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Aspectos do metabolismo de manose em Saccharomyces cerevisiae e produção de etanol a partir da semente de açaí

Fri, 24 Oct 2025 00:00:00 GMT

Title: Aspectos do metabolismo de manose em Saccharomyces cerevisiae e produção de etanol a partir da semente de açaí Author(s)/Inventor(s): Brand, Mayla Ramos Duarte Advisor: Silva, Ayla Sant’Ana da Abstract: The açaí seed represents about 85% of the fruit’s total mass, generating approximately 1.6 million tons of waste annually, most of which is improperly discarded, causing environmental and sanitary problems. Since around 50% of the seed is composed of mannan, an alternative use is its conversion into mannose followed by fermentation to ethanol. This study aimed to understand the metabolic aspects involved in mannose fermentation and to evaluate ethanol production parameters using hydrolysate from açaí seeds. Metabolic aspects were analyzed in four Saccharomyces cerevisiae laboratory strains with deletions in the genes encoding the enzymes Hxk1, Hxk2, and Glk1, responsible for converting mannose into mannose-6-phosphate, allowing only one enzyme to be expressed per strain. One strain, lacking all three enzymes, was referred to as the triple-deletion strain. All strains grew on mannose in solid medium except for the triple-deletion strain. In liquid medium with 2% sugars, the presence of at least one enzyme was sufficient for mannose consumption and ethanol production, whereas the triple-deletion strain showed no mannose metabolism or ethanol formation. Hxk1 and Hxk2 were more relevant for catabolite repression, showing ethanol production efficiencies of 96.81% and 99.07% (after 6 h), while Glk1 reached 26.54%. Additionally, 13 brewing strains and two industrial fuel-ethanol-producing strains (CAT-1 and Ethanol Red) were evaluated to identify those with higher fermentative potential. Qualitative assays in solid medium showed similar growth in mannose and glucose, and a liquid medium assay with 5% sugars and 1 g/L inoculum led to the selection of CAT-1, ART06, and ART48. Considering the importance of catabolite repression, the repressive effect of mannose was assessed, showing that after 4 h, mannose had a similar effect to glucose in all strains. To study ethanol production, sugar and inoculum concentrations were evaluated. Fermentations with 50 g/L sugars (91% mannose, 9% glucose) and 10 g/L inoculum resulted in sugar consumption of 91.06% (CAT-1), 93.87% (ART06), and 87.49% (ART48), with ethanol production efficiencies of 84.01%, 92.68%, and 96.10%, respectively. Fermentations with 100 g/L sugars reduced efficiencies to 72.11% (CAT-1), 76.75% (ART06), and 72.98% (ART48). Finally, the enzymatic hydrolysate of açaí seed supplemented with nutrients (100 g/L sugars and 10 g/L inoculum) resulted in efficiencies of 84.89% (CAT-1), 81.32% (ART06), and 90.83% (ART48). The study demonstrated that CAT-1, ART06, and ART48 have strong potential for mannose fermentation from açaí seeds, with efficiencies above 85%. The presence of at least one of the enzymes Hxk1, Hxk2, or Glk1 is sufficient for mannose metabolism, with Hxk1 and Hxk2 being crucial for catabolite repression, confirming the technical feasibility of using this agro-industrial residue for second-generation ethanol production. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação

Perfis proteômico e genômico associados à severidade da COVID-19 em uma coorte de pacientes do Rio de Janeiro

