UB - Comunicações em actas de encontros científicos internacionais
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Browsing UB - Comunicações em actas de encontros científicos internacionais by Author "Alves, Luís"
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- Application of ionic liquids for bacterial carotenoid extractionPublication . Salgado, Francisco; Silva, Tiago; Alves, Luís; Roseiro, J. Carlos; Lukasik, Rafal M.; Paixão, Susana M.ABSTRACT: One of the ways to make microbial bioprocesses more economically viable is to enhance valorization of high added value products resulting from the biomass, like carotenoids, which have a high market value. To recover these pigments from microbial biomass a good extraction method is required. Solvent extraction is one of the methods commonly used to extract carotenoids, however, solvent extractions are both material and time-consuming, and moreover also present some health and safety concerns. Ionic liquids (ILs) are a promising step forward to tackle some of these problems, even with their high price, and has been tested for the extraction of microorganism’s components. These “molten salts” are a group of compounds that have been known for a long time, but only in the last decades they have been attracting more attention from both researchers and industry. ILs are solvents that have a high solvation power for a wide range of molecules. ILs are salts with a melting point below 100ºC, which possess unique properties that depend on both the cation and anion present, high thermal and chemical stability, a large electrochemical window, great solvent power, non-flammability, and a negligible vapor pressure. Their versatility is one of their most attractive features, making them adaptable to many technologies. Therefore, ILs can be used to facilitate chemical reactions, extraction and separation, biotransformation, and can be used in biorefineries and other processes. As shown in previous works, Gordonia alkanivorans strain 1B has the capacity to produce carotenoids, however, since it was originally isolated form hydrocarbon rich environments, it is highly resistant to different organic solvents commonly used in extraction protocols. This makes the process slow and laborious, lowering yields and increasing solvent spending. As such, new extraction protocols must be developed and tested to obtain higher pigments yield. So, herein, the potential of ILs for carotenoids extraction was evaluated, since these compounds have been described as a good option to extract pigments produced by microorganisms.
- Biodesulfurization biorefinery using Gordonia alkanivorans strain 1B: life cycle inventory of the integrated processPublication . Silva, Tiago; Silva, Carla; Paixão, Susana M.; Alves, LuísABSTRACT: High sulfur concentrations are a problem common to fossil fuels and derivatives (such as oil and coal), as well as many new generation fuels and biofuels (such as pyrolysis oils, syngas, biogas or even biodiesel). If the sulfur present in these fuels is released into the atmosphere it can result in SO2/SOx emissions, leading to environmental damage, and health issues. Transportation fuels have sulfur limits that go below 5000 ppm in ships, 3000 ppm in airplanes and 10 ppm in cars, and without treatment fuels can have several thousand ppm of sulfur. As such, they must be submitted to desulfurization, typically through a thermochemical process known as hydrodesulfurization, in which H2 is combined with the fuel at high temperatures and pressures, in the presence of metal catalysts. However, this process has significant environmental impacts. Usually, it depends on hydrogen and heat/steam produced from natural gas, totalizing 4.17 kg natural gas per 2.89 kg sulfur removed. It also involves high electricity and water consumption (approximately 2.9 kWh and 86.9 kg, respectively, per 2.89 kg sulfur removed). Furthermore, these impacts are greater for lower sulfur demands (Burgess & Brennan, 2001). Thus, there has been a search for alternative/complementary processes, one of which is biodesulfurization (BDS). It consists of the use of microorganism that consume the sulfur present in the fuels, at ambient temperature and pressure, without the need for metal catalysts. BDS still presents several bottlenecks, common to many microbial processes, such as low conversion rates and high production costs for the microbial biocatalyst. To surpass these limitations researchers have pursued different strategies: minimization/optimization of culture medium and culture conditions; employment of cheaper alternative nutrient sources; exploitation of added value products. Gordonia alkanivorans strain 1B is a bacterium known for its biodesulfurization properties. It has demonstrated several characteristics which make it interesting: it can perform BDS of different compounds, several of which extremely recalcitrant for the thermochemical process; it has very low nutritional needs; it can be cultivated on several alternative carbon sources; it has been shown to produce two different types of added value products: carotenoids and biosurfactants (Alves et al., 2015; Silva et al., 2020, 2022). Therefore, G. alkanivorans strain 1B is the ideal candidate for a biodesulfurization biorefinery, that simultaneously removes sulfur from fuels and produces carotenoids and biosurfactants.
