Loading...
Research Project
Ethanol production from microalgae and lignocellulosic biomass.
Funder
Authors
Publications
Antioxidant potential of extracts of Chromochloris zofingiensis cultivated in pilot-scale outdoor tubular photobioreactors under nitrogen limitation
Publication . Corrêa, Priscila S.; M. Júnior, Wilson G. de; Caetano, Nídia
Chromochloris zofingiensis is known to be able to produce large amounts of astaxanthin and also to coproduce other molecules with antioxidant properties. Outdoor cultivation is the cheapest way for large-scale production; however, the unstable weather conditions can hinder the productivity of the biomass and the target product. The final biomass (0.92 g·L−1) and total carotenoids (0.55 mg·g−1) concentration achieved in outdoor cultivation (i.e., during autumn in Porto, Portugal) had no statistically significant difference compared to control cultivation (i.e., constant temperature, 18 °C, and light intensity, 4000 lx) (1.36 g·L−1 and 0.56 mg·g−1, respectively), however the biomass productivity was about threefold lower. Regarding the antioxidant potential, methanolic extracts from outdoor cultivation presented one of the highest values for radical scavenging ability (44.2 %) and ferrous-ion chelating ability (59.1 %), similarly to the results obtained by ethanolic extracts from indoor cultivation under nitrogen limitation. Highest total antioxidant capacities were observed in ethanolic extracts varying from 120.0 to 185.2 mg GAE·g−1.
Microalgae for biotechnological applications: Cultivation, harvesting and biomass processing
Publication . Morais Júnior, Wilson Galvão; Gorchich, Malihe; Corrêa, Priscila S.; Martins, António A.; Mata, Teresa M.; Caetano, Nídia
In either unicellular or multi-cellular form, microalgae are photosynthetic microorganisms, mainly known for being part of the human diet in several world regions. More recently, they have been in the spotlight of researchers, not only because of their nutritional value, but also due to their high value-added components. This work reviews five microalgae genera: Dunaliella, Botryococcus, Chlamydomonas, Chlorella and Arthrospira, considered among the most promising for commercial biotechnological applications. The analysis shows that, although the research paradigms are generally shared among species, parameterization changes of culture environment and stress conditions, several applications can be envisaged for the cultivated species, which is discussed in this work. Besides, several applications in which these microalgae are being widely used, or are intended to be used, are analyzed and discussed. The potential applications depend on the type of metabolites found in each microalgae species, which is discussed in this work, giving examples of application and describing methods for their cultivation, harvesting and biomass processing. Thus, in addition to being used in human diet supplementation, microalgae can be used as ingredients for animal feed, medicines, cosmetics pigments, biofuels, bioplastics and biostimulants.
Sugarcane Bagasse Saccharification by Enzymatic Hydrolysis Using Endocellulase and β-glucosidase Immobilized on Different Supports
Publication . Morais Júnior, Wilson Galvão; Pacheco, Thályta F.; Gao, Shipeng; Martins, Pedro A.; Guisán, José M.; Caetano, Nídia
The saccharification of sugarcane bagasse by enzymatic hydrolysis is one of the most promising processes for obtaining fermentable sugar to be used in the production of second-generation ethanol. The objective of this work was to study the immobilization and stabilization of two commercial enzymes: Endocellulase (E-CELBA) in dextran coated iron oxide magnetic nanoparticles activated with aldehyde groups (DIOMNP) and β-glucosidase (E-BGOSPC) in glyoxyl agarose (GLA) so that their immobilized derivatives could be applied in the saccharification of pretreated sugarcane bagasse. This was the first time that the pretreated sugarcane bagasse was saccharified by cascade reaction using a endocellulase immobilized on dextran coated Fe2O3 with aldehyde groups combined with a β-glucosidase immobilized on glyoxyl agarose. Both enzymes were successfully immobilized (more than 60% after reduction with sodium borohydride) and presented higher thermal stability than free enzymes at 60, 70, and 80 °C. The enzymatic hydrolysis of the sugarcane bagasse was carried out with 15 U of each enzyme per gram of bagasse in a solid-liquid ratio of 1:20 for 48 h at 50 °C. Under these conditions, 39.06 ± 1.18% of the cellulose present in the pretreated bagasse was hydrolyzed, producing 14.11 ± 0.47 g/L of reducing sugars (94.54% glucose). In addition, DIOMNP endo-cellulase derivative maintained 61.40 ± 1.17% of its enzymatic activity after seven reuse cycles, and GLA β-glucosidase derivative maintained up to 58.20 ± 1.55% of its enzymatic activity after nine reuse cycles.
Microalgae Biomolecules: Extraction, Separation and Purification Methods
Publication . Corrêa, Priscila S.; Morais Júnior, Wilson Galvão; Martins, António A.; Caetano, Nídia; Mata, Teresa M.
Several microalgae species have been exploited due to their great biotechnological potential for the production of a range of biomolecules that can be applied in a large variety of industrial sectors. However, the major challenge of biotechnological processes is to make them economically viable, through the production of commercially valuable compounds. Most of these compounds are accumulated inside the cells, requiring efficient technologies for their extraction, recovery and purification. Recent improvements approaching physicochemical treatments (e.g., supercritical fluid extraction, ultrasound-assisted extraction, pulsed electric fields, among others) and processes without solvents are seeking to establish sustainable and scalable technologies to obtain target products from microalgae with high efficiency and purity. This article reviews the currently available approaches reported in literature, highlighting some examples covering recent granted patents for the microalgae’s components extraction, recovery and purification, at small and large scales,
in accordance with the worldwide trend of transition to bio-based products.
Acid pretreatment of sugarcane biomass to obtain hemicellulosic hydrolisate rich in fermentable sugar
Publication . Morais Júnior, Wilson Galvão; Pacheco, Thályta F.; Corrêa, Priscila S.; Martins, António A.; Mata, Teresa M.; Caetano, Nídia
The objective of this work was to find the ideal pretreatment conditions with high efficiency to obtain a hydrolyzate rich in fermentable sugars and low possible inhibitors levels. Thus, it was applied diluted phosphoric acid to pretreat the sugarcane biomass. Through a Central Composite Design, it was evaluated the influence of temperature, operating time and acid concentration. The pretreatment efficiency was verified by the concentration of total monosaccharides in the liquid fraction after the reaction. The phosphoric acid concentration of 4.95% at 80 °C, during 375 min, resulted in a hemicellulosic hydrolyzate with the highest concentration of fermentable sugars (saccharification greater than 99%), with the absence of HMF and furfural, and relatively low amounts of acetic acid.
Organizational Units
Description
Keywords
Contributors
Funders
Funding agency
European Commission
Funding programme
H2020
Funding Award Number
867473