Germanane Monolayer Films as Antibacterial Coatings

Germanane (GeH), a graphane analogue, has attracted significant interest because of its optoelectronic properties; however, the environmental and biological effects of GeH have scarcely been investigated so far. Here we report a facile approach based on the Langmuir-Schaefer deposition to produce homogeneous and dense GeH monolayer films on various substrates. In view of possible applications and to extend the use of GeH to unexplored fields, we investigated its antibacterial activity for the first time and found that this promising 2D structure exhibits remarkable antibacterial activity against both Gram-negative and Gram-positive bacterial strains

Hybrid Nanomaterials of Magnetic Iron Nanoparticles and Graphene Oxide as Matrices for the Immobilization of beta-Glucosidase:Synthesis, Characterization, and Biocatalytic Properties

Hybrid nanostructures of magnetic iron nanoparticles and graphene oxide were synthesized and used as nanosupports for the covalent immobilization of β-glucosidase. This study revealed that the immobilization efficiency depends on the structure and the surface chemistry of nanostructures employed. The hybrid nanostructure-based biocatalysts formed exhibited a two to four-fold higher thermostability as compared to the free enzyme, as well as an enhanced performance at higher temperatures (up to 70°C) and in a wider pH range. Moreover, these biocatalysts retained a significant part of their bioactivity (up to 40%) after 12 repeated reaction cycles

