Percorrer por autor "Vigara, Javier"
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- Amino acids profile of 56 species of microalgae reveals that free amino acids allow to distinguish between phylogenetic groupsPublication . León-Vaz, Antonio; Giráldez, Inmaculada; Moreno-Garrido, Ignacio; Varela, João; Vigara, Javier; León, Rosa; Cañavate, José PedroMicroalgae represent a phototrophic resource with a high protein content, whose nutritional value is very high as a result of its amino acid profile. Although the total amino acid profile has been repeatedly described to change little among phylogenetic groups of microalgae, some variability has occasionally been reported. Part of this uncertainty is associated with the low phylogenetic diversity encompassed in the work to date and the high methodological variability between studies. Among these studies, very few have differentiated between total and free amino acid content for common microalgae samples. Thus, in the present work, the profile of total and free amino acids has been determined in a diverse group composed of 56 species of microalgae belonging to 7 phyla. A multivariate analysis of the total amino acid profile in the studied microalgae group revealed close amino acid patterns throughout microalgae phylogeny and agreed with results obtained from similar analysis performed with published data. Conversely, the free amino acid profile strongly differentiated between phylogenetic groups. On the one hand, species of Cyanobacteria, Plantae, Cryptophyta, and Bacillariophyta showed close free amino acid patterns, characterized by the highest abundance of free glutamic acid. Ochrophyta species were particularly rich in free proline, while the free amino acid profile of Miozoa and Haptophyta species stood out from the rest of the phylogenetic groups for their outstanding levels of the two essential amino acids phenylalanine and lysine. Haptophyta species were also characterized by their much higher free tyrosine content.
- Antioxidant, antimicrobial, and bioactive potential of two new haloarchaeal strains isolated from Odiel Salterns (Southwest Spain)Publication . Gómez-Villegas, Patricia; Vigara, Javier; Vila, Marta; Varela, João; Barreira, Luísa; Léon, RosaThe need to survive in extreme environments has furnished haloarchaea with a series of components specially adapted to work in such conditions. The possible application of these molecules in the pharmaceutical and industrial fields has received increasing attention; however, many potential bioactivities of haloarchaea are still poorly explored. In this paper, we describe the isolation and identification of two new haloarchaeal strains from the saltern ponds located in the marshlands of the Odiel River, in the southwest of Spain, as well as the in vitro assessment of their antioxidant, antimicrobial, and bioactive properties. The acetone extract obtained from the new isolated Haloarcula strain exhibited the highest antioxidant activity, while the acetone extracts from both isolated strains demonstrated a strong antimicrobial activity, especially against other halophilic microorganisms. Moreover, these extracts showed a remarkable ability to inhibit the enzyme cyclooxygenase-2 and to activate the melanogenic enzyme tyrosinase, indicating their potential against chronic inflammation and skin pigmentation disorders. Finally, the aqueous protein-rich extracts obtained from both haloarchaea exhibited an important inhibitory effect on the activity of the acetylcholinesterase enzyme, involved in the hydrolysis of cholinergic neurotransmitters and related to several neurological diseases.
- Biochemical characterization of the amylase activity from the New Haloarchaeal Strain Haloarcula sp. HS isolated in the Odiel MarshlandsPublication . Gómez-Villegas, Patricia; Vigara, Javier; Romero, Luis; Gotor, Cecilia; Raposo, Sara; Gonçalves, Brígida; Léon, RosaAlpha-amylases are a large family of α,1-4-endo-glycosyl hydrolases distributed in all kingdoms of life. The need for poly-extremotolerant amylases encouraged their search in extreme environments, where archaea become ideal candidates to provide new enzymes that are able to work in the harsh conditions demanded in many industrial applications. In this study, a collection of haloarchaea isolated from Odiel saltern ponds in the southwest of Spain was screened for their amylase activity. The strain that exhibited the highest activity was selected and identified as Haloarcula sp. HS. We demonstrated the existence in both, cellular and extracellular extracts of the new strain, of functional α-amylase activities, which showed to be moderately thermotolerant (optimum around 60 ◦C), extremely halotolerant (optimum over 25% NaCl), and calcium-dependent. The tryptic digestion followed by HPLC-MS/MS analysis of the partially purified cellular and extracellular extracts allowed to identify the sequence of three alpha-amylases, which despite sharing a low sequence identity, exhibited high three-dimensional structure homology, conserving the typical domains and most of the key consensus residues of α-amylases. Moreover, we proved the potential of the extracellular α-amylase from Haloarcula sp. HS to treat bakery wastes under high salinity conditions.
- Using agro-industrial wastes for mixotrophic growth and lipids production by the green microalga Chlorella sorokinianaPublication . León-Vaz, Antonio; León, Rosa; Díaz-Santos, Encarnación; Vigara, Javier; Raposo, SaraThere has been growing interest in the use of microalgae for the production of biofuels, but production costs continue to be too high to compete with fossil fuel prices. One of the main limitations for photobioreactor productivity is light shielding, especially at high cell densities. The growth of the green microalga Chlorella sorokiniana, a robust industrial species, has been evaluated under different trophic conditions with traditional carbon sources, such as glucose and sucrose, and alternative low cost carbon sources, such as carob pod extract, industrial glycerol and acetate-rich oxidized wine waste lees. The mixotrophic cultivation of this microalga with wine waste lees alleviated the problems of light shielding observed in photoautotrophic cultures, improving specific growth rate (0.052 h-1) compared with the other organic sources. The fed-batch mixotrophic culture of Chlorella sorokiniana in a 2 L stirred tank reactor, with optimized nutritional conditions, 100 mM of acetate coming from the oxidized wine waste lees and 30 mM of ammonium, produced an algal biomass concentration of 11 g L-1 with a lipid content of 38 % (w/w). This fed-batch strategy has been found to be a very effective means to enhance the biomass and neutral lipid productivity.