Production of 2,3-butanediol in Saccharomyces cerevisiae by in silico aided metabolic engineering

BACKGROUND: 2,3-Butanediol is a chemical compound of increasing interest due to its wide applications. It can be synthesized via mixed acid fermentation of pathogenic bacteria such as Enterobacter aerogenes and Klebsiella oxytoca. The non-pathogenic Saccharomyces cerevisiae possesses three different 2,3-butanediol biosynthetic pathways, but produces minute amount of 2,3-butanediol. Hence, we attempted to engineer S. cerevisiae strain to enhance 2,3-butanediol production. RESULTS: We first identified gene deletion strategy by performing in silico genome-scale metabolic analysis. Based on the best in silico strategy, in which disruption of alcohol dehydrogenase (ADH) pathway is required, we then constructed gene deletion mutant strains and performed batch cultivation of the strains. Deletion of three ADH genes, ADH1, ADH3 and ADH5, increased 2,3-butanediol production by 55-fold under microaerobic condition. However, overproduction of glycerol was observed in this triple deletion strain. Additional rational design to reduce glycerol production by GPD2 deletion altered the carbon fluxes back to ethanol and significantly reduced 2,3-butanediol production. Deletion of ALD6 reduced acetate production in strains lacking major ADH isozymes, but it did not favor 2,3-butanediol production. Finally, we introduced 2,3-butanediol biosynthetic pathway from Bacillus subtilis and E. aerogenes to the engineered strain and successfully increased titer and yield. Highest 2,3-butanediol titer (2.29 g·l(-1)) and yield (0.113 g·g(-1)) were achieved by Δadh1 Δadh3 Δadh5 strain under anaerobic condition. CONCLUSIONS: With the aid of in silico metabolic engineering, we have successfully designed and constructed S. cerevisiae strains with improved 2,3-butanediol production

Alleviation of carbon catabolite repression in Enterobacter aerogenes for efficient utilization of sugarcane molasses for 2,3-butanediol production

Table S3. Comparison of fed-batch fermentation with EMY-01, EMY-68, EMY-70S, and EMY-70SP using sugarcane molasses

Mechanisms of Cross-protection by Influenza Virus M2-based Vaccines

Current influenza virus vaccines are based on strain-specific surface glycoprotein hemagglutinin (HA) antigens and effective only when the predicted vaccine strains and circulating viruses are well-matched. The current strategy of influenza vaccination does not prevent the pandemic outbreaks and protection efficacy is reduced or ineffective if mutant strains emerge. It is of high priority to develop effective vaccines and vaccination strategies conferring a broad range of cross protection. The extracellular domain of M2 (M2e) is highly conserved among human influenza A viruses and has been utilized to develop new vaccines inducing cross protection against different subtypes of influenza A virus. However, immune mechanisms of cross protection by M2e-based vaccines still remain to be fully elucidated. Here, we review immune correlates and mechanisms conferring cross protection by M2e-based vaccines. Molecular and cellular immune components that are known to be involved in M2 immune-mediated protection include antibodies, B cells, T cells, alveolar macrophages, Fc receptors, complements, and natural killer cells. Better understanding of protective mechanisms by immune responses induced by M2e vaccination will help facilitate development of broadly cross protective vaccines against influenza A virus

Porous organic polymers as ionomers for high-performance alkaline membrane water electrolysis

Producción CientíficaThe pressing nature of the climate emergency, coupled with the depletion of fossil fuel reserves, underscores the critical need for renewable energy alternatives, in which green hydrogen is recognized as a viable, environmentally sustainable energy option that has gained substantial interest in recent years.Unlike methods dependent on petroleum processing, green hydrogen production revolves around water splitting through electrolysis, powered by electricity generated from solar power or other renewable sources, and it has been suggested as a pathway to achieve carbon neutrality within the coming decades. Traditional alkaline water electrolyzers typically employ highly concentrated alkaline solutions, presenting drawbacks such as accelerated corrosion, and vulnerability to ambient CO2, leading to electrode blockages and reduced conductivity. In response to these challenges, polymer electrolyte water electrolysis systems like proton exchange membrane water electrolyzers and AEMWEs have emerged as prominent solutions. The main component of the AEMWE system is the membrane electrode assembly (MEA), consisting of an AEM, ionomers, and catalysts. The AEM acts as a barrier, separating the anode and cathode electrodes to prevent gas crossover, whereas the ionomers act as binders, linking or stabilizing catalyst particles while facilitating ion transport. Over the past decades, significant advancements have been achieved in highperformance AEM development. However, the significance of ionomer design often goes unnoticed. Typically, ionomers are chosen with identical or similar structures as AEMs, yet the different working conditions of AEMs and ionomers require different properties. Ionomers must possess high water and gas permeability, electrochemical stability, and low catalyst adsorption ability.Spain’s Agencia Estatal de Investigación [Projects PID2019-109403RB-C22 (I/FEDER, UE), PID2019-109403RB-C21 and PID2020-118547GB-I00 (AEI/FEDER, UE)], by the Spanish Junta de Castilla y León (VA224P2). This work was also supported by the Nano·Materials Technology Development program (RS-2023-00235295) through the (NRF) funded by the Ministry of Science and ICT of South Korea

An Overview of Biomaterials in Periodontology and Implant Dentistry

Material is a crucial factor for the restoration of the tooth or periodontal structure in dentistry. Various biomaterials have been developed and clinically applied for improved periodontal tissue regeneration and osseