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Rational design and engineering of a microbial cell factory for 3-hydroxypropionic acid production
(Universidade Federal de São Carlos, 2021-04-20) Chaves, Gabriel Luz; Silva, Adilson José da; https://lattes.cnpq.br/3447469350644179; https://lattes.cnpq.br/7063262952154349
The US Department of Energy ranked the 3-hydroxypropionic acid (3-HP) among the Top 10 most promising value-added chemicals that can be derived from biomass in a biorefinery. This acid has great potential to serve as a building block for the industry, serving as raw material for paints, coatings, and polymers. Nevertheless, its production from chemical routes encompasses processes that are highly toxic and environmentally harmful. In this context, fermentative bioprocesses are a promising alternative for 3-HP production. Here, we proposed the obtention of an Escherichia coli strain genetically modified to produce 3-HP through the β-alanine pathway, yet poorly studied. To build an E. coli strain able to produce 3-HP, the genes that encode the last three reactions of the pathway were cloned and combined in the same plasmid (pEbtyGpD): pa0132 from Pseudomonas aeruginosa, ydfG from E. coli, and panD from Corynebacterium glutamicum. This first engineered strain, named PS100, produced up to 0.338 ± 0.044 g/L of 3-HP after 24 h of induction with IPTG using glucose as a carbon source. Surprisingly, cultivations on a mixture of glucose and xylose (1:1 on C-mol basis) yielded a final titer of 1.040 ± 0.050 g/L by this strain, from the same substrate amount. To optimize the production obtained from PS100, new genetic modifications were investigated through in silico optimization of a genome-scale metabolic model of E. coli K-12 MG1655. The model iML1515 was modified to include the heterologous reaction of β-alanine conversion to malonic semialdehyde, and three reactions were identified as potential metabolic targets for enhancing 3-HP production by E. coli cells: the reactions of alanine racemase (ALAR), L-alanine aminotransferase (ALAT), and L-valine transaminase (VALTA). These target reactions were modified in the strain PS100, generating the strain PSO107 that was able to improve nearly 2-fold the final titer of the acid when compared to PS100 in cultivations with glucose as carbon source, reaching 0.743 ± 0.016 g/L of 3-HP. For cultivations with the glucose:xylose mixture, a 10% increment was observed for the PSO107 strain compared to PS100, with the former reaching 1.147 ± 0.015 g/L of 3-HP. These results confirm that the targets predicted by the evolutionary optimizations of the genome-scale metabolic model were assertive and enabled an increment in the final production of 3-HP by the engineered E. coli strain.
Produção acadêmica sobre cultura organizacional em escolas de educação básica no Brasil de 2006-2020
(Universidade Federal de São Carlos, 2021-04-20) Yamazato, Marcelo Oda; Nascente, Renata Maria Moschen; https://lattes.cnpq.br/3742955383665134; https://lattes.cnpq.br/4135953867259858
This dissertation derives from an investigation which was developed within the Study and Research Group on School Organization: Democracy, Human Rights and Principals’ development - DEFORGES. Organizational culture in Brazilian schools was its theme, having as its problem the following question: how is the academic production on organizational culture configured in basic education schools in Brazil? Thus, the general objective was to understand the theoretical and methodological approaches to the subject in the articles, dissertations and thesis that constitute this production and the specific objectives were to map research on this theme from 2006 to 2020, systematizing its theoretical references, methodological procedures, and conclusions, and to analyze the theoretical matrices referring to culture in these studies. The methodological approach was the bibliographic one, carried out on SciELO and CAPES Theses and Dissertations Repository digital databases. Critical theoretical framework guided the results analysis, which indicated that: the most used research design was the case study; the most used data collection instrument was document analysis followed by semi-structured interviews; the most investigated level of education was elementary school followed by high school in public municipal and state institutions. The references of Edgar Schein, António Nóvoa and Heloísa Lück also stood out. In addition, it was possible to observe that the organizational culture was worked in relation to several topics, the most frequent being school management, change processes, democratic management, and school performance. In most of the works, the study of organizational culture was developed to analyze the school reality, relating to, and facilitating investigations on several other topics, being able to show the subjects' autonomy and their possibilities of construction and reconstruction of organizational culture. It was concluded that organizational culture is a concept that can contribute to research on schools, especially those that seek to investigate their dynamics, functioning and relationships. In addition, it became evident that organizational culture in the context of Brazilian education is still a yet to be explored theme that has the potential to subsidize school administration in its daily practices.
Resultados para o modelo de rumor de Maki-Thompson em árvores
(Universidade Federal de São Carlos, 2021-04-20) Speroto, Adalto; Vargas Júnior, Valdivino; https://lattes.cnpq.br/1795859800919467; Rodríguez, Pablo Martín; https://lattes.cnpq.br/6412853511887386; https://lattes.cnpq.br/0457367057344704
In this work, we study the Maki-Thompson rumor model on infinite homogeneous trees which is formulated as a continuous-times Markov chain. This model can be defined as a system of interacting particles representing the spread of a rumor by individuals in a homogeneous tree. We assume that each individual can belong to one of three classes in a population represented by: ignorants, spreaders and stifles. A spreader tells the rumor to any of its ignorant (nearest) neighbors at a constant rate. On the other hand, also at the same rate, a spreader becomes a stifler after interact with other spreader (nearest neighbors) or a stifler. Still in this work, we extend our analysis to two generalizations, in the first one we assume that each propagator stops spreading the rumor right after being involved in a certain number of failed attempts and in the second we extend the Maki-Thompson model to Independent and identically distributed random trees. We study sufficient conditions under which the rumor either becomes extinct or survives with positive probability.