Repositório Colecção: Artigos em Revistas InternacionaisArtigos em Revistas Internacionaishttps://hdl.handle.net/1822/192024-03-28T14:26:18Z2024-03-28T14:26:18ZHydrocarbon toxicity towards hydrogenotrophic methanogens in oily waste streamsMorais, Bruno P.Martins, ValdoMartins, GilbertoCastro, A. RitaAlves, M. M.Pereira, M. A.Cavaleiro, Ana Júlia Vianahttps://hdl.handle.net/1822/902142024-03-28T10:15:25Z2024-03-27T22:24:16ZTítulo: Hydrocarbon toxicity towards hydrogenotrophic methanogens in oily waste streams
Autor: Morais, Bruno P.; Martins, Valdo; Martins, Gilberto; Castro, A. Rita; Alves, M. M.; Pereira, M. A.; Cavaleiro, Ana Júlia Viana
Resumo: Hydrocarbon-containing wastes and wastewaters are produced worldwide by the activities of the oil and gas industry. Anaerobic digestion has the potential to treat these waste streams, while recovering part of its energy potential as biogas. However, hydrocarbons are toxic compounds that may inhibit the microbial processes, and particularly the methanogens. In this work, the toxicity of hexadecane (0–30 mM) towards pure cultures of hydrogenotrophic methanogens (Methanobacterium formicicum and Methanospirillum hungatei) was assessed. Significantly lower (p < 0.05) methane production rates were only verified in the incubations with more than 15 mM hexadecane and represented up to 52% and 27% inhibition for M. formicicum and M. hungatei, respectively. The results obtained point out that 50% inhibition of the methanogenic activity would likely occur at hexadecane concentrations between 5–15 mM and >30 mM for M. formicicum and M. hungatei, respectively, suggesting that toxic effects from aliphatic hydrocarbons towards hydrogenotrophic methanogens may not occur during anaerobic treatment. Hydrocarbon toxicity towards hydrogenotrophic methanogens was further assessed by incubating an anaerobic sludge with H2/CO2 in the presence of a complex mixture of hydrocarbons (provided by the addition of an oily sludge from a groundwater treatment system). Specific methanogenic activity from H2/CO2 decreased 1.2 times in the presence of the hydrocarbons, but a relatively high methane production (~30 mM) was still obtained in the assays containing the inoculum and the oily sludge (without H2/CO2), reinforcing the potential of anaerobic treatment systems for methane production from oily waste/wastewater.
<b>Tipo</b>: article2024-03-27T22:24:16ZFrom crude glycerol and volatile fatty acids to biodiesel and other bioproducts using Yarrowia lipolytica NCYC 2904 as a cell factoryPereira, Ana SofiaLopes, MarleneBelo, Isabelhttps://hdl.handle.net/1822/902012024-03-28T13:30:22Z2024-03-27T17:50:47ZTítulo: From crude glycerol and volatile fatty acids to biodiesel and other bioproducts using Yarrowia lipolytica NCYC 2904 as a cell factory
Autor: Pereira, Ana Sofia; Lopes, Marlene; Belo, Isabel
Resumo: Biodiesel production using microbial lipids derived from low-cost feedstocks could provide a sustainable alternative for the replacement of conventional fossil fuels. This work studied fed-batch and two-stage batch cultures for microbial lipids production by oleaginous yeast Yarrowia lipolytica NCYC 2904 from crude glycerol (a by-product of the biodiesel industry) and volatile fatty acids (obtained during the anaerobic fermentation of organic wastes). Fed-batch at a constant feeding rate of the medium with 100 g L1 of glycerol and an initial dilution rate of 0.004 h1, followed by the pulse addition of an 18 g L1 VFAs mixture at the end of the fed-batch phase was the best strategy to obtain the highest intracellular lipids accumulation per dry cell mass of 38% (w/w). Microbial lipids produced by Y. lipolytica NCYC 2904 (90% of unsaturated fatty acids) were successfully converted into biodiesel, whose main properties are within the international biodiesel standards EN 14214 and are similar to those of biodiesel produced from vegetable oils. Furthermore, a high amount of citric acid (28 g L1) and total polyols (mannitol and arabitol) of 3 g L1 was produced during this bioprocess, which makes it even more interesting within an integrated biorefinery framework.
<b>Tipo</b>: article2024-03-27T17:50:47ZDeep eutectic solvents as suitable solvents for lipase-catalyzed transesterification reactionsNoro, Jennifer MartinsCabo, JoanaFreitas, David S.Roque, Catarina S.de Castro, MarianaCavaco-Paulo, ArturSilva, C.https://hdl.handle.net/1822/899532024-03-25T20:59:41Z2024-03-25T12:28:24ZTítulo: Deep eutectic solvents as suitable solvents for lipase-catalyzed transesterification reactions
Autor: Noro, Jennifer Martins; Cabo, Joana; Freitas, David S.; Roque, Catarina S.; de Castro, Mariana; Cavaco-Paulo, Artur; Silva, C.
Resumo: In this work, three deep eutectic mixtures (DES 1: choline chloride/urea; DES 2: choline chloride/glycerol; and DES 3: tetrabutylammonium bromide/imidazole) were investigated as mediums for the synthesis of glucose laurate and glucose acetate. Aiming to achieve a greener and more sustainable approach, the synthesis reactions were catalyzed by lipases from Aspergillus oryzae (LAO), Candida rugosa (LCR), and porcine pancreas (LPP). The hydrolytic activity of lipases against p-nitrophenyl hexanoate revealed no evidence of enzyme inactivation when DES were used as medium. Regarding the transesterification reactions, combining LAO or LCR with DES 3 resulted in the efficient production of glucose laurate (from glucose and vinyl laurate) (conversion >60 %). The best result for LPP was observed in DES 2, with 98 % of product production after 24 hours of reaction. When replacing vinyl laurate by a smaller hydrophilic substrate, vinyl acetate, a distinct behavior was observed. LCR and LPP performed better in DES 1, yielding more than 80 % of glucose acetate after 48 hours of reaction. The catalytic activity of LAO was less pronounced, reaching only nearly 40 % of product in DES 3. The results highlight the potential of combining biocatalysis with greener and environmentally-safer solvents, for the synthesis of differentiated chain-length sugar fatty acid esters (SFAE).
<b>Tipo</b>: article2024-03-25T12:28:24ZPolymeric biomaterials for wound healingOliveira, CristianaSousa, DianaTeixeira, J. A.Santos, Pedro Miguel FerreiraBotelho, C. M.https://hdl.handle.net/1822/899072024-03-23T21:01:05Z2024-03-23T12:26:32ZTítulo: Polymeric biomaterials for wound healing
Autor: Oliveira, Cristiana; Sousa, Diana; Teixeira, J. A.; Santos, Pedro Miguel Ferreira; Botelho, C. M.
Resumo: Skin indicates a person’s state of health and is so important that it influences a person’s emotional and psychological behavior. In this context, the effective treatment of wounds is a major concern, since several conventional wound healing materials have not been able to provide adequate healing, often leading to scar formation. Hence, the development of innovative biomaterials for wound healing is essential. Natural and synthetic polymers are used extensively for wound dressings and scaffold production. Both natural and synthetic polymers have beneficial properties and limitations, so they are often used in combination to overcome overcome their individual limitations. The use of different polymers in the production of biomaterials has proven to be a promising alternative for the treatment of wounds, as their capacity to accelerate the healing process has been demonstrated in many studies. Thus, this work focuses on describing several currently commercially available solutions used for the management of skin wounds, such as polymeric biomaterials for skin substitutes. New directions, strategies, and innovative technologies for the design of polymeric biomaterials are also addressed, providing solutions for deep burns, personalized care and faster healing.
<b>Tipo</b>: article2024-03-23T12:26:32ZAssessment of the gastrointestinal fate of bacterial nanocellulose and its toxicological effects after repeated-dose oral administrationRodrigues, Ana Cristina CostaCosta, Liliana Marisa BarrosSilva-Carvalho, RicardoMota, RenatoDuarte-Silva, SaraCastro, Andreia Cristiana TeixeiraLamas, Nuno JorgeOliveira, Gonçalo N. P.Wan, YizaoDourado, FernandoGama, F. M.https://hdl.handle.net/1822/898272024-03-22T10:09:11ZTítulo: Assessment of the gastrointestinal fate of bacterial nanocellulose and its toxicological effects after repeated-dose oral administration
Autor: Rodrigues, Ana Cristina Costa; Costa, Liliana Marisa Barros; Silva-Carvalho, Ricardo; Mota, Renato; Duarte-Silva, Sara; Castro, Andreia Cristiana Teixeira; Lamas, Nuno Jorge; Oliveira, Gonçalo N. P.; Wan, Yizao; Dourado, Fernando; Gama, F. M.
Resumo: Bacterial nanocellulose (BNC), a nanofibrillar polysaccharide produced by certain acetic acid bacteria, may be used in food, pharma and many other applications. As with other nanoscale celluloses, the oral toxicology of BNC is still controversial. Therefore, we aimed to assess whether BNC is absorbed at the intestine following administration in Wistar rats. This is, to our knowledge, the first attempt to track in vivo the potential internalization of (nano)cellulose fibers. For 21 days, animals were subjected to daily oral gavage of an aqueous suspension 1% (w/v) BNC or of its counterpart of plant origin (Avicel LM310). During the assay, clinical observations, such as body weight measurements, food consumption and ophthalmologic evaluations were performed. After occision, serum chemistry, necropsy examination and histopathological analyses of the liver, kidneys, spleen and small and large intestines were performed. The presence of BNC fibers along the gastrointestinal tract was assessed histologically using a green fluorescence protein coupled to a cellulose carbohydrate binding module (GFP-CBM). No evidence of BNC persorption was found. Particularly, no BNC was detected in the Peyer's patches or in the mesenteric lymphatic nodules. Moreover, the histopathological analyses revealed that the global architecture and morphology of the organs and tissues were preserved, with no significant pathological changes being observed. Regarding serum biochemistry, no significant differences were recorded. These findings suggest that BC nanofibers are not absorbed at the intestine and can be considered a safe food additive.
<b>Tipo</b>: article