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Browsing UB - Artigos em revistas internacionais by Field of Science and Technology (FOS) "Engenharia e Tecnologia::Biotecnologia Industrial"
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- Alternative feedstocks for high-quality biodiesel: Lipid production from eucalyptus bark hydrolysate by Yarrowia lipolytica W29 using different cultivation modesPublication . Dias, Bruna; Lopes, Marlene; Marques, Susana; Gírio, Francisco; Belo, IsabelABSTRACT: Microbial lipids produced by yeasts from lignocellulosic biomass are a promising feedstock for the biodiesel industry, providing a renewable energy source as an alternative to traditional fossil fuels. This study investigated the potential of Yarrowia lipolytica W29 to produce lipid-rich biomass from undetoxified sugar-concentrated eucalyptus bark hydrolysate (EBH). The lipid concentrations achieved in batch cultures (13.4 g L-1) were the highest for wild-type Y. lipolytica strains in lignocellulosic hydrolysates. Different two-stage cultivation modes (repeated batch, continuous-feeding fed-batch, and pulse fed-batch) were studied to enhance biomass and lipid production. The cell and lipid mass was higher in pulse fed-batch and continuous-feeding fed-batch cultures than batch cultures. Production of citric acid, a side product of industrial interest, was improved in the continuous-feeding fed-batch culture. Microbial lipids produced by Y. lipolytica W29 were highly unsaturated and mainly composed of oleic acid (50% to 53%). The estimated properties of the biodiesel that would be obtained from these intracellular lipids would meet the international biodiesel standards EN 14214 and ASTM D6751. This study demonstrates the feasibility of using EBH for Y. lipolytica lipid production and promotes the sustainable production of high-quality biodiesel from lignocellulosic feedstocks.
- Fractionation of macroalgae carbohydrates using hydrothermal and dilute inorganic salt pretreatments to produce oligosaccharides and furansPublication . Martins, Pedro L.; Andrade, Cristiana; Duarte, Luís; Reis, Alberto; Pereira, Helena; Carvalheiro, FlorbelaABSTRACT: Furans are among the most important compounds derived from biomass, providing conversion pathways for sustainable alternatives to petroleum-based fuels and materials. Furfural, 5-hydroxymethylfurfural (5-HMF), and 5-methylfurfural (5-MF) are furans that can be obtained by carbohydrate dehydration under acidic conditions at elevated temperature and pressure. One of the mechanisms to produce these compounds from lignocellulosic materials relies on prior fractionation of biomass carbohydrates and further dehydration catalysis. However, this is a costly and technically challenging method and it would be advantageous to develop a one-pot conversion mechanism that facilitates simultaneous biomass fractionation and conversion to furans. Ulva lactuca is an alga that has the advantage of being lignin-free and rich in glucose, rhamnose, and xylose, which are ideal for producing 5-HMF, 5-MF, and furfural, respectively. The high diversity of sugar constituents is also relevant for the production of added-value oligosaccharides. Catalysis with inorganic salts has been reported as a successful tool for biomass upgrading to furans when combined with hydrothermal pretreatments, and could provide a cheap and environmentally friendly one-step methodology for furan production. This study therefore aimed to investigate the effect of hydrothermal and dilute acid pretreatments, as well as treatment with inorganic salt solutions (ferric chloride, ferric nitrate, and aluminium nitrate) on U. lactuca biomass to produce oligosaccharides, monosaccharides, and furans (furfural, 5-HMF, and 5-MF). These methods resulted in a maximum sugar solubilization of 65% in non-salt-assisted hydrothermal pretreatments and 84% in salt-assisted hydrothermal pretreatments, with inorganic salt catalysis also resulting in 100% xylose, 36% glucose, and 46% rhamnose conversion to the respective furans.
- New Insights on Gordonia alkanivorans Strain 1B Surface-Active Biomolecules: Gordofactin PropertiesPublication . Tavares, João; Paixão, Susana M.; Silva, Tiago; Alves, LuísABSTRACT: Biosurfactants/bioemulsifiers (BSs/BEs) can be defined as surface-active biomolecules produced by microorganisms with a broad range of applications. In recent years, due to their unique properties like biodegradability, specificity, low toxicity, and relative ease of preparation, these biomolecules have attracted wide interest as an eco-friendly alternative for several industrial sectors, escalating global microbial BS/BE market growth. Recently, Gordonia alkanivorans strain 1B, a bacterium with significant biotechnological potential, well known for its biodesulfurizing properties, carotenoid production, and broad catabolic range, was described as a BS/BE producer. This study focuses on the characterization of the properties of the lipoglycopeptide BSs/BEs produced by strain 1B, henceforth referred to as gordofactin, to better understand its potential and future applications. Strain 1B was cultivated in a chemostat using fructose as a carbon source to stimulate gordofactin production, and different purification methods were tested. The most purified sample, designated as extracted gordofactin, after lyophilization, presented a specific emulsifying activity of 9.5 U/mg and a critical micelle concentration of 13.5 mg/L. FT-IR analysis revealed the presence of basic hydroxyl, carboxyl, ether, amine/amide functional groups, and alkyl aliphatic chains, which is consistent with its lipoglycopeptide nature (60% lipids, 19.6% carbohydrates, and 9% proteins). Gordofactin displayed remarkable stability and retained emulsifying activity across a broad range of temperatures (30 degrees C to 80 degrees C) and pH (pH 3-12). Moreover, a significant tolerance of gordofactin emulsifying activity (EA) to a wide range of NaCl concentrations (1 to 100 g/L) was demonstrated. Although with a great loss of EA in the presence of NaCl concentrations above 2.5%, gordofactin could still tolerate up to 100 g/L NaCl, maintaining about 16% of its initial EA for up to 7 days. Furthermore, gordofactin exhibited growth inhibition against both Gram-positive and Gram-negative bacteria, and it demonstrated concentration-dependent free radical scavenging activity for 2,2-diphenyl-1-picrylhydrazyl (IC50 approximate to 1471 mg/L). These promising features emphasize the robustness and potential of gordofactin as an eco-friendly BS/BE alternative to conventional surfactants/emulsifiers for different industrial applications.