Towards valorization of pectin-rich agro-industrial residues: Engineering of Saccharomyces cerevisiae for co-fermentation of d-galacturonic acid and glycerol.

Pectin-rich plant biomass residues represent underutilized feedstocks for industrial biotechnology. The conversion of the oxidized monomer d-galacturonic acid (d-GalUA) to highly reduced fermentation products such as alcohols is impossible due to the lack of electrons. The reduced compound glycerol has therefore been considered an optimal co-substrate, and a cell factory able to efficiently co-ferment these two carbon sources is in demand. Here, we inserted the fungal d-GalUA pathway in a strain of the yeast S. cerevisiae previously equipped with an NAD-dependent glycerol catabolic pathway. The constructed strain was able to consume d-GalUA with the highest reported maximum specific rate of 0.23 g gCDW-1 h-1 in synthetic minimal medium when glycerol was added. By means of a 13C isotope-labelling analysis, carbon from both substrates was shown to end up in pyruvate. The study delivers the proof of concept for a co-fermentation of the two 'respiratory' carbon sources to ethanol and demonstrates a fast and complete consumption of d-GalUA in crude sugar beet pulp hydrolysate under aerobic conditions. The future challenge will be to achieve co-fermentation under industrial, quasi-anaerobic conditions.

YEASTRACT+: a portal for cross-species comparative genomics of transcription regulation in yeasts.

The YEASTRACT+ information system (http://YEASTRACT-PLUS.org/) is a wide-scope tool for the analysis and prediction of transcription regulatory associations at the gene and genomic levels in yeasts of biotechnological or human health relevance. YEASTRACT+ is a new portal that integrates the previously existing YEASTRACT (http://www.yeastract.com/) and PathoYeastract (http://pathoyeastract.org/) databases and introduces the NCYeastract (Non-Conventional Yeastract) database (http://ncyeastract.org/), focused on the so-called non-conventional yeasts. The information in the YEASTRACT database, focused on Saccharomyces cerevisiae, was updated. PathoYeastract was extended to include two additional pathogenic yeast species: Candida parapsilosis and Candida tropicalis. Furthermore, the NCYeastract database was created, including five biotechnologically relevant yeast species: Zygosaccharomyces baillii, Kluyveromyces lactis, Kluyveromyces marxianus, Yarrowia lipolytica and Komagataella phaffii. The YEASTRACT+ portal gathers 289 706 unique documented regulatory associations between transcription factors (TF) and target genes and 420 DNA binding sites, considering 247 TFs from 10 yeast species. YEASTRACT+ continues to make available tools for the prediction of the TFs involved in the regulation of gene/genomic expression. In this release, these tools were upgraded to enable predictions based on orthologous regulatory associations described for other yeast species, including two new tools for cross-species transcription regulation comparison, based on multi-species promoter and TF regulatory network analyses.

The mediating role of tolerance for psychological pain in the relationship of childhood trauma to suicidal ideation in individuals with a substance use disorder.

OBJECTIVES: The association between childhood trauma and suicidal ideation has been well documented in several populations, including individuals with a substance use disorder (SUD). However, a gap still exists in the literature regarding the mechanisms by which childhood trauma later impacts suicide risk. This cross-sectional study tested the effect of childhood trauma on suicidal ideation, as well as the mediating effect of tolerance for psychological pain (managing the pain and enduring the pain) in that relationship, controlling for the effect of depressive symptoms, in individuals with a SUD. METHODS: A sample of 102 adults with a SUD participated in the study. Path analysis by structural equation modelling tested a mediation model. RESULTS: Depressive symptoms and lower levels of managing the pain were found to fully mediate the association between childhood trauma and suicidal ideation. CONCLUSIONS: Our results suggest that depressive symptoms and a lack of ability to manage psychological pain contribute towards explaining why traumatic childhood experiences may result in suicidal cognitions in individuals with SUDs. Moreover, they have relevant implications for prevention and clinical interventions regarding suicidal ideation in this population. PRACTITIONER POINTS: Childhood trauma relates to suicidal ideation in individuals with a substance use disorder. Depressive symptoms contribute towards explaining why traumatic childhood experiences may result in suicidal cognitions. A lack of ability to manage psychological pain also contributes towards explaining this relationship. The obtained results have relevant implications for the prevention of and clinical intervention for suicidal ideation in SUD individuals.

Valorisation of pectin-rich agro-industrial residues by yeasts: potential and challenges.

Pectin-rich agro-industrial residues are feedstocks with potential for sustainable biorefineries. They are generated in high amounts worldwide from the industrial processing of fruits and vegetables. The challenges posed to the industrial implementation of efficient bioprocesses are however manyfold and thoroughly discussed in this review paper, mainly at the biological level. The most important yeast cell factory platform for advanced biorefineries is currently Saccharomyces cerevisiae, but this yeast species cannot naturally catabolise the main sugars present in pectin-rich agro-industrial residues hydrolysates, in particular D-galacturonic acid and L-arabinose. However, there are non-Saccharomyces species (non-conventional yeasts) considered advantageous alternatives whenever they can express highly interesting metabolic pathways, natively assimilate a wider range of carbon sources or exhibit higher tolerance to relevant bioprocess-related stresses. For this reason, the interest in non-conventional yeasts for biomass-based biorefineries is gaining momentum. This review paper focuses on the valorisation of pectin-rich residues by exploring the potential of yeasts that exhibit vast metabolic versatility for the efficient use of the carbon substrates present in their hydrolysates and high robustness to cope with the multiple stresses encountered. The major challenges and the progresses made related with the isolation, selection, sugar catabolism, metabolic engineering and use of non-conventional yeasts and S. cerevisiae-derived strains for the bioconversion of pectin-rich residue hydrolysates are discussed. The reported examples of value-added products synthesised by different yeasts using pectin-rich residues are reviewed. Key Points • Review of the challenges and progresses made on the bioconversion of pectin-rich residues by yeasts. • Catabolic pathways for the main carbon sources present in pectin-rich residues hydrolysates. • Multiple stresses with potential to affect bioconversion productivity. • Yeast metabolic engineering to improve pectin-rich residues bioconversion. Graphical abstract.

Evaluating the Electromagnetic Shielding of Continuous Carbon Fiber Parts Produced by Additive Manufacturing.

Electronic devices are sensitive to electromagnetic (EM) emissions, and require electromagnetic shielding protection to ensure good operation, and prevent noise, malfunctioning, or even burning. To ensure protection, it is important to develop suitable material and design solutions for electronic enclosures. Most common enclosures are made with metal alloys using traditional manufacturing methods. However, using thermoplastic composites combined with additive manufacturing (AM) technologies emerges as an alternative that enables the fabrication of complex parts that are lightweight, consolidated, and oxidation- and corrosion-resistant. In this research, an AM technique based on material extrusion was used to print 2 mm-thick specimens with a multi-material made of micro-carbon fiber (CF)-filled polyamide that was reinforced at specific layers using continuous carbon fibers stacked with a 90° rotation to each other. The specimens' electromagnetic shielding effectiveness (EMSE) was evaluated in the frequency band of 0.03-3 GHz using the coaxial transmission line method. Depending on the number of CF layers, the EM shielding obtained can be up to 70 dB, with a specific shielding up to 60 dB.cm3/g, predominantly by the absorption mechanism, being 22 times higher than without the CF layers. These findings promote this innovative approach to lightweight customizable solutions for EM shielding applications.

Results from Two Countries on How Thwarted Interpersonal Needs Contribute to Understanding Self-Harm.

Self-harming behavior (SHB) represents an important public health issue and is one of the most critical predictors of completed death by suicide. The current study evaluated the incremental contribution of the Interpersonal Theory of Suicide constructs of thwarted belongingness and perceived burdensomeness for the prediction of SHB beyond that associated with having a psychiatric diagnosis. Community adults from two different countries included a Portuguese sample of 414 adults, aged between 18 and 65 years (M = 45.09, SD = 13.11), and predominantly female (79%), and an American sample of 290 adults (198 men, 91 women, 1 unreported) with a mean age of 37.76 years (SD = 10.84) ranging from 20 to 71, who participated online. Results demonstrated mediation effects for perceived burdensomeness in the association of thwarted belongingness with SHB, partial mediation in the Portuguese sample and full mediation in the American sample. Findings also indicated that the interaction between thwarted belongingness and perceived burdensomeness failed to make a statistically significant contribution to the prediction of SHB. The results are discussed within the Interpersonal Theory of Suicide and its relevance for clinical practice.

