The effect of hydrodynamic conditions in Corynebacterium glutamicum growth

[Excerpt] Corynebacterium glutamicum is a facultative anaerobic, gram-positive bacterium with a GRAS status that grows fast and achieves high cell densities. C. glutamicum is commonly used in amino acids production, and is also able to convert sugars in organic acids (OA) and alcohols in specific conditions: anaerobic and limited-oxygen environments. In these conditions, the carbon metabolism is modified, namely the flux shifts from the pentose phosphate pathway to glycolysis and the TCA cycle flux decreases and consequently bacterial growth is strongly affected [1,2]. (...

Thermoelectric and structural properties of transparent Sb-Doped ZnO thin films sputtered in a confocal geometry

This study focuses on understanding the influence of low Sb doping on ZnO’s electrical, optical, and thermoelectrical properties, while also studying its structural and morphological parameters. For this, several ZnO films with varying Sb target current densities, in the range of 0–0.27 mA/cm2, were produced by DC magnetron sputtering in a confocal geometry. As a result, thin ZnO:Sb films with an average transparency in the visible region greater than 80% are obtained, revealing for optimized conditions an absolute Seebeck coefficient of 100 µV/K and a respective power factor of 1.1 mW·m−1·K−2 at 300 K, effectively modifying the electrical, optical, and thermoelectrical properties of the material and ensuring its suitability for heat harvesting applications. From atom probe tomography experiments, a larger Zn content is registered at triple junctions of the grain boundary, which matches the approximately 25 nm crystallite grain size derived from the X-ray diffraction analysis.This research is funded by FCT/PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023. Joana M. Ribeiro is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D grant SFRH/BD/147221/2019. This work (proposal ID 2021-025-030112) was carried out with the support of the Karlsruhe Nano Micro Facility (KNMFi, www.knmf.kit.edu, accessed on 8 March 2023), a Helmholtz Research Infrastructure at Karlsruhe Institute of Technology (KIT, www.kit.edu, accessed on 8 March 2023)

Unveiling the Antifouling Performance of Different Marine Surfaces and Their Effect on the Development and Structure of Cyanobacterial Biofilms

Since biofilm formation by microfoulers significantly contributes to the fouling process, it is important to evaluate the performance of marine surfaces to prevent biofilm formation, as well as understand their interactions with microfoulers and how these affect biofilm development and structure. In this study, the long-term performance of five surface materials-glass, perspex, polystyrene, epoxy-coated glass, and a silicone hydrogel coating-in inhibiting biofilm formation by cyanobacteria was evaluated. For this purpose, cyanobacterial biofilms were developed under controlled hydrodynamic conditions typically found in marine environments, and the biofilm cell number, wet weight, chlorophyll a content, and biofilm thickness and structure were assessed after 49 days. In order to obtain more insight into the effect of surface properties on biofilm formation, they were characterized concerning their hydrophobicity and roughness. Results demonstrated that silicone hydrogel surfaces were effective in inhibiting cyanobacterial biofilm formation. In fact, biofilms formed on these surfaces showed a lower number of biofilm cells, chlorophyll a content, biofilm thickness, and percentage and size of biofilm empty spaces compared to remaining surfaces. Additionally, our results demonstrated that the surface properties, together with the features of the fouling microorganisms, have a considerable impact on marine biofouling potential

Yttria/ceria stabilized zirconia composites: evaluation of microstructural, mechanical and color properties for biomedical applications

[Excerpt] 3-mol% Yttria-Stabilized Tetragonal Zirconia Polycrystal (3Y-TZP), a ceramic biomaterial, has been widely used in the dentistry field due to its biocompatibility, tooth-like color and mechanical properties [1]. Despite these advantages, its physical and mechanical properties tend to degrade as a result of a low-temperature aging process induced by its sensitivity to low-temperature degradation (LTD) when it is in contact with water that is already at human body temperature [2]. Because of this, many studies have been performed aiming at avoiding this phenomenon by replacing 3Y-TZP by 12 mol% ceria stabilized tetragonal zirconia polycrystal (12Ce-TZP). Nevertheless, compared to 3Y-TZP, 12Ce-TZP has lower strength which is partly related to its larger grain size [3]. [...]This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020. Additionally, this work was also supported by FCT through the grant SFRH/BD/146324/2019

A dynamical model for the fermentative production of fructooligosaccharides

In this paper a detailed mathematical model is presented for the fermentative production of fructo-oligosaccharides with Aspergillus sp. The model accounts for hydrolysis and transfructolization reactions, as well as biomass formation and it contains 27 parameters that were determined from experimental data using a System Biology toolbox with the Simulated Annealing method for curve fitting. Several additional experiments were performed in bioreactors where the time variation of 7 state variables (Sucrose, Glucose, Fructose, 1-Kestose, Nystose, 1-fructosyl nystose and Biomass) was measured. Experimental data were compared with results from simulations using the estimated parameters and it was verified that the model can predict the FOS production profile. The good agreement between simulated and experimental data was verified by calculating the relative percentage deviation modulus, which was lower than 10% for all cases except one. The derived and validated model can be used for process optimization, for example for indicating which fed-batch strategy could be used to improve the production of FOS while minimizing glucose concentration

Towards a genome-wide transport systems encoding genes tracker

[Excerpt] Introduction: TRIAGE, is a tool currently embedded in merlin , which performs the identification of transport systems and automatically generates transport reactions for every metabolite transported by those carriers. Reactions generated by TRIAGE can be directly integrated in GSM models, as all metabolites involved have KEGG and/or ChEBI identifiers. Up to our knowledge, this is the only tool capable of identifying and generating such reactions. [...]by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorteoperation (NORTE -01-0145-FEDER- 000004) funded by the European Regional Development Fund under the scope of Norte2020 -Programa Operacional Regional do Norteinfo:eu-repo/semantics/publishedVersio

Antifouling Marine Coatings with a Potentially Safer and Sustainable Synthetic Polyphenolic Derivative

The development of harmless substances to replace biocide-based coatings used to prevent or manage marine biofouling and its unwanted consequences is urgent. The formation of biofilms on submerged marine surfaces is one of the first steps in the marine biofouling process, which facilitates the further settlement of macrofoulers. Anti-biofilm properties of a synthetic polyphenolic compound, with previously described anti-settlement activity against macrofoulers, were explored in this work. In solution this new compound was able to prevent biofilm formation and reduce a pre-formed biofilm produced by the marine bacterium, Pseudoalteromonas tunicata. Then, this compound was applied to a marine coating and the formation of P. tunicata biofilms was assessed under hydrodynamic conditions to mimic the marine environment. For this purpose, polyurethane (PU)-based coating formulations containing 1 and 2 wt.% of the compound were prepared based on a prior developed methodology. The most effective formulation in reducing the biofilm cell number, biovolume, and thickness was the PU-based coating containing an aziridine-based crosslinker and 2 wt.% of the compound. To assess the marine ecotoxicity impact of this compound, its potential to disrupt endocrine processes was evaluated through the modulation of two nuclear receptors (NRs), peroxisome proliferator-activated receptor gamma (PPAR gamma), and pregnane X receptor (PXR). Transcriptional activation of the selected NRs upon exposure to the polyphenolic compound (10 mu M) was not observed, thus highlighting the eco-friendliness towards the addressed NRs of this new dual-acting anti-macro- and anti-microfouling agent towards the addressed NRs

Automated pathway curation and improving metabolic model reconstruction based on phylogenetic analysis of pathway conservation

ICSB 2017 - 18th International Conference on Systems BiologyMetabolic models generated by automated reconstruction pipelines are widely used for high-throughput prediction of microbial phenotypes. However, the generation of accurate in-silico phenotype predictions based solely on genomic data continues to be a challenge as metabolic models often require extensive gapfilling in order to produce biomass. As a result, the true physiological profile of an organism can be altered by the addition of non-native biochemical pathways or reactions during the gapfilling process. In this study, we constructed draft genome-scale metabolic models for ~1000 diverse set of reference microbial genomes currently available in GenBank, and we decomposed these models into a set of classical biochemical pathways. We then determine the extent to which each pathway is either consistently present or absent in each region of the phylogenetic tree, and we study the degree of conservation in the specific steps where gaps exist in each pathway across a phylogenetic neighborhood. Based on this analysis, we improved the reliability of our gapfilling algorithms, which in turn, improved the reliability of our models in predicting auxotrophy. This also resulted in improvements to the genome annotations underlying our models. We validated our improved auxotrophy predictions using growth condition data collected for a diverse set of organisms. Our improved gapfilling algorithm will be available for use within the DOE Knowledgebase (KBase) platform (https://kbase.us).info:eu-repo/semantics/publishedVersio

Monitoring Antibiotic Comsumption in the Surgery and Orthopaedics

A monitorização do consumo de antimicrobianos é um instrumento de interesse indiscutível e tem merecido uma atenção particular nos últimos anos, devido às crescentes preocupações com a emergência de estirpes microbianas multi-resistentes. Os objectivos do presente estudo consistiram, por um lado, na monitorização do consumo e na avaliação do impacto económico da prescrição hospitalar de antimicrobianos, em serviços de cirurgia e ortopedia. Por outro lado, pretendeu-se estudar e a relação indicação-prescrição terapêutica e profilática. Tendo presentes estes objectivos realizou-se um estudo-piloto longitudinal, com recolha de dados durante o mês de Maio de 2004, em seis Hospitais SA, incidindo numa amostra total de 1.122 doentes internados. Verificámos uma taxa de incidência de prescrição de 76,9%, com dispensa de 1.154 antimicrobianos, dos quais 71,2% se destinaram, em média, à profilaxia da infecção pós-cirúrgica, atestando a adesão geral à prática da profilaxia da infecção no local cirúrgico. O custo médio da antibioterapia foi mais elevado nos casos de “suspeita de infecção” (€9,09) ou “infecção declarada” (€8,74) e mais baixo quando utilizados para “profilaxia” (€5,67), facto relacionado com a menor duração média dos episódios de profilaxia. Os regimes de profilaxia utilizados apresentaram variações consideráveis entre os diferentes hospitais no que respeita ao tipo de antibiótico utilizado e uma duração média de 2,61 dias, com cerca de metade dos episódios de profilaxia prolongando-se por mais de 24 horas, sugerindo uma implementação insuficiente das actuais recomendações quanto ao tipo de fármaco a utilizar para esta prática, o que aponta para o necessidade duma avaliação da existência nas unidades hospitalares, de recomendações claras para a profilaxia da infecção do local cirúrgico, bem como da adesão dos clínicos a estas

New localities and lineages of the Atlas dwarf lizard Atlantolacerta andreanskyi identified using mitochondrial DNA markers

Atlantolacerta andreanskyi (Werner, 1929) is an endemic lizard from the High Atlas Mountains region of Morocco. A previous molecular assessment of this species using mitochondrial and nuclear DNA markers uncovered extensive genetic diversity with seven lineages indicative of a species complex. A morphological assessment of six of these lineages did not establish simple diagnostic features, and proposed these should be considered as a cryptic species, while highlighting the need for greater sampling across the range. In this study, we sampled 8 individuals from 5 previously unsampled localities and carried out genetic analyses to compare these populations to the known variation. Phylogenetic reconstruction based on mitochondrial DNA markers (12S rRNA and ND4) corroborates the previously described lineages and identified a new one. Interestingly, the two samples that account for this newly identified lineage have been collected from distinct localities – M’goun and Toumliline – that form a sister taxon to the population of Jbel Azourki