- Biological upgrading of wastes from the pulp and paper industryPublication . Marques, Susana; Alves, Luís; Gírio, Francisco; Santos, J. A. L.; Roseiro, J. CarlosA process for biological upgrading of recycled paper sludge (RPS) was developed based on the enzymatic hydrolysis of major sludge components (cellulose and xylan) with commercial enzymes and fermentation of the resulting sugars into ethanol or lactic acid with adequate microbial strains. The process was implemented performing both steps sequentially (SHF) or simultaneously (SSF). Cellulosic and hemicellulosic fractions of RPS were completely converted by enzymatic hydrolysis (using Celluclast®1.5L with Novozym®188) into the constitutive glucose and xylose. Ethanol was produced from the RPS hydrolysate by the yeast Pichia stipitis CBS 5773. A slightly higher conversion yield was attained on SHF process, corresponding to an ethanol concentration of 19.6 g L-1, but 179 hours were needed. The SSF process was completed after 48 hours of incubation allowing the production of 18.6 g L-1 of ethanol from 178.6 g L-1 of dried RPS, corresponding to an overall conversion yield of 51% of the available carbohydrates on the initial substrate. Maximum production of lactic acid (LA) with Lactobacillus rhamnosus ATCC 7469 was obtained by performing the SSF process: 73 g L-1 of LA was achieved, corresponding to a maximum productivity of 2.9 g L-1 h-1, with 0.97 g LA produced per g of carbohydrates on initial sludge. The present results demonstrate the feasibility of the biological conversion of the ultimate waste obtained in the paper recycling loop into a biofuel (bioethanol) or an important chemical intermediate (LA, precursor of bioplastics), under the concept of a multi-purpose biorefinery.
- Energetic and environmental evaluation of microalgae biomass fermentation for biohydrogen productionPublication . Ferreira, Ana F.; Ortigueira, Joana; Alves, Luís; Gouveia, Luisa; Moura, Patrícia; Silva, Carla M.This paper presents an energetic and environmental evaluation of the fermentative hydrogen production from the sugars of Scenedesmus obliquus biomass hydrolysate by Clostridium butyricum. The main purpose of this work was to evaluate the potential of H2 production and respective energy consumptions and CO2 emissions in the global fermentation process: hydrolysis of S. obliquus biomass, preparation of the fermentation medium, degasification and incubation. The scale-up to industrial production was not envisaged. Energy consumption and CO2 emissions estimations were based on SimaPro 7.1 software for the preparation of the fermentation medium and the use of degasification gas, nitrogen. The functional unit of energy consumption and CO2 emissions was defined as MJ and grams per 1 MJ of H2 produced, respectively. The electricity consumed in all hydrogen processes was assumed to be generated from the Portuguese electricity production mix. The hydrogen yield obtained in this work was 2.9 ± 0.3 mol H2/mol sugars in S. obliquus hydrolysate. Results show that this process of biological production of hydrogen consumed 281-405 MJ/MJH2 of energy and emitted 24-29 kgCO2/ MJH2. The fermentation stages with the highest values of energy consumption and CO2 emissions were identified for future energetic and environmental process optimisation.
- Exploring Scenedesmus obliquus and nannochloropsis sp. potential as a sustianable raw material for biofuels amd high added value compoundsPublication . Gouveia, Luisa; Batista, Ana Paula; Nobre, B. P.; Marques, Paula; Moura, Patrícia; Alves, Luís; Passarinho, Paula; Oliveira, Ana Cristina; Villalobos, Fidel; Barragan, Blanca E; Palavra, António F.In this work, the authors propose a microalga-based integrated system, where optimization of several energy vectors (biodiesel, bioethanol and bioH2) is highlighted under the concept of biorefinery (Project PTDC/AAC-AMB/100354/2008). This involves the integration of different processes such as oil and sugar extraction from microalgae for biodiesel and bioethanol production respectively, and bioH2 production from the whole and/or biomass leftovers. The extraction of high value added compounds, such as carotenoids, contributes to the economic viability of the overall process.
- A fast and effective analytical method to quantify the emulsifying activity: design and validationPublication . Alves, Luís; Tavares, João; Silva, Tiago; Paixão, Susana M.ABSTRACT: Biosurfactants (BS) and bioemulsifiers (BE) are amphiphilic molecules that are produced by a wide range of microorganisms. According to Willumsen and Karlson, BS/BE are both surface active biomolecules, but while the surfactants play the role of surface tension reduction, emulsifiers are involved in formation and stabilization of emulsions. However, some biomolecules possess both surfactant and emulsifying properties, which contributes to their unique features, including high biodegradability, low toxicity, effectiveness at extremes of temperature, pH and salinity, and special biological activities (e.g., antimicrobial, antiviral, anticancer, etc). These attributes make them an alternative to their chemical counterparts and allows them to have key roles in several fields. In fact, the chemical composition of BS and BE is different, and this may contribute to their specific roles in nature and biotechnological applications; however, both BS/BE have recognized emulsifying properties, which are the focus of this study. The idea of quantifying the emulsifying activity rather than quantifying the emulsifiers and/or surfactants themselves has been studied before. The concept that stands out is the emulsification index (E24: % emulsification after 24 h) proposed by Cooper and Goldenberg [4], which is still applied, and some of its adaptations such as the one proposed by Trebbau de Acevedo and McInerney. These authors have defined one unit of emulsifying activity as the amount of emulsifier that results in an emulsification (E24) of 20%. Although theoretically simple, these approaches require considerable sample volume, have a long wait (24 h) and are lengthy. Moreover, they can be subjective, since two substances might induce complete emulsion at 24 h, with one resulting in a much denser emulsion. This may indicate more BS/BE activity; however, it is not easily comparable, or demonstratable. Furthermore, due to nature of emulsions and the factors that influence them, small differences in test conditions, such as shape or size of the tubes, or nature of the hydrophobic layer, can generate drastic differences, which hinders reproducibility between authors.
- Flow cytometric method for cell viability evaluation of Gordonia alkanivorans strain 1B in fossil fuels biodesulfurization processesPublication . Teixeira, A. V.; Silva, Tiago; Silva, Teresa Lopes da; Paixão, Susana M.; Alves, LuísThis work reports the development of a rapid flow cytometric method for the viability assessment of Gordonia alkanivorans strain 1B, a bacterium used in the biodesulfurization process. To demonstrate that it is possible to monitor by flow cytometric analysis changes in this bacterium physiological state, positive controls using the 5(6)-carboxyfluorescein diacetate (CFDA) and propidium iodide (PI) staining mixture were set. The loss of viability of G. alkanivorans resting cells in the presence of different concentrations of 2-hydroxybiphenyl, a very toxic end product of the dibenzotiophene desulfurization process, was assessed over a period of time. The results here reported demonstrate the potential of this technique for the biodesulfurization process monitoring and consequent enhancement.
- A novel microbial biosurfactant/bioemulsifier: production and characterizationPublication . Silva, Tiago; Paixão, Susana M.; Tavares, João; Alves, LuísABSTRACT: Currently there is an immediate need for new and more sustainable production methods in most industries. The detergent industry, frequently associated with negative environmental impacts, is also in need of new alternatives, such as biosurfactants/bioemulsifiers (BS/BE). These are naturally synthetized compounds, classified as amphiphilic, for having both hydrophobic and hydrophilic properties. Their application results in a reduction of the surface tension between two immiscible phases, facilitating the mixture of different substances such as water and oil, or water and air (Tavares et al., 2021). BS/BE present several advantages over conventional detergents, they have lower toxicity and greater biodegradability, resulting in lower negative impacts to both consumers and ecosystems. Furthermore, these compounds present antibiotic, antiviral and antioxidant properties. They can be used in a broad range of pH, temperature and salinity and are effective at small concentrations. This makes them interesting for many other industries, such as food, cosmetics, pharmaceutical and chemical. BS/BE are commonly produced by microorganisms found in particular environments such as oil wells, hydrocarbon contaminated soils and solid waste lixiviates. These compounds facilitate the access to hydrophobic nutrient sources abundant in these environments, while also increasing the resistance of the microorganisms to such toxic environments. Gordonia alkanivorans strain 1B, is a bacterium with significant biotechnological potential, which was isolated from oil contaminated soils (Alves et al., 2005). It is mostly known for its biodesulfurizing properties, carotenoid production and broad catabolic range (Silva et al., 2016). The present work focuses on the potential of this strain to produce BS/BE compounds, initial purification and characterization.
- Optimization of a biphasic biodesulfurization systemPublication . Silva, Tiago; Paixão, Susana M.; Roseiro, J. Carlos; Alves, LuísABSTRACT: Many of the new generation fuels, although more sustainable, share some of the problems inherent to fossil fuels. Depending on the biomass/material that originated them, they can present different contaminants that can lead to environmental problems. Sulfur is one of the most common and problematic contaminants in fuels. It is released into the atmosphere in the form of SOx, leading to the formation of acid rains, which cause drastic environmental and infrastructural problems, as well as several types of health issues. High sulfur concentrations in fuels also result in a loss of efficiency of motors and energy generation systems, mostly due to corrosion and catalyst poisoning. The current thermochemical desulfurization process, hydrodesulfurization (HDS), is energy demanding, pollutant and has low efficiency against more complex organosulfur molecules. This led researchers to look for new alternatives. Biodesulfurization (BDS), is, as the name implies, the biological removal of sulfur from fuels using microorganisms as living biocatalysts. If correctly employed this process could be more efficient and less pollutant, since microorganisms directly target the sulfur atoms, even those present in complex molecular structures, such as dibenzothiophene (DBT). Moreover, microbial activity occurs at much lower temperatures and pressures, without the need for metal catalysts, resulting in a lower energy demand. While BDS is a promising technology, it is still at a low development stage, mostly due to some bottlenecks, which have been hindering its large-scale application. Similarly, to other biotechnological processes, it presents lower reaction rates, when compared to HDS, since it depends on the use of living organisms as catalysts. Furthermore, it must be performed under conditions that allow the microorganisms to maintain biological activity, limiting the range of applications. These conditions vary greatly depending on the microorganism selected, and their optimization can significantly increase the biodesulfurization activity of a biocatalyst.
- Optimization of low sulfur jerusalem artichoke juice for fossil fuels biodesulfurization processPublication . Silva, Tiago; Paixão, Susana M.; Roseiro, J. Carlos; Alves, LuísMost of the world’s energy is generated from the burning of fossil fuels such as oil and its derivatives. When burnt, these fuels release into the atmosphere volatile organic compounds, sulfur as sulfur dioxide (SO2) and the fine particulate matter of metal sulfates. These are pollutants which can be responsible for bronchial irritation, asthma attacks, cardio-pulmonary diseases and lung cancer mortality, and they also contribute for the occurrence of acid rains and the increase of the hole in the ozone layer. For these reasons countries around the world imposed legal maxima to sulfur concentration on fuels. Forcing companies to develop methods of removing the sulfur contained in the oil. The most common is hydrodesulfurization which employs high pressures and temperatures associated with complex metal catalysts making it extremely expensive. So, it becomes important to explore alternatives such as biodesulfurization (BDS). This process is based on the use of microorganisms for the removal of sulfur form even from the most recalcitrant compounds at atmospheric pressure and temperature, making it cheaper and more eco-friendly. However it still presents some drawbacks, such as being easily inhibited in the presence of sulfates, which have been shown to have great inhibitory effect even in amounts as low as 6 mg/l [1]. In order to further reduce the costs associated with BDS it is possible to explore alternative carbon sources, as previously shown with carob pulp syrup and recycled paper sludge [1, 2]. The main objective of this work is the optimization of sulfate removal, from Jerusalem artichoke juice, in order to use it as an alternative carbon source for BDS.