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Avaliação do uso de nano carreadores de ramnolipídeos associados ao fotossensibilizador azul de Taylor na terapia fotodinâmica antimicrobiana contra Staphylococcus aureus: estudo in vitro

2026-01-14T17:57:07Z

Título: Avaliação do uso de nano carreadores de ramnolipídeos associados ao fotossensibilizador azul de Taylor na terapia fotodinâmica antimicrobiana contra Staphylococcus aureus: estudo in vitro Autor(es): Jesus, Romário Santiago de Primeiro Orientador: Pinheiro, Antonio Luiz Barbosa Abstract: The increase in bacterial resistance to antibiotics has driven the search for alternative therapies, such as Antimicrobial Photodynamic Therapy (PDT). With the advancement of science, nanotechnology techniques are increasingly present, promoting the enhancement of existing techniques. This study evaluated, in vitro, the efficacy of PDT coupled with carrier nanotechnology against Staphylococcus aureus (ATCC 25923) in planktonic cultures, using the photosensitizer 1,9-dimethylmethylene blue (DMMB, λ ≈ 656 nm) and rhamnolipid nanocarriers (RL-NPs) produced by Pseudomonas aeruginosa. Seven experimental groups were established: Control (no treatment); LED (irradiation only, 20 J/cm²); DMMB (300 ng/mL); RL-NPs (300 ng/mL); RL-NPs/DMMB (300 ng/mL); PDT (DMMB + LED); and PDT+RL-NPs/DMMB (nanocarrier + LED). Photodynamic activation was performed with a prototype red LED (λ = 630 nm, power of 45.2 mW/cm²). Statistical analysis (one-way ANOVA with Tukey's post-hoc test) demonstrated that PDT promoted a significant reduction of ~2 logs (99.1%, p<0.0001) in bacterial viability. Notably, the group containing PDT+RL-NPs/DMMB nanotechnology showed a marked reduction of ~3 logs (99.9%, p<0.0001), significantly exceeding the standard PDT. The results indicate that the encapsulation of DMMB in rhamnolipid nanostructures enhances the antimicrobial efficacy of PDT. The characterizations performed on the nanocarrier elucidated in more detail the nature of the particles formed, including size, surface charge, and shape, which contributed to the enhanced effect, thus representing a promising strategy for the development of innovative clinical protocols against bacterial infections. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese

Prospecção e caracterização funcional de genes associados a estresse abiótico em mamona (Ricinus communis L.)

2026-01-14T17:08:06Z

Título: Prospecção e caracterização funcional de genes associados a estresse abiótico em mamona (Ricinus communis L.) Autor(es): Oliveira Júnior, Jair Lucas Primeiro Orientador: Castro, Renato Delmondez de Abstract: Castor (Ricinus communis L.) is an oilseed species of great economic and industrial importance, widely recognized for the high commercial value of the oil extracted from its seeds, which is used in the production of medicines, cosmetics, and biofuels. In Brazil, the crop holds significant socioeconomic relevance, being traditionally cultivated by smallholder farmers in the semi-arid region of the Northeast, where rudimentary agricultural systems and adverse environmental conditions prevail. In these regions, plants are frequently exposed to abiotic stresses such as drought, salinity, and high temperatures. To survive these challenges and maintain cellular homeostasis, castor bean exhibits complex defense mechanisms involving antioxidant enzymes, such as superoxide dismutase (SOD), and regulatory and protective proteins, such as heat shock transcription factors (HSFs) and heat shock proteins (HSPs). The objective of this thesis was to elucidate the molecular and biochemical mechanisms associated with castor bean adaptation to abiotic stress conditions, through the functional characterization of the RcFeSOD8 gene and the genomic analysis of the HSF, HSP70, and HSP100 gene families. In Chapter 1 (published article), the RcFeSOD8 gene was characterized, and its physiological, biochemical, and metabolic roles were investigated through overexpression in Arabidopsis thaliana. RcFeSOD8 was strongly induced under heat stress in R. communis during seed germination and seedling growth. Arabidopsis lines overexpressing RcFeSOD8 exhibited improved germination under drought, salinity, and heat conditions, accompanied by increased antioxidant enzyme activity, higher chlorophyll content, and enhanced thermotolerance. Metabolomic analysis revealed differential accumulation of key amino acids (threonine, valine, isoleucine, sarcosine, and glycine) and sucrose in transgenic lines under stress, suggesting that RcFeSOD8 participates in the modulation of carbon and nitrogen metabolism, contributing to redox homeostasis and protecting amino acid biosynthetic pathways from oxidative damage. In Chapter 2 (submitted article), 18 RcHSF genes were identified, distributed across seven chromosomes of R. communis. These genes were classified into three major classes and ten subclasses, containing cis-regulatory elements associated with abiotic stress responses (ABRE, MeJARE, GARE, and SARE). The results showed that RcHSFs respond to both high and low temperatures during seed germination and early seedling development, as demonstrated by microarray analysis at the stages of imbibition, radicle protrusion (germination per se), and post-germination (young seedlings), as well as by qPCR validation of selected genes. In particular, RcHSF08 (Class A) showed strong induction under heat stress during the early seedling stage, whereas RcHSF10 (Class C) was upregulated during the initial developmental stages under both control and stress conditions compared with dry seeds. In Chapter 3 (article 9 in preparation), 14 members of the RcHSP70 gene family and five RcHSP100 genes were identified and characterized in R. communis. Based on sequence divergence, members of these families from five plant species were systematically grouped according to their predicted subcellular localization. Genomic analyses revealed that these genes harbor regulatory elements related to growth, development, hormonal signaling, and abiotic stress tolerance. Expression profiling indicated differential expression patterns of HSP70 and HSP100 genes across tissues and under various stress conditions (drought, salinity, and heat), confirming their participation in the castor bean stress response and adaptation mechanisms. Altogether, the results of this thesis contribute to advancing the understanding of the molecular and physiological mechanisms underlying abiotic stress tolerance in R. communis and highlight the potential of genes such as RcFeSOD8 and members of the RcHSF, RcHSP70, and RcHSP100 families as promising candidates for genetic improvement programs aimed at enhancing castor bean vigor and resilience under adverse environmental conditions—ultimately supporting greater productivity, particularly for smallholder farmers in the Brazilian semi-arid region. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese

Otimizações operacionais do cultivo de microalgas em água produzida da indústria do petróleo visando o seu tratamento e reuso em um processo de produção de bioativos

2025-04-23T18:19:47Z

Título: Otimizações operacionais do cultivo de microalgas em água produzida da indústria do petróleo visando o seu tratamento e reuso em um processo de produção de bioativos Autor(es): Silva, Carine Souza da Primeiro Orientador: Chinalia, Fabio Alexandre Abstract: Produced water (PW) from the oil industry represents a significant environmental challenge due to its high salinity and complex chemical composition. Sustainable treatment of this effluent is essential to reduce environmental impacts and enable its reuse. Microalgae, such as Dunaliella salina, stand out as a biotechnological alternative for PW remediation, while also allowing the production of high-value biocompounds such as lipids and pigments. This study evaluated the effects of alternating electric current and different light spectra on the growth, biomass production, and accumulation of lipids and pigments in D. salina cultivated in PW and synthetic medium. Different electric current intensities (50, 750, and 990 µA) and frequencies (1, 50, and 100 Hz), as well as LED lighting with different wavelengths (red, blue, pink, and white) at a light intensity of 3,800 lux, were tested. The results showed that applying 50 µA at a frequency of 1 Hz, once a day for 30 minutes, in Conway medium with 8.5% salt salinity, promoted a 92% increase in specific growth rate. The highest biomass accumulation (70%) was observed in Conway with 3.5% salts, under electric stimulation of 50 µA at 1 Hz, once a day for 30 minutes. The intermittent treatment (5 minutes on and 5 minutes off), using 750 µA of alternating current at 1 Hz in Conway 3.5% salts, resulted in a 104% increase in lipid production. PW also showed positive effects under electrical stimulation. At 8.5% salinity, biomass production increased by 23% when applying 990 µA twice a day for 30 minutes. Meanwhile, an intensity of 50 µA applied once a day for 30 minutes led to a 66% lipid accumulation. Light stimulation also had positive impacts on D. salina: under red LED light, there was a 62% and 34% increase in specific growth rate and biomass production, respectively, and blue LED light stimulated lipid production by approximately 205%. These findings highlight the potential of combining electrical and light stimuli to optimize D. salina cultivation, contributing to sustainable bioprocesses and enhancing the feasibility of using PW as a culture medium in biotechnological applications. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese

Caracterização genômica e biotecnologica das microalgas Chlamydomonas biconvexa e Dunaliella viridis

2024-10-04T19:27:32Z

Título: Caracterização genômica e biotecnologica das microalgas Chlamydomonas biconvexa e Dunaliella viridis Autor(es): Pascoal, Patrícia Verdugo Primeiro Orientador: Brasil, Bruno dos Santos Alves Figueiredo Abstract: Microalgae have the potential to produce a variety of active ingredients of industrial interest, whether in the food industry, due to the high protein and carbohydrate content of their biomass; or in the treatment of agro-industrial effluents, such as POME (Palm oil mil effluent). It can also be used in the industry to produce assets with high added value, such as carotenoid pigments, which are used in cosmetics, animal nutrition, and human food. Among the species with biotechnological potential, two strains isolated from Brazilian environments stand out: the freshwater Chlamydomonas biconvexa Embrapa|LBA40 and the halotolerant species Dunaliella viridis Embrapa|LBAS001. This study showed that the strain C. biconvexa Embrapa|LBA40, isolated and cultivated in palm oil industry effluent (POME), was able to achieve biomass productivity of 190.60 mg DW • L-1 • d-1 in 15L flat plate airlift photobioreactors. The species was able to reduce ammonia and nitrite from the POME residue by 99%, as well as reducing phosphate by 98% after 5 days of cultivation. In addition, the mitochondrial genome was obtained through genetic sequencing, revealing an mtDNA of 15.98 Kb, with 14 genes, 9 of which are protein-coding genes. Phylogenetic analysis using the COX1 gene confirmed the taxonomic identification as C. biconvexa, opening opportunities for future genetic studies to modify and improve the species. The microalgae strain Dunaliella viridis EMBRAPA| LBA#S001, isolated from saline lagoons in Brazil, was studied for its morphological and genomic characteristics. The strain was identified by molecular markers, such as the rbcL and ITS2 genes, and demonstrated high tolerance to high salinities, with consistent growth in NaCl concentrations of up to 4.8 M. The production of β-carotene was evaluated, resulting in 18.7 mg/L, comparable to the levels found in other species of the genus. The mitochondrial DNA revealed a genome of 46.2 Kbp, while the chloroplast genome reached 197.1 Kb, both with genes essential for photosynthesis. The analysis of the nuclear genome, with 176.9 Mb, identified 29,594 protein-coding genes, indicating a significant potential for biotechnology. The study analyzed the resistance genes in the strain, identifying mechanisms such as antibiotic target switching and antibiotic efflux. The presence of genes such as vanY and adeF suggests adaptive diversity in contaminated environments. Analysis of transcription factors highlights the regulation of genes essential for photosynthesis and stress responses. Manipulating these factors could increase the production of valuable compounds such as carotenoids. The development of synthetic promoters is crucial to optimizing microalgae as biotechnological platforms, compared to more traditional organisms. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese