudo, foram utilizados corpos de prova cilíndricos e prismáticos, seguindo recomendações nacionais e internacionais. As análises foram realizadas para 200ºC, 400ºC e 600ºC, e foram avaliadas: massa específica, resistência à compressão, módulo de elasticidade estático, módulo de elasticidade dinâmico, resistência à tração por compressão diametral, resistência à tração na flexão e fator de tenacidade. Para esses dois últimos, foram utilizadas fibras de aço nas seguintes taxas: 0,3%, 0,6% e 0,9%. Os resultados foram comparados com os de concreto com EPS em temperatura ambiente e com os de concreto convencional, que já tem alguns resultados disponíveis na literatura técnica. Também foi realizada uma análise térmica numérica, utilizando o software ABAQUS 14, para calibrar duas propriedades: calor específico e condutividade térmica. Para isso, foram utilizados resultados obtidos na análise experimental. Os resultados numéricos e experimentais foram coerentes com os esperados. Os experimentais apresentaram redução de valor à medida que a temperatura aumentava, e comportamento pior em comparação ao concreto convencional. A adição de fibras aumentou a resistência à tração na flexão e também a tenacidade, tanto em temperatura ambiente quanto em temperaturas elevadas. / The study of the structures behavior in fire has become increasingly important due to the serious consequences of fires that have occurred in Brazil and in other countries. Therefore, this work aims to study the residual behavior of concrete with EPS beads under high temperatures, because it is intended to use it in panels and precast slabs for the construction of small and medium-sized buildings, for it is a very light concrete, with a density around 1170 kg/m3, slightly less than half that of conventional concrete. For this study, cylindrical and prismatic specimens were used, following national and international standards. The analyses were carried out to 200°C, 400°C and 600°C, and were evaluated: density, compression strength, static modulus of elasticity, dynamic modulus of elasticity, splitting tensile strength, flexural tensile strength, and toughness factor. For the latter two, steel fibers were used at the following rates: 0.3%, 0.6% and 0.9%. The results were compared with those of concrete with EPS at room temperature, and with conventional concrete which already has some results available in the technical literature. A numerical thermal analysis was also performed, using ABAQUS 14 software, to calibrate two properties: specific heat and thermal conductivity. For this, results obtained in the experimental analysis were used. The numerical and experimental results were consistent with those expected. The experimental results showed reduction of value as temperature increased, and worst behavior in comparison to ordinary concrete. The addition of fibers increased tensile strength in bending and also the toughness, both at room temperature and at elevated temperatures.

Os objetivos deste trabalho foram avaliar o desempenho do reator anaeróbio operado em batelada seqüencial quando submetido ao aumento progressivo da concentração de glicose e estimar os parâmetros cinéticos da degradação da glicose. Inicialmente o reator foi operado com ciclos de 8 horas, tratando glicose nas concentrações, aproximadas, de 500, 1000 e 2000 mg/L. Não foi detectada glicose no efluente nas três condições. O reator operou de maneira estável, tratando aproximadamente 500 mg/L de glicose, com eficiência na remoção da DQO filtrada entre 93% e 97%. Na operação com concentrações de glicose no afluente próximas de 1000 mg/L e 2000 mg/L, observou-se instabilidade operacional, principalmente devido à produção de polímeros extracelulares (EPS) que comprometeram a hidrodinâmica e a transferência de massa no sistema. Os valores médios da concentrações de ácidos voláteis no efluente foram de 159 ± 72 mg/L e 374 ± 92 mg/L, respectivamente. Aos perfis de concentração de glicose foi ajustado modelo de primeira ordem, enquanto que um modelo modificado, contemplando concentração residual de matéria orgânica, foi ajustado aos perfis temporais de DQO. Para verificar a formação do EPS, operou-se o reator com 3 horas de ciclo nas concentrações, aproximadas, de 500 e 1000 mg/L. Esta fase teve como objetivo verificar a hipótese, segundo a qual, a produção de EPS seria resultado da exposição da biomassa a baixas concentrações de matéria orgânica por longo período. Dessa forma, reduzindo o tempo de ciclo, a exposição a baixas concentrações também seria reduzida. No entanto, embora o reator tenha operado com relativa estabilidade, verificou-se formação de grande quantidade de EPS logo na primeira condição operacional, com aproximadamente, 500 mg/L de glicose no afluente, indicando que a hipótese não estava correta. / The main objectives of this study were to evaluate the performance of the anaerobic sequencing batch reactor when subjected to a progressive increasing of the influent glucose concentration and estimate the kinetic parameters of glucoses degradation. Initially the reactor was operated with 8-hour cycles, treating