Atmospheric plasma and UV polymerisation for developing sustainable anti-adhesive polyethylene terephthalate (PET) surfaces

Enhancing the hydrophilicity of polymeric materials is an important step for achieving anti-adhesiveness. Thus, in this study, atmospheric plasma as a pre-treatment was combined with a UV grafting process to obtain a durable surface modification on polyethylene terephthalate (PET). The most promising conditions for the atmospheric plasma process were found to be 15 kW power and 4 m/min speed, leading to a contact angle reduction from 70 ± 6° to approximately 30°. However, it was observed that these values increased over time due to the ageing and washing of the PET surface, ultimately causing it to recover its initial contact angle. Therefore, the plasma-pre-treated PET samples were further modified through a UV grafting process using sodium acrylate (NaAc) and 3-sulfopropyl acrylate potassium salts (KAc). The grafted acrylate PET samples exhibited contact angles of 8 ± 3° and 28 ± 13° for NaAc and KAc, respectively, while showing durability in ageing and washing tests. The dry film thicknesses for both samples were found to be 28 ± 2 μm. Finally, the anti-adhesive properties of the NaAc- and KAc-treated surfaces were evaluated using an Escherichia coli expressing YadA, an adhesive protein from Yersinia. The modified PET surfaces were highly effective in reducing bacterial adhesion by more than 90%.This work was supported by the ViBrANT project, which received funding from the EU Horizon 2020 Research and Innovation Programme under Marie Sklowdowska-Curie (grant agreement no. 765042), and the Portuguese Foundation for Science and Technology (FCT) (grant number UIDB/04469/2020).info:eu-repo/semantics/publishedVersio

Can superhydrophobic PET surfaces prevent bacterial adhesion?

Prevention of bacterial adhesion is a way to reduce and/or avoid biofilm formation, thus restraining its associated infections. The development of repellent anti-adhesive surfaces, such as superhydrophobic surfaces, can be a strategy to avoid bacterial adhesion. In this study, a polyethylene terephthalate (PET) film was modified by in situ growth of silica nanoparticles (NPs) to create a rough surface. The surface was further modified with fluorinated carbon chains to increase its hydrophobicity. The modified PET surfaces presented a pronounced superhydrophobic character, showing a water contact angle of 156° and a roughness of 104 nm (a considerable increase comparing with the 69° and 4.8 nm obtained for the untreated PET). Scanning Electron Microscopy was used to evaluate the modified surfaces morphology, further confirming its successful modification with nanoparticles. Additionally, a bacterial adhesion assay using an Escherichia coli expressing YadA, an adhesive protein from Yersinia so-called Yersinia adhesin A, was used to assess the anti-adhesive potential of the modified PET. Contrarily to what was expected, adhesion of E. coli YadA was found to increase on the modified PET surfaces, exhibiting a clear preference for the crevices. This study highlights the role of material micro topography as an important attribute when considering bacterial adhesion.This work was supported by the ViBrANT project that received funding from the EU Horizon 2020 Research and Innovation Programme under the Marie Sklowdowska-Curie, Grant agreement no 765042 and the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020.info:eu-repo/semantics/publishedVersio

Monitoring biotechnological processes through quantitative image analysis: application to 2-phenylethanol production by Yarrowia lipolytica

Available online 20 March 2023Quantitative image analysis (QIA) is a simple and automated tool for process monitoring that, when combined with chemometric techniques, enables the association of changes in microbiota morphology to various operational parameters. To that effect, principal component analysis, multilinear regression, and ordinary least squares methods were applied to the obtained dataset of the biotransformation conditions for Y. lipolytica through the monitor of yeast morphology, substrates (glycerol, L-phenylalanine - L-Phe) consumption and metabolites (2-phenylethanol 2-PE) production was developed. Glycerol and L-Phe were successfully monitored by the proposed approach, though with a lower monitoring ability for 2-PE, and mostly related to yeast and cluster size and proportion, yeasts contents and cluster morphology. The chemometric approach also allowed to identify significant morphological modifications related with the change in the stirring speed in the experiments at 600rpm, 600/400rpm (600rpm for 24h, and 400rpm until the end of the experiment) and in pH from 5.5 to 7.5. This work demonstrated, for the first time, that QIA combined with chemometric analysis can be considered a valuable tool to monitor biotechnological processes, namely the 2-PE production by Y. lipolytica, by analyzing yeast and cluster morphology.info:eu-repo/semantics/publishedVersio

Development of a cost-effective media for biosurfactants production by Pseudomonas aeruginosa

In the last years, the textile industry has shown a growing interest in biosurfactants due to their biocompatibility , biodegradability , and versatility at various pH and temperature ranges . These compounds have found applications as softeners, wetting agents, lubricants, foam stabilizers, and even in the scouring of wool. This study aims to develop an economically efficient medium for biosurfactant production by Pseudomonas aeruginosa #112. Firstly , waste cooking oils after treatment (WCOT), a residue rich in lipids, was evaluated as an inducer of biosurfactants production . Different concentrations of these substrates (1, 2.5, 5, and 10 % w/v) were tested, and glucose was used as a carbon source. In the experiments with 1 % of WCOT it was observed a significant (p 0.05) reduction in the surface tension from 48.4 mN/m to 34.8 mN/m, suggesting the biosurfactant production . Furthermore , rice husk (RH) and vine pruning (VP) residues were identified as alternative carbon sources for biosurfactants production, when combined with WCOT . Both residues are rich in cellulose, which can be broken down into free glucose. An enzymatic pre- treatment that combines xylanase and cellulase was used to hydrolyze residues and release free glucose . The obtained results demonstrate that the combination of 1 % OUAT with hydrolyzed RH or VP resulted in a substantial (53 %) reduction in surface tension. At the end of the fermentation, 1.65 g/L and 0.26 g/L of biosurfactant were recovered for the experiments with hydrolyzed PV and RH, respectively. Additionally, the critical micelle dilution results demonstrate that the two tested media allow biosurfactant production and effective reduction of the surface tension of distilled water , even at low concentrations . This is the first report of biosurfactant production using a mixture of these three agro-industrial residues , which can be very useful for the sustainable production of these promising molecules.The authors acknowledge the financial support from integrated project be@t – Textile Bioeconomy (TCC12-i01, Sustainable Bioeconomy No. 02/C12-i01/2022), promoted by the Recovery and Resilience Plan (RRP), Next Generation EU, for the period 2021 – 2026. The authors also acknowledge the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit.info:eu-repo/semantics/publishedVersio

Modification of PET surfaces with Gum Arabic towards its bacterial anti-adhesiveness using an experimental factorial design approach

Bacterial adhesion onto hospital material surfaces still represents a big healthcare issue, being preventive measures required to mitigate this problem, such as increasing material surface hydrophilicity. In the present study, gum Arabic, a hydrophilic polysaccharide, was used to modify the surface of polyethylene terephthalate (PET). Initial water contact angle (WCA) and WCA after several washing cycles were studied as response variables by a 24 full factorial design. Several reaction parameters, such as contact time between gum Arabic and PET, gum Arabic concentration, curing temperature and curing time for PET modification were investigated. The most significant parameters were found to be the curing temperature and curing time. The optimized parameters led to a WCA reduction from 70° to 27°. The modified PET samples were characterized using several techniques including AFM, colorimetric, ATR-FTIR and contact angle which further confirmed a successful surface modification. Furthermore, bacterial adhesion assays have clearly shown that the treated PET material was highly effective in preventing the bacterial adhesion of Escherichia coli expressing YadA, an adhesive protein from Yersinia so-called Yersinia adhesin. The use of design of experiments techniques allowed for successfully attaining a PET material with a high bacterial anti-adhesiveness, using a simple grafting approach.This work was supported by the ViBrANT project that received funding from the EU Horizon 2020 Research and Innovation Programme under the Marie Sklowdowska-Curie, Grant agreement no 765042 and the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020.info:eu-repo/semantics/publishedVersio

Two-step purification of epilactose produced by cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus

Epilactose is a functional sugar that can be produced from lactose using cellobiose 2-epimerase and it is considered a developing prebiotic. In that sense, the development of strategies to produce and purify epilactose is key for its wider use in the food industry. The aim of this work was to establish a food-grade purification strategy suitable to be scaled-up to an industrial level. Firstly, the epilactose was produced by enzymatic epimerization of lactose in a reaction catalyzed by the recombinant cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus produced by Saccharomyces cerevisiae. Then, to remove the unreacted lactose, a screening study was performed to find a suitable -galactosidase enzyme with high lactose hydrolysis capacity but low ability to convert the epilactose. The elimination of the generated monosaccharides was then attempted by microbial treatment using different microorganisms and using activated charcoal. The bakers yeast S. cerevisiae was proven to be the most suitable microorganism for glucose and galactose removal from the reaction mixture. Overall, an attractive and food-grade two-step process for epilactose recovery was established, resulting in a purity and yield of 87% and 76.4%, respectively. Additionally, the INFOGEST 2.0 static in vitro simulation of gastrointestinal food digestion was used, for the first time, to assess the resistance of epilactose (77% resistance) to the upper gastrointestinal tract conditions, reinforcing its potential to be used as prebiotic.BBC and JMF acknowledge their doctoral grants (SFRH/BD/ 132324/2017 and SFRH/BD/147286/2019, respectively) from the Portuguese Foundation of Science and Technology (FCT). This study was supported by FCT under the scope of the strategic funding of UIDB/ 04469/2020 unit.info:eu-repo/semantics/publishedVersio

Enhancement of lipase production by Yarrowia divulgata

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Collagen-coated magnetic nanoparticles to capture pathogens from biological samples

Conventional methods of diagnosing bacterial infections such as microbial culture and molecular techniques, while highly sensitive, rely on expensive equipment and highly skilled operators. There is a need for affordable and portable diagnostic systems which are simple to operate while preserving reliability. Pre-enrichment of bacteria present in a sample coupled with subsequent bacterial identification steps can serve as a simple yet effective diagnostic technique. Magnetic nanoparticles (MNPs) coated with collagen were used to demonstrate enrichment of E.coli recombinantly expressing adhesins YadA and UspA2 since these adhesins are known to target and adhere to host collagen. The MNPs were synthesized chemically and characterized by Fourier transform infrared spectroscopy and Dynamic light scattering and the most stable MNPs were selected. Adhesion assays were performed together with fluorescent microscopy imaging to assess the pre-enrichment of bacteria by the collagen MNPs. Capture of bacteria by the collagen MNPs was successfully observed and capture efficiency of the collagen MNPs for E.coli YadA and E.coli UspA2 was calculated to be 50% and 68% respectively.VibrANT H2020-MSCA-ITN-2017, agreement no. 765042. FCT UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004).info:eu-repo/semantics/publishedVersio

Agro-industrial wastes as alternative substrates for the production of prebiotic with Zymomonas mobilis

Fructooligosaccharides (FOS) are promising prebiotics in the relevant and increasing market of functional food. However, to achieve a more sustainable process, the industrial production of FOS should use cheap substrates. Zymomonas mobilis (ZM) has great potential for the production of FOS due to the presence of native enzymes (levansucrase) capable of metabolizing sucrose. In addition, ZM can use different carbon sources, such as molasses and sugarcane juice, which make the FOS production process cost-effective. In this study, sugarcane molasses (a potential replacement of sucrose) and corn step liquor (CSL) (a potential replacement of yeast extract (YE)), were used as nutrients for FOS production using ZM in an in vivo bioprocess approach. FOS production process from sucrose was first optimized and 52 g/L of FOS with a yield of 0.16 g/g was obtained. Afterwards, molasses and CSL were used as alternative nutrients. After studying different combinations of CSL and YE, the highest amount of FOS (54 g/L, with a yield of 0.18 g/g) was obtained with 12 g/L of CSL and 8 g/L of YE. In addition, 45 g/L of FOS were produced from molasses containing 200 g/L of sucrose, with a yield of 0.3 g/g. With this approach, it was possible to reduce around 5.5-times the cost associated with the FOS production medium. Moreover, this study proposed a sustainable process for the valorization of agro-industrial wastes contributing to the future Circular (Bio)Economy and the EU Green Deal.Cláudia Amorim, João Rainha, Beatriz B. Cardoso and Daniela Gomes acknowledge their grants (2020.0029.CEECIND, SFRH/BD/138325/2018, SFRH/BD/132324/2017 and SFRH/BD/04433/2020, respectively) from Portuguese Foundation for Science and Technology (FCT). The study received financial support from Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and by LABBELS – Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020.info:eu-repo/semantics/publishedVersio

Zymomonas mobilis an emerging microbial cell factory to produce prebiotics

info:eu-repo/semantics/publishedVersio