The Identification of Genetic Determinants of Methanol Tolerance in Yeast Suggests Differences in Methanol and Ethanol Toxicity Mechanisms and Candidates for Improved Methanol Tolerance Engineering.

Methanol is a promising feedstock for metabolically competent yeast strains-based biorefineries. However, methanol toxicity can limit the productivity of these bioprocesses. Therefore, the identification of genes whose expression is required for maximum methanol tolerance is important for mechanistic insights and rational genomic manipulation to obtain more robust methylotrophic yeast strains. The present chemogenomic analysis was performed with this objective based on the screening of the Euroscarf Saccharomyces cerevisiae haploid deletion mutant collection to search for susceptibility phenotypes in YPD medium supplemented with 8% (v/v) methanol, at 35 °C, compared with an equivalent ethanol concentration (5.5% (v/v)). Around 400 methanol tolerance determinants were identified, 81 showing a marked phenotype. The clustering of the identified tolerance genes indicates an enrichment of functional categories in the methanol dataset not enriched in the ethanol dataset, such as chromatin remodeling, DNA repair and fatty acid biosynthesis. Several genes involved in DNA repair (eight RAD genes), identified as specific for methanol toxicity, were previously reported as tolerance determinants for formaldehyde, a methanol detoxification pathway intermediate. This study provides new valuable information on genes and potential regulatory networks involved in overcoming methanol toxicity. This knowledge is an important starting point for the improvement of methanol tolerance in yeasts capable of catabolizing and copying with methanol concentrations present in promising bioeconomy feedstocks, including industrial residues.

Complete Utilization of the Major Carbon Sources Present in Sugar Beet Pulp Hydrolysates by the Oleaginous Red Yeasts Rhodotorula toruloides and R. mucilaginosa.

Agro-industrial residues are low-cost carbon sources (C-sources) for microbial growth and production of value-added bioproducts. Among the agro-industrial residues available, those rich in pectin are generated in high amounts worldwide from the sugar industry or the industrial processing of fruits and vegetables. Sugar beet pulp (SBP) hydrolysates contain predominantly the neutral sugars d-glucose, l-arabinose and d-galactose, and the acidic sugar d-galacturonic acid. Acetic acid is also present at significant concentrations since the d-galacturonic acid residues are acetylated. In this study, we have examined and optimized the performance of a Rhodotorula mucilaginosa strain, isolated from SBP and identified at the molecular level during this work. This study was extended to another oleaginous red yeast species, R. toruloides, envisaging the full utilization of the C-sources from SBP hydrolysate (at pH 5.0). The dual role of acetic acid as a carbon and energy source and as a growth and metabolism inhibitor was examined. Acetic acid prevented the catabolism of d-galacturonic acid and l-arabinose after the complete use of the other C-sources. However, d-glucose and acetic acid were simultaneously and efficiently metabolized, followed by d-galactose. SBP hydrolysate supplementation with amino acids was crucial to allow d-galacturonic acid and l-arabinose catabolism. SBP valorization through the production of lipids and carotenoids by Rhodotorula strains, supported by complete catabolism of the major C-sources present, looks promising for industrial implementation.

MDR-1 C3435T polymorphism may affect blood pressure in resistant hypertensive patients independently of its effects on aldosterone release.

Aldosterone increases plasma volume and may be involved with resistant hypertension. P-glycoprotein is a transporter involved in the distribution and disposition of aldosterone, and is encoded by the MDR-1 gene. MDR-1 has functional polymorphisms that may affect P-glycoprotein expression. We hypothesized that the C(3435)T polymorphism in MDR-1 could be associated with resistant hypertension and with changes in hypertension-related parameters. We studied 105 healthy volunteers, 137 hypertensive patients responsive to treatment, and 83 resistant hypertensive patients. While we found no association of C(3435)T genotypes with resistance to treatment (p = 0.31), C allele was associated with hypertension (p = 0.03). Furthermore, the CC genotype was associated with higher systolic blood pressure (p < 0.01 for both daytime and nighttime, respectively) and diastolic blood pressure (p < 0.01 for both daytime and nighttime, respectively). This effect was probably independent of aldosterone, as we found no differences in aldosterone plasma levels, nor in pulse wave velocity (PVW) between the genotypes groups (p = 0.77 and p = 0.48, respectively). Our results show an association of C(3435)T with hypertension and with blood pressure levels in resistant hypertensive subjects.