glucose at concentrations of 500, 1000 and 2000 mg/L. Glucose was not detected in the effluent in all these three conditions. The reactor showed operating stability treating glucose concentration of approximately 500mg/L, with efficiencies between 93% to 97% in the filtrated COD removal. In the operation with glucose concentrations of 1000 mg/L and 2000 mg/L, approximately, it could be noticed an operational instability, caused mainly by a production of extracellular polymers (EPS) leading to hydrodynamic and mass transfer problems in the reactor. The mean values of volatile acids concentration in the effluent were about 159 ± 72mg/L and 374 ± 92mg/L, respectively. A first order model was adjusted to glucose concentration profiles, and a modified model, including a residual concentration of substrate, was adjusted to COD temporal profiles. To verify the EPS formation, the reactor was operated with 3-hour cycle in the concentrations of 500 and 1000 mg/L This stage had the objective of verifying if the EPS production would result from the exposure of the biomass to low concentration of substrate for a long period of time. Thus, reducing the time cycle, the exposure to low concentrations would also be reduced. Nevertheless, even with the reactor operating with relative stability, the hypotheses could not be verified due the formation of a large amounts of EPS right in the first operational condition with approximately to 500 mg/L of glucose in the influent, showing that the hypothesis was not right.

O estudo do comportamento de estruturas em situação de incêndio tem se tornado cada vez mais importante devido às graves consequências de incêndios que têm ocorrido no Brasil e em outros países. Por esse motivo, este trabalho tem como objetivo estudar o comportamento residual do concreto com pérolas de EPS sob altas temperaturas, pois se pretende utilizar esse concreto em painéis e em lajes pré-moldadas para a construção de edifícios de pequeno e de médio porte, por ele ser um concreto muito leve, com massa específica em torno de 1170 kg/m3, um pouco menos da metade da relativa ao concreto convencional. Para este estudo, foram utilizados corpos de prova cilíndricos e prismáticos, seguindo recomendações nacionais e internacionais. As análises foram realizadas para 200ºC, 400ºC e 600ºC, e foram avaliadas: massa específica, resistência à compressão, módulo de elasticidade estático, módulo de elasticidade dinâmico, resistência à tração por compressão diametral, resistência à tração na flexão e fator de tenacidade. Para esses dois últimos, foram utilizadas fibras de aço nas seguintes taxas: 0,3%, 0,6% e 0,9%. Os resultados foram comparados com os de concreto com EPS em temperatura ambiente e com os de concreto convencional, que já tem alguns resultados disponíveis na literatura técnica. Também foi realizada uma análise térmica numérica, utilizando o software ABAQUS 14, para calibrar duas propriedades: calor específico e condutividade térmica. Para isso, foram utilizados resultados obtidos na análise experimental. Os resultados numéricos e experimentais foram coerentes com os esperados. Os experimentais apresentaram redução de valor à medida que a temperatura aumentava, e comportamento pior em comparação ao concreto convencional. A adição de fibras aumentou a resistência à tração na flexão e também a tenacidade, tanto em temperatura ambiente quanto em temperaturas elevadas. / The study of the structures behavior in fire has become increasingly important due to the serious consequences of fires that have occurred in Brazil and in other countries. Therefore, this work aims to study the residual behavior of concrete with EPS beads under high temperatures, because it is intended to use it in panels and precast slabs for the construction of small and medium-sized buildings, for it is a very light concrete, with a density around 1170 kg/m3, slightly less than half that of conventional concrete. For this study, cylindrical and prismatic specimens were used, following national and international standards. The analyses were carried out to 200°C, 400°C and 600°C, and were evaluated: density, compression strength, static modulus of elasticity, dynamic modulus of elasticity, splitting tensile strength, flexural tensile strength, and toughness factor. For the latter two, steel fibers were used at the following rates: 0.3%, 0.6% and 0.9%. The results were compared with those of concrete with EPS at room temperature, and with conventional concrete which already has some results available in the technical literature. A numerical thermal analysis was also performed, using ABAQUS 14 software, to calibrate two properties: specific heat and thermal conductivity. For this, results obtained in the experimental analysis were used. The numerical and experimental results were consistent with those expected. The experimental results showed reduction of value as temperature increased, and worst behavior in comparison to ordinary concrete. The addition of fibers increased tensile strength in bending and also the toughness, both at room temperature and at elevated temperatures.