Fernanda Palladino

Biotechnological processes are essential for developing economies that aim to stand out in future markets. The use of bioreactors is one of the most important unit operations of biotechnological processes, and real-time monitoring of bioreactors is essential to ensure precise bioprocess control. This review presents different types of bioreactors, sensors, and applications in other sectors. Bioreactors, controlled systems for cultivating microorganisms and cells, are essential tools in various fields, from scientific research to industrial production. The use of a variety of sensors is critical for accurate, real-time monitoring, early problem detection, reproducibility, cost reduction, and increased efficiency. These benefits are being realized in numerous applications, including biofuel production, bioremediation and leaching processes, tissue engineering, and drug manufacturing. Innovations in bioreactor technology are expanding opportunities for a more sustainable and healthier future. By developing new types of bioreactors, integrating advanced sensors, and exploring promising applications, bioreactors are playing a key role in addressing global challenges and sustainably advancing science and technology.

Xylose is the most abundant pentose sugar in lignocellulosic biomass and can be biologically converted into economically important products by microorganisms such as yeasts. This study aimed to characterize the bioconversion of xylose into xylitol and ethanol using four strains of Candida materiae belonging to the Spathaspora clade, which includes yeast species with the potential to convert D-xylose to xylitol and ethanol. Fermentation assays were performed in YPX medium (yeast extract, peptone, xylose 5%) under two oxygen-limiting conditions at inoculum concentrations of 1, 5 and 10 g L^-1. The best results were obtained using a 5 g L^-1 inoculum under moderate oxygen-limiting conditions. C. materiae UFMG-CM-Y480 produced 32.23 g L^-1 of xylitol, yielding 0.743 g g^-1 within 36 h. Different combinations of xylose and glucose (25/25 g L^-1, 40/10 g L^-1, 10/40 g L^-1) were also used to verify the influence of sugars on C. materiae metabolism. Xylitol was preferentially produced in medium containing 40 g L^-1 xylose. C. materiae UFMG-CM-Y480 produced 26.20 g L^-1 of xylitol with a yield of 0.646 g g^-1 in 36 h. Our results showed that C. materiae UFMG-CM-Y480 may convert D-xylose to xylitol with a better fermentative performance than other xylitol-producing yeasts.

The yeast Cyberlindnera xylosilytica UFMG-CM-Y309 has been identified as a promising new xylitol producer from sugarcane bagasse hemicellulosic hydrolysate (SCHH). However, SCHH pretreatment process generates byproducts, which are toxic to cell metabolism, including furans, phenolic compounds, and carboxylic acids, such as acetic acid, typically released at high concentrations. This research aims to reduce acetic acid in sugarcane hemicellulose hydrolysate concomitantly with xylitol production by yeast strain Cy. xylosilytica UFMG-CM-Y309 in a bioreactor by strategically evaluating the influence of volumetric oxygen transfer coefficient (k_La) (21 and 35 h⁻¹). Experiments were conducted on a bench bioreactor (2 L volumetric capacity) at different initial k_La values (21 and 35 h⁻¹). SCHH medium was supplemented with rice bran extract (10 g L⁻¹) and yeast extract (1 g L⁻¹). Cy. xylosilytica showed high xylitol production performance (19.56 g L⁻¹), xylitol yield (0.56 g g⁻¹) and, maximum xylitol-specific production rate (μp_máx 0.20 g_xylitol·g⁻¹ h⁻¹) at k_La value of 21 h⁻¹, concomitantly slowing the rate of acetic acid consumption. A faster acetic acid consumption (100%) by Cy. xylosilytica was observed at k_La of 35 h⁻¹, concomitantly with an increase in maximum cellular growth (14.60 g L⁻¹) and reduction in maximum xylitol production (14.56 g L⁻¹ and Y_p/s 0.34 g g⁻¹). This study contributes to pioneering research regarding this yeast performance in bioreactors, emphasizing culture medium detoxification and xylitol production.

Six yeast isolates were obtained from rotting wood samples in Brazil and frass of a cerambycid beetle larva in French Guiana. Sequence analysis of the ITS-5.8S region and the D1/D2 domains of the large subunit rRNA gene showed that the isolates represent a novel species of Cyberlindnera. This novel species is related to Cyberlindnera japonica, Cyberlindnera xylosilytica, Candida easanensis and Candida maesa. It is heterothallic and produces asci with two or four hat-shaped ascospores. The name Cyberlindnera dasilvae sp. nov. is proposed to accommodate the novel species. The holotype of Cy. dasilvae is CBS 16129^T and the designated paratype is CBS 16584. The MycoBank number is 838252. All isolates of Cy. dasilvae were able to convert xylose into xylitol with maximum xylitol production within 60 and 72 h. The isolates produced xylitol with values ranging from 12.61 to 31.79 g l⁻¹ in yeast extract–peptone–xylose medium with 5% xylose. When the isolates were tested in sugarcane bagasse hydrolysate containing around 35–38 g l⁻¹ d-xylose, isolate UFMG-CM-Y519 showed maximum xylitol production.

O conceito de sala de aula invertida e o uso de tecnologias baseadas na internet vêm sendo usados em diversas áreas do conhecimento como métodos alternativos à metodologia tradicional. Este conceito engloba um método de aprendizagem ativa, no qual o aluno faz a internalização dos conteúdos essenciais antes da aula e depois discute e interage com o professor, esclarecendo as dúvidas. Diante disso, este trabalho teve como objetivo analisar a evolução dos modelos mentais de estudantes do curso técnico subsequente em mecânica de uma instituição federal brasileira, referente ao tópico de ensaios mecânicos, visando diagnosticar eventuais lacunas conceituais do desenvolvimento do conhecimento. Foi utilizada a análise quantitativa por meio de questionários, aplicados antes e após o conteúdo ministrado em sala de aula. O experimento foi realizado com amostra aleatória de n = 13 estudantes, e teve o intuito de fazer uma análise comparativa entre os participantes. De acordo com os resultados obtidos, o percentual de acerto antes e após ministrar o conteúdo foi de 33,85 % e 69,23 %, respectivamente, o que justifica que as pontuações dos alunos no questionário pós foram mais altas em relação ao questionário prévio. Este fato constata que a sala de aula invertida ou ensino híbrido pode levar a um melhor desempenho acadêmico dos estudantes. Este trabalho permitiu também detectar lacunas de aprendizagem, as quais não seriam possíveis serem identificadas por meio de avaliações tradicionais, possibilitando um aperfeiçoamento do processo de ensino e aprendizagem, com base em um planejamento didático mais eficaz.

This study aimed to screen the xylitol‐producing strains of Cyberlindnera xylosilytica and Wickerhamomyces rabaulensis for the bioconversion of the hemicellulosic fraction of sugarcane bagasse. Among the 16 strains tested, two of each species (C. xylosilytica UFMG‐CM‐Y309 and UFMG‐CM‐Y409, and W. rabaulensis UFMG‐CM‐Y3716 and UFMG‐CM‐Y3747) were selected on the basis of xylitol yield (Y_p/s) and xylitol volumetric productivity (Q_p) in YPX broth (yeast extract, 10 g L⁻¹; peptone, 20 g L⁻¹; and d‐xylose, 60 g L⁻¹). These strains were cultivated in sugarcane bagasse hemicellulosic hydrolysate (SCHH) supplemented with ammonium sulfate, rice bran extract, and yeast extract. The xylitol yield was the highest in the strain C. xylosilytica UFMG‐CM‐Y‐309 with a production of 14.06 g L⁻¹; xylitol yield, 0.63 g g⁻¹; xylitol volumetric productivity, 0.20 g L⁻¹ h⁻¹. Xylitol yields ranged from 14% to 74% above those of other xylitol‐production yeast species. This work demonstrates the potential of biotechnological application of these yeasts for xylitol production. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

O emprego de subprodutos para a produção de etanol tem se mostrado cada vez mais presente no âmbito de pesquisas uma vez que busca-se reduzir os impactos ger...