Departamento de Ingeniería Química

Complete microbial encapsulation within alginate-εPLL core-shell hydrogel beads enables spatially distributed co-cultures and bioreactor scale-up

Complete microbial encapsulation within alginate-εPLL core-shell hydrogel beads enables spatially distributed co-cultures and bioreactor scale-up Amaro-Cruz, Alba; Carmona-Bravo, Juana M.; García Román, Miguel; Moya-Ramírez, Ignacio Achieving stable and reproducible microbial co-cultures requires tools to control the population balance among species. To address this challenge, here we present an effective method for microbial encapsulation relying on alginate-core hydrogel beads coated with an alternating ε-poly-l-lysine/alginate multilayer shell (εPLL-HB). This procedure combines two features that are rarely reported together: (i) the complete containment of several microbial species (prokaryotic and eukaryotic) under diverse conditions, while (ii) supporting their controlled growth inside the εPLL-HB. The lack of cell leakage from the capsules is often overlooked and has only been achieved with shells prepared by polymerization reactions. In contrast, εPLL-HB manufacturing is simpler and biocompatible, only relying on non-covalent interactions. In this regard, εPLL showed better performance than chitosan and α-poly-l-lysine, two of the biomaterials most used as coating agents in core-shell encapsulation. Therefore, εPLL-HB allowed us to build spatially distributed co-cultures, effectively balancing populations of microorganisms with different growth rates and interactions. We also demonstrate that εPLL-HB are scalable to stirred-tank bioreactor cultures, proving their utility in large-scale applications. Furthermore, microbial-loaded εPLL-HB maintained their encapsulation efficacy and cell viability after long-term storage at −80 °C and provided protection against toxic compounds in lignocellulosic-derived media. The superior microbial containment, scalability, structural integrity, and chemical resistance of εPLL-HB, combined with their cost-effective and simple preparation, make them a versatile tool for engineering synthetic microbial consortia, with broad applicability in biotechnological processes. The authors acknowledge funding through grant TED2021-131194 A-I00 funded by MCIN/AEI/10.13039/501100011033 and NextGenerationEU/PRTR. IMR also acknowledges the ﬁnancial support by grant RYC2022-037570-I funded by MICIU/AEI/10.13039/501100011033 and by ESF+. Funding for open access charge: Universidad de Granada / CBUA.

Encapsulation of echium oil by electrospraying and mono- or coaxial spray-drying using plant protein hydrolysates as emulsifiers

Encapsulation of echium oil by electrospraying and mono- or coaxial spray-drying using plant protein hydrolysates as emulsifiers Sisconeto Bisinotto, Mariana; Alves Castro, Inar; Guadix Escobar, Emilia María; García Moreno, Pedro Jesús The development of echium oil-loaded nano-microcapsules by electrospraying, mono- and coaxial spray-drying was investigated. Brewers' spent grains (BT) or defatted grape seed flour (GT) hydrolysates were used as plant-based emulsifiers. The oxidative stability of the capsules was assessed by Electron Spin Resonance (ESR). Electrosprayed particles had narrow size distribution, mostly <1.5 μm, increased specific surface area and low encapsulation efficiency (EE =61%). On the contrary, capsules produced with mono- and coaxial spray-drying mostly ranged from 2 to 10 μm and had higher EE (>80%), showing higher oxidative stability. BT, exhibiting higher emulsifying capacity and leading to more viscoelastic interfacial films than GT, led to microcapsules with higher oxidative stability with no difference between mono- and coaxial processes. In contrast, coaxial spray-drying, resulting in capsules with core-shell structure, reduced oil leakage when using the less powerful emulsifier GT, enhancing oxidative stability when compared to the monoaxial process.

Mechanistic in vitro evaluation of surfactant-induced skin irritation: Correlating micellar physicochemistry with 3D reconstructed human epidermis, zein, and ecotoxicity endpoints

Mechanistic in vitro evaluation of surfactant-induced skin irritation: Correlating micellar physicochemistry with 3D reconstructed human epidermis, zein, and ecotoxicity endpoints Lechuga Villena, Manuela María; Ríos Ruiz, Francisco; Ávila Sierra, Alejandro; Herrero, Elena; Fernández Serrano, Mercedes The dermal irritation potential of representative anionic, non-ionic, amphoteric, and ethoxylated surfactants was evaluated using three complementary in vitro approaches: the zein protein solubilization assay, reconstructed human epidermis (RhE) cell viability testing, and the Vibrio fischeri bioluminescence inhibition assay to assess ecotoxicity. Surfactants forming small and highly mobile micelles generally tended to exhibit higher zein numbers, reduced RhE viability, and lower EC50 values, indicating increased irritant and toxic potential. In contrast, non-ionic surfactants forming larger and less mobile aggregates showed lower protein solubilization, higher cell viability, and reduced bacterial toxicity. Multivariate principal component analysis demonstrated that micellar diffusivity, with additional contributions from electrostatic character and hydrophilic-lipophilic balance, represents a major physicochemical axis associated with biological variability, whereas micellar size plays a secondary structural role. This integrated framework provides mechanistic insight into surfactant-induced irritation and supports the rational selection and design of safer, more sustainable surfactant systems.

Fixed-bed column performance of amino-functionalized MCM-41 mesoporous silica for Cr(VI) removal: Optimization of operating conditions and regeneration studies

Fixed-bed column performance of amino-functionalized MCM-41 mesoporous silica for Cr(VI) removal: Optimization of operating conditions and regeneration studies Martin, P.P.; Fellenz, N.; Calero De Hoces, Francisca Mónica; Martín Lara, M.A.; Martín Lara, María Ángeles

Bifunctional magnetic Co3O4-B/C catalysts for the thermochemical conversion of non-reciclable plastic waste

Bifunctional magnetic Co3O4-B/C catalysts for the thermochemical conversion of non-reciclable plastic waste Ortega García, Francisco; Jiménez-Rodríguez, Lucía; Blázquez, G.; Calero De Hoces, Francisca Mónica; Muñoz Batista, Mario Jesús The work presents a catalytic study focused on the valorization of the gas fraction generated during the pyrolysis of non-recyclable plastic waste. It encompasses both the development of catalytic materials and the optimization of a two-step process aimed at improving the gas composition toward a hydrogen-rich stream. The catalysts were synthesized through a simple and scalable solvent-less approach. The most promising material, a ternary Co₂O₃/B/Carbon system, not only exhibited remarkable catalytic activity but also displayed magnetic properties that facilitate its separation during the in situ pyrolysis stage, achieving 103.3 mmol of H2 produced at 1 h (5.2 mmol of H2 g−1 of the plastic), with H₂/CO > 2.0 and H₂/(CO + CO₂) of 1.6, representing a 43 % increase in the amount of H₂ produced compared to single-stage operation. The study identifies and discusses the roles of the Co-related metallic components supported on carbon, as well as the contribution of the minor boron species. Overall, this work provides clear evidence of the potential of a two-step catalytic configuration for the valorization of plastic residues that currently accumulate in landfills.