From Microalgae Growth Promotion to the Production of Secondary Metabolites

Funding Information: F.Q.-N. and P.R.B. acknowledge receiving a Ph.D. fellowship (2022.10633.BD; 2021.07927.BD514, respectively) funded by FCT/MCTES. Funding Information: This research was conducted in the scope of the project “PhycoµBiome: Understanding and harnessing the power of the microalgae microbiome aiming the maximization of marine microalgae productivity” funded by Fundação para a Ciência e Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES, Portugal), grant number PTDC/BAA-BIO/1262/2020. The research was performed with the support of iNOVA4Health (UIDB/04462/2020 and UIDP/04462/2020) and the Associate Laboratory LS4FUTURE (LA/P/0087/2020) also funded by the FCT/MCTES. Publisher Copyright: © 2023 by the authors.Marine bacteria are a significant source of bioactive compounds for various biotechnological applications. Among these, actinomycetes have been found to produce a wide range of secondary metabolites of interest. Saccharopolyspora is one of the genera of actinomycetes that has been recognized as a potential source of these compounds. This study reports the characterization and genomic analysis of Saccharopolyspora sp. NFXS83, a marine bacterium isolated from seawater from the Sado estuary in Portugal. The NFXS83 strain produced multiple functional and stable extracellular enzymes under high-salt conditions, showed the ability to synthesize auxins such as indole-3-acetic acid, and produced diffusible secondary metabolites capable of inhibiting the growth of Staphylococcus aureus. Furthermore, when Phaeodactylum tricornutum was co-cultivated with strain NFXS83 a significant increase in microalgae cell count, cell size, auto-fluorescence, and fucoxanthin content was observed. Detailed analysis revealed the presence of clusters involved in the production of various secondary metabolites, including extracellular enzymes, antimicrobial compounds, terpenes, and carotenoids in the genome of strain NFXS83. Ultimately, these findings indicate that Saccharopolyspora sp. NFXS83 has a significant potential for a wide range of marine biotechnological applications.publishersversionpublishe

On the role of components of therapeutic hydrophobic deep eutectic solvent-based nanoemulsions sustainably produced by membrane-assisted nanoemulsification for enhanced antimicrobial activity

Stringent regulations and growing industrial interests have ensued the development of sustainable processes. Membrane assisted-nanoemulsification based on microengineered membranes has been explored for the sustainable production of therapeutic hydrophobic deep eutectic solvent (DES)-based nanoemulsions for enhanced antimicrobial applications. Hydrophobic DESs were synthesised by employing therapeutic terpenes: DL-menthol and thymol. To understand the mechanism of oil droplet detachment from the membrane when producing such nanoemulsions, the effect of hydrophilicity/hydrophobicity partition of the active membrane surface on the process performance was evaluated. Using a continuous phase cross-flow velocity of 0.32 m.s−1, a dispersed phase flowrate of 0.02 ml.min−1 and 2% (w/w) Tween 80 resulted in a DES-in-water nanoemulsion of 81.2 ± 0.9 nm droplet size. Novel observations like intrinsically reduced interfacial tension of 7.5 mN.m−1 between water and hydrophobic DES, and a hydrophobic DES wetting behaviour to both hydrophilic and hydrophobic active membrane surfaces were witnessed. Compared to DL-menthol, thymol or synthesised DES, the optimised DES-in-water nanoemulsions exhibited enhanced synergetic antimicrobial effect against Escherichia coli, Staphylococcus aureus and superior potency against Cutibacterium acnes, an acne inducing bacterial strain. These nanoemulsions were also cytocompatible with human keratinocytes and dermal fibroblasts. Lastly, membrane-assisted nanoemulsification manifested controlled size and monomodally distributed nanoemulsions compared to traditional ultrasound-driven emulsification.The authors would like to acknowledge Executive Agency for Education, Audiovisual & Culture (EACEA) of the European Commission for the scholarship grant of Erasmus Mundus Doctorate in Membrane Engineering (EUDIME) program to Syed Usman Taqui. Prof. Reyes Mallada and Dr. Ruth Lahoz from Nanoscience Institute of Aragon (INA), University of Zaragoza are acknowledged for their unconditional support in fabrication and characterization of metallic membranes. This work is also supported by the Associate Laboratory for Green Chemistry - LAQV which is financed by national funds from FCT/MCTES (UIDB/50006/2020). Authors M.T.B. Crespo, F.B. Gaspar and I.C. Leonardo acknowledge the financial support from the project “MobFood – Mobilizing scientific and technological knowledge in response to the challenges of the agri-food market” (POCI-01-0247-FEDER-024524) financed by European Regional Development Fund (ERDF), through the Incentive System to Research and Technological development, within the Portugal2020 Competitiveness and Internationalization Operational Program; iNOVA4Health - UID/Multi/04462/2013, a program financially supported by Fundação para a Ciência e Tecnologia/Ministério da Educação e Ciência, through national funds and co-funded by FEDER under the PT2020 Partnership Agreement; and INTERFACE Programme, through the Innovation, Technology and Circular Economy Fund (FITEC). This research was partially funded by the Spanish Ministry of Economy and Competitiveness (grant number CTQ2014-52384-R). V. Sebastian acknowledges the financial support from Ministerio de Ciencia, Innovación y Universidades, Programa Retos Investigación, Proyecto REF: RTI2018-099019-A-I00. G. Mendoza gratefully acknowledges the support from the Miguel Servet Program (MS19/00092; Instituto de Salud Carlos III). CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008 -2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III (Spain) with assistance from the European Regional Development Fund.Peer reviewe