Tue, 24 Mar 2026 00:00:00 GMT

Title: Perfis proteômico e genômico associados à severidade da COVID-19 em uma coorte de pacientes do Rio de Janeiro Author(s)/Inventor(s): Ferreira, Sâmila Natiane Advisor: Barboza, Luciana Pizzatti Abstract: COVID-19 is an infectious disease caused by SARS-CoV-2 and was characterized as one of the major global public health emergencies between March 2020 and May 2023. Although most infected individuals develop mild to moderate respiratory symptoms, a subset progresses to severe disease, often associated with inflammatory and thrombotic dysfunctions and adverse clinical outcomes. Even after the expansion of vaccination coverage and the reduction in severe cases, SARS-CoV-2 still accounts for a significant proportion of viral Acute Respiratory Distress Syndrome (ARDS) cases in Brazil. In this context, the present study aimed to investigate proteomic and genomic signatures associated with COVID-19 severity, seeking to identify biomarkers and molecular pathways potentially involved in the disease pathophysiology. The study included patients aged ≥18 years with COVID-19 confirmed by RT-PCR, recruited from HNMD and NEEDIER-UFRJ. An integrative approach was employed using different molecular biology techniques, including oxidative stress assessment, proteomics, and genomic association analysis, taking into account the patients’ clinical status and outcomes. The results demonstrated a significant increase in lipid peroxidation in patients with elevated D-dimer levels and in those who required mechanical ventilation, indicating higher oxidative stress in these groups. Proteomic analysis, performed on pooled samples stratified by D-dimer levels (≥2000 μg/L and <2000 μg/L), identified 12 differentially expressed proteins, highlighting the upregulation of proteins associated with coagulation (ATRN, ITIH4, APOB, C5, SERPINA1, PPBP, and PROS1) and the downregulation of proteins related to the immune response (C4A, IGHG1, IGHG3, MYH9, and B2M). Functional enrichment analyses supported these findings, showing that downregulated biological processes and signaling pathways were mainly associated with immune response, whereas upregulated processes and pathways were primarily involved in inflammation, coagulation, and chemotaxis— a pattern consistent with the thromboinflammation described in severe COVID-19. Complementarily, genomic association analysis comparing patients with severe (cases) and mild (controls) disease identified polymorphisms in the EML1 gene (rs11628837, rs8020741, and rs4900448) associated with a protective effect (OR = 0.3648; 95% CI: 0.2418–0.5503; p = 1.528 × 10⁻⁶). Overall, these results allowed the characterization of a molecular profile associated with severe COVID-19, confirmed the role of D-dimer as a robust prognostic marker, and suggested novel molecular biomarkers and biological pathways with potential for therapeutic intervention. Publisher: Universidade Federal do Rio de Janeiro Type: Tese

Produção biológica de hidrogênio e metano a partir de vinhaça e torta de filtro da cana-de-açúcar

Wed, 29 Apr 2026 00:00:00 GMT

Title: Produção biológica de hidrogênio e metano a partir de vinhaça e torta de filtro da cana-de-açúcar Author(s)/Inventor(s): Haguihara, Gabriel Gomes Advisor: Ferreira-Leitão, Viridiana Santana Abstract: The Brazilian economy is strongly based in the agro-industrial sector, with sugarcane occupying a prominent position on the global stage. In this industry, substantial volumes of effluents and residues are generated, notably vinasse and filter cake, which are predominantly applied via fertigation, a practice associated with potential environmental risks. Anaerobic codigestion (CoAD) of these residues emerges as a promising alternative: filter cake can supply essential nutrients to vinasse, thereby adding value while enabling the generation of clean and renewable energy. In this study, biological hydrogen (H₂) and methane (CH₄) production were evaluated under both single-stage and sequential mode using vinasse and filter cake as substrates. During the H2 production phase, the effects of the organic matter-to-inoculum ratio (COD:VSS), thermal pretreatment of the inoculum, and vinasse supplementation were investigated. H2 production was found to be directly proportional to the COD:VSS ratio, with a ratio of 3:1 yielding a productivity (Qp) 173% higher than that obtained at 1:1. The use of untreated sludge outperformed inoculum pre-treated at 65 °C for 30 minutes, achieving an 80% higher yield. Preliminary assessment of vinasse supplementation indicated a 24-hour reduction in the lag phase. Based on these findings, co-fermentation of vinasse and filter cake was conducted to replace exogenous supplementation and explore potential synergistic effects. The adopted strategy involved evaluating different substrate proportions (Vx/Ty), where “x” and “y” represent the percentage contribution of COD from vinasse (V) and filter cake (T), respectively. The V50/T50 condition, conducted at 50 °C using untreated sludge, exhibited the best performance. Compared to vinasse mono-fermentation, this condition increased Qp by 362% (reaching 707 N-mL H₂·L⁻¹·d⁻¹) and reduced the lag phase by 80% (from 72 to 14 hours), achieving a maximum cumulative hydrogen production of 894 N-mL·L⁻¹ within 5 days. Furthermore, the process was successfully scaled up to stirred-tank reactors of 1.5 L and 7.27 L, yielding 687.3 ± 10 N-mL·L⁻¹ of H₂ within 2 days, while maintaining both Qp and lag phase duration, thus demonstrating high reproducibility (p > 0.05). In direct methanogenesis at 35 °C, lower COD:VSS ratios were more favorable: the 1:1 ratio achieved a higher yield (278 mL CH₄ per gram of COD consumed, gCODc) and an 80% shorter lag phase compared to the 3:1 ratio (172 mL CH₄/gCODc). When comparing methanogenic processes, sequential digestion of the effluent (EPH V50/T50) at 35 °C outperformed single-stage digestion. Relative to CoAD of the same mixture (V50/T50), which reached 226 mL CH₄/gCODc, the two-stage configuration increased the yield to 347 mL CH₄/gCODc. The sequential pathway also ensured highly efficient organic matter degradation, achieving an 80% COD removal and surpassing single-stage CoAD (70.3%). These results demonstrate that sequential production not only enables energy recovery from the fermentative phase but also maximizes methane conversion. It is concluded that the integrated valorization of these residues enhances overall energy recovery and supports the transition of the sugar-energy sector toward a sustainable, zero-waste biorefinery model. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação

Estudos de fitorremediação de solo contaminado com chumbo por Helianthus annuus L. (Girassol): análise fisiológica, bioquímica e proteômica

Wed, 01 Jan 2025 00:00:00 GMT

Title: Estudos de fitorremediação de solo contaminado com chumbo por Helianthus annuus L. (Girassol): análise fisiológica, bioquímica e proteômica Author(s)/Inventor(s): Santos Junior, Elizeu Rosa dos Advisor: Silva, Márcia Regina Soares da Abstract: Environmental contamination by heavy metals represents one of the greatest ecological challenges of the present time due to the persistence of these elements and their toxicity to living organisms. Phytoremediation emerges as a sustainable alternative for soil decontamination, exploiting the potential of plant species capable of absorbing, stabilizing, or degrading pollutants. The present study aimed to evaluate the remediation potential of soils contaminated with lead [Pb(NO₃)₂] using two Brazilian sunflower cultivars, BRS 323 and BRS 415. Plants were cultivated for 30 days in soils containing different Pb(NO₃)₂ concentrations: 0, 150, and 900 mg kg⁻¹, corresponding to the alert and intervention levels established by CETESB and CONAMA. Samples of roots, stems, and leaves were collected and subjected to physicochemical, morphological, enzymatic, and proteomic analyses. Physiological results demonstrated that both cultivars exhibited high germination viability; however, BRS 323 showed greater tolerance to lead, maintaining higher germination and growth rates. Lead accumulation was predominantly concentrated in the roots, indicating a phytostabilization mechanism. Morphological development showed alterations in leaf and root structures and a reduction in overall growth, although the 900 mg kg⁻¹ treatment (PB900) displayed superior performance compared to 150 mg kg⁻¹ (PB150), suggesting a non-linear adaptive response. Regarding photosynthetic pigments, a slight reduction in chlorophyll content was observed under contamination, while carotenoid levels remained stable, indicating possible resilience of the photosynthetic apparatus. Biochemical analyses revealed elevated ATP content, reflecting increased energy demand to sustain defense processes. Although hydrogen peroxide (H₂O₂) levels increased, this effect was counterbalanced by the activation of antioxidant enzymes, particularly catalase and ascorbate oxidase. Proteomic analysis identified 1,691 proteins associated with detoxification pathways, ion homeostasis, energy metabolism, and protein repair. The study demonstrated that sunflower possesses a complex molecular machinery capable of reorganizing its metabolism under lead-induced stress, involving ion sequestration responses, redox adjustments, and proteomic reprogramming. The superior performance of the BRS 323 cultivar under high contamination conditions suggests the presence of efficient resistance mechanisms and potential use in sustainable remediation strategies. Based on these findings, we conclude that cultivar BRS 323 exhibits a high phytoremediation potential for lead-contaminated soils, combining physiological tolerance, root sequestration capacity, and adaptive proteomic reprogramming. Publisher: Universidade Federal do Rio de Janeiro Type: Tese