Insights on the laccase extraction and activity in ionic-liquid-based aqueous biphasic systems

Due to their catalytic properties, selectivity, and efficiency, enzymes are excellent biocatalysts. In particular, laccases are versatile multi-copper oxidases with great interest for a wide plethora of biotechnological and environmental applications. Even though several laccase-catalysed processes have been reported at an industrial level, the high costs of their downstream processing required to provide biocatalysts with high purity levels, stability and activity remains one of the main drawbacks when economically evaluating the overall processes. Aqueous biphasic systems based on ionic liquids (ILs) can be foreseen as a promising alternative approach for the extraction and activity maintenance/improvement of enzymes, essentially due to the designer solvents ability of ionic liquids. However, to take advantage of this feature and to use the full potential of IL-based aqueous biphasic systems, it is necessary to understand the effect of ILs as phase-forming constituents and how they affect the enzymes extraction and activity. In order to overcome the lack of information on this topic in the literature, in this work, IL-based aqueous biphasic systems were investigated to extract and enhance the laccase activity, in order to gather evidences that could be used to improve the enzymes downstream processing. To this end, a wide screening of imidazolium-, pyridinium-, pyrrolidinium-, piperidinium-, tetraalkylphosphonium-, and tetraalkylammonium-based ILs as phase-forming components of ABS was carried out. Furthermore, these ILs were used to create ABS combined with salts, polymers and used as adjuvants in polymer-based ABS. Most ABS comprising ILs revealed to be highly efficient extraction platforms, allowing the complete extraction of laccase for all the conditions tested, and with an enzyme activity enhancement by more than 50%. Overall, the obtained results demonstrate that laccase preferentially partitions to the most hydrophilic phase in ABS comprising ILs, both used as adjuvants or as phase-forming components, corresponding to the phase in which the IL is enriched. Furthermore, the IL chemical structure of the IL plays a significant role in the enzyme activity, where ILs with a higher number of hydroxyl groups seem to be relevant to improve the laccase activity.publishe

A flow-through strategy using supported ionic liquids for L-asparaginase purification

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Immobilization of L-asparaginase towards surface-modified carbon nanotubes

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes L-asparagine hydrolysis into L-aspartic acid and ammonia and is mainly applied in pharmaceutical and food industries [1]. The ASNase currently commercialized for pharmaceutical purposes is produced from two main bacterial sources: recombinant Escherichia coli and Erwinia chrysanthemi. However, some disadvantages are associated with its free form, such as the shorter half-life [2]. Immobilization of ASNase has been proposed as an efficient approach to overcome this limitation [3]. In this work, a straightforward method, including the functionalization of multi-walled carbon nanotubes (MWCNTs) through a hydrothermal oxidation treatment with nitric acid, and the immobilization of ASNase by adsorption over pristine and modified MWCNTs was investigated. Different operation conditions, including pH, contact time, ASNase/MWCNT mass ratio, and the operational stability of the immobilized ASNase were evaluated. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95%, under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5´10–3 g.mL-1of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), proving its suitability for application in industrial processes.publishe

Immobilization of L-asparaginase towards surface-modified carbon nanotubes

L-asparaginase (LA) is an enzyme that catalyzes L-asparagine hydrolysis into L-aspartic acid and ammonia and is mainly applied in pharmaceutical and food industries. The LA currently commercialized for pharmaceutical purposes is produced from two main bacterial sources: recombinant Escherichia coli and Erwinia chrysanthemi. However, some disadvantages are associated with its free form, such as the shorter half-life. Immobilization of LA has been proposed as an efficient approach to overcome this limitation. In this work, a straightforward method, including the functionalization of multi-walled carbon nanotubes (MWCNTs) through a hydrothermal oxidation treatment and the immobilization of LA by adsorption over pristine and modified MWCNTs was investigated. Different operation conditions, including pH, contact time, ASNase/MWCNT mass ratio, and the operational stability of the immobilized LA, were evaluated. The characterization of the LA-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial LA above 95%, under the optimized adsorption conditions (pH 8, 60 min of contact, and 1.510–3 g.mL-1 of LA). The LA-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), proving its suitability for application in industrial processes.publishe

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora

Characteristics, management, and outcomes of patients with left‐sided infective endocarditis complicated by heart failure: a substudy of the ESC‐EORP EURO‐ENDO (European infective endocarditis) registry

International audienc

Ion temperature and toroidal rotation in JET's low torque plasmas

This paper reports on the procedure developed as the best method to provide an accurate and reliable estimation of the ion temperature Ti and the toroidal velocity vφ from Charge-eXchange Recombination Spectroscopy (CXRS) data from intrinsic rotation experiments at the Joint European Torus with the carbon wall. The low impurity content observed in such plasmas, resulting in low active CXRS signal, alongside low Doppler shifts makes the determination of Ti and vφ particularly difficult. The beam modulation method will be discussed along with the measures taken to increase photon statistics and minimise errors from the absolute calibration and magneto-hydro-dynamics effects that may impact the CXRS passive emission