Production, purification and characterization of thermostable hemicellulases

In the present Thesis, the hemicellulolytic system of the thermophilic fungi Chaetomium thermophilum IMI 291753, Thermomyces lanuginosus IMI 84400 and Sporotrichum thermophile ATCC 34628 was studied with regard to the optimization and characterization of xylanase production. Subsequently, the isolation, purification and characterization of β-xylosidase and endoxylanase from S. thermophile ATCC 34628 were accomplished. The optimization of xylanase production was based on a 32 central composite experimental design. The parameters studied were carbon and nitrogen sources. A second-order quadratic model and a response surface methodology were used to predict the optimum conditions for xylanase production. The results obtained here were confirmed by the experimental results that followed. In all cases, the raw materials for optimization trials were agro-industrial by-products of low cost, such as corn cob and wheat straw. The xylanase production optimization was followed by their characterization concerning thermostability and pH optimum. The characteristics of xylanases from all three fungi were proved to be hopeful for potential industrial applications. The ability of the enzyme produced by C. thermophilum IMI 291753 to be active in high pH values could be very useful for the treatment of alkaline pulps. Thermostable cellulase-free xylanase was produced by T. lanuginosus IMI 84400. The xylanase production was comparable to the production reported for other xylanase hyperproducing microorganisms and for different strains of the same microorganism, as well. Taking into account that low cost industrial wastes have been used as raw materials, the production of this xylanase would decrease the cost of production in an environmentally sound manner. Finally, two of the hemicellulolytic enzymes from S. thermophile ATCC 34628 were purified and characterized during this study: An extracellular endoxylanase and an intracellular β-xylosidase. The characterization of the two enzymes was made with regard to the molecular weight, thermostability, pH optimum, pI, specificity and inhibition. Based on the catalytic properties and the partial subsite mapping, the endo-xylanase purified from S. thermophile ATCC 34628 can be classified in family 11 of glycosyl hydrolases.Στην παρούσα διατριβή μελετάται το σύστημα ημικυτταρινασών από τους θερμόφιλους μύκητες Chaetomium thermophilum IMI 291753, Thermomyces lanuginosus IMI 84400 και Sporotrichum thermophile ATCC 34628. Η μελέτη περιλαμβάνει αρχικά την αριστοποίηση της παραγωγής και τον χαρακτηρισμό των ξυλανασών και στη συνέχεια, την απομόνωση και τον καθαρισμό μίας εξ’ αυτών καθώς και μιας β-ξυλοζιδάσης από τον S. thermophile ATCC 34628. Για την αριστοποίηση της παραγωγής των ξυλανασών από τους θερμόφιλους μύκητες C. thermophilum IMI 291753, T. lanuginosus IMI 84400 και S. thermophile ATCC 34628, κατά τη διάρκεια της καλλιέργειάς τους σε βυθισμένη καλλιέργεια χρησιμοποιήθηκε κεντρικός σχεδιασμός αστέρα 32. Οι αρχικές παράμετροι που μελετήθηκαν ήταν οι πηγές άνθρακα και αζώτου. Τα αποτελέσματα χρησιμοποιήθηκαν για την κατασκευή δευτεροβάθμιων γραμμικών μοντέλων. Μέσω αυτών των μοντέλων έγινε η πρόβλεψη των βέλτιστων συνθηκών για την παραγωγή των ξυλανασών με τη μέθοδο της επιφανειακής απόκρισης. Για κάθε μοντέλο το θεωρητικό βέλτιστο επαληθεύτηκε πειραματικά με πολύ ικανοποιητική προσέγγιση. Σε όλες τις περιπτώσεις, η παραγωγή των ημικυτταρινασών από τους τρεις μύκητες πραγματοποιήθηκε από αγροτοβιομηχανικά παραπροϊόντα, δηλαδή από εξαιρετικά φθηνές πρώτες ύλες όπως ο σπάδικας αραβοσίτου και το άχυρο σίτου. Την αριστοποίηση των συνθηκών παραγωγής των ξυλανασών ακολούθησε ο χαρακτηρισμός τους αναφορικά με την θερμοσταθερότητά τους και το βέλτιστο pH δράσης τους. Οι ξυλανάσες των τριών μικροοργανισμών παρουσίασαν χαρακτηριστικά ελπιδοφόρα για την βιομηχανική παραγωγή και εκμετάλλευσή τους. Η ικανότητα του ενζύμου από τον C. thermophilum IMI 291753 να δρα σε αλκαλικό pH, θα μπορούσε να βρει εφαρμογή στην κατεργασία αλκαλικών πολτών στη χαρτοβιομηχανία. Οι θερμοάντοχες ξυλανάσες, ελεύθερες κυτταρινασών, παράγονται από τον T. lanuginosus IMI 84400 σε παραγωγή συγκρίσιμη με την παραγωγή τους τόσο από άλλα στελέχη του ίδιου μικροοργανισμού, όσο και από άλλους υπερθερμόφιλους μικροοργανισμούς. Το γεγονός αυτό σε συνδυασμό με τις φθηνές πρώτες ύλες θα μπορούσε να συμβάλλει στη μείωση του κόστους της βιομηχανικής τους παραγωγής με φιλικό προς το περιβάλλον τρόπο. Τέλος, στα πλαίσια αυτής της διατριβής, πραγματοποιήθηκε η απομόνωση, ο χαρακτηρισμός και η μελέτη δύο ημικυτταρινολυτικών ενζύμων του S. thermophile ATCC 34628, μίας ενδοξυλανάσης και μίας β-ξυλοζιδάσης. Τα δύο ένζυμα μελετήθηκαν αναφορικά με το μοριακό τους βάρος, τη θερμοανθεκτικότητά τους, το βέλτιστο pH, το ισοηλεκτρικό τους σημείο, την εξειδίκευσή τους και τους αναστολείς τους. Τα αποτελέσματα της μελέτης για την απομονωμένη ενδοξυλανάση δείχνουν ότι το ένζυμο αυτό έχει παρόμοιες καταλυτικές ιδιότητες με ένζυμα που ανήκουν στην οικογένεια 11 των γλυκοϋδρολασών

Benefits of supplementation with microbial omega-3 fatty acids on human health and the current market scenario for fish-free omega-3 fatty acid

BackgroundGrowing evidence points to a link between specific fatty acids ingested through the diet and human health. Chain length, saturation degree, and position of double bonds in fatty acids determine their effect in humans. Omega-3 and omega-6 fatty acids have been recognized for their contribution to the prevention and/or treatment of diabetes, cancer, visual impairment, cardiovascular diseases, as well as neurological and musculoskeletal disorders. Scope and approachHumans cannot synthesize these fatty acids in sufficient amounts and need to absorb them through the diet. Oleaginous microalgae constitute a promising, sustainable source of such fatty acids, as they can accumulate up to 85% of lipids on a cell dry weight basis. Key findings and conclusionsThe present review summarizes the potential of oleaginous microalgae as a convenient, economical, and sustainable source of polyunsaturated fatty acids, and explores their beneficial role in human health. The growing prevalence of cardiovascular diseases and changing dietary preferences are driving the increasing demand for microbial omega-3 fatty acids. Following the COVID-19 pandemic, the importance of a healthy immune system has further strengthened the market for omega-3 fatty acids.Validerad;2023;Nivå 2;2023-05-12 (hanlid);Funder: Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT) (1137)Green and sustainable approach to valorise high saline and oily fish processing effluents for production of nutraceuticalsBoosting the squalene content in thraustochytrids by genetic engineering using CRISPR–Cas9 System to replace shark-based squalene as an adjuvant for COVID 2019 vaccin

Heterotrophic Cultivation of the Cyanobacterium <i>Pseudanabaena</i> sp. on Forest Biomass Hydrolysates toward Sustainable Biodiesel Production

Environmental pollution, greenhouse gas emissions, depletion of fossil fuels, and a growing population have sparked a search for new and renewable energy sources such as biodiesel. The use of waste or residues as substrates for microbial growth can favor the implementation of a biorefinery concept with reduced environmental footprint. Cyanobacteria constitute microorganisms with enhanced ability to use industrial effluents, wastewaters, forest residues for growth, and concomitant production of added-value compounds. In this study, a recently isolated cyanobacterium strain of Pseudanabaena sp. was cultivated on hydrolysates from pretreated forest biomass (silver birch and Norway spruce), and the production of biodiesel-grade lipids was assessed. Optimizing carbon source concentration and the (C/N) carbon-to-nitrogen ratio resulted in 66.45% w/w lipid content when microalgae were grown on glucose, compared to 62.95% and 63.79% w/w when grown on spruce and birch hydrolysate, respectively. Importantly, the lipid profile was suitable for the production of high-quality biodiesel. The present study demonstrates how this new cyanobacterial strain could be used as a biofactory, converting residual resources into green biofuel

Mycoprotein Production by Submerged Fermentation of the Edible Mushroom <i>Pleurotus ostreatus</i> in a Batch Stirred Tank Bioreactor Using Agro-Industrial Hydrolysate

The demand for cheap, healthy, and sustainable alternative protein sources has turned research interest into microbial proteins. Mycoproteins prevail due to their quite balanced amino acid profile, low carbon footprint and high sustainability potential. The goal of this research was to investigate the capability of Pleurotus ostreatus to metabolize the main sugars of agro-industrial side streams, such as aspen wood chips hydrolysate, to produce high-value protein with low cost. Our results indicate that P. ostreatus LGAM 1123 could be cultivated both in a C-6 (glucose)- and C-5(xylose)-sugar-containing medium for mycoprotein production. A mixture of glucose and xylose was found to be ideal for biomass production with high protein content and rich amino acid profile. P. ostreatus LGAM 1123 cultivation in a 4 L stirred-tank bioreactor using aspen hydrolysate was achieved with 25.0 ± 3.4 g L−1 biomass production, 1.8 ± 0.4 d−1 specific growth rate and a protein yield of 54.5 ± 0.5% (g/100 g sugars). PCA analysis of the amino acids revealed a strong correlation between the amino acid composition of the protein produced and the ratios of glucose and xylose in the culture medium. The production of high-nutrient mycoprotein by submerged fermentation of the edible fungus P. ostreatus using agro-industrial hydrolysates is a promising bioprocess in the food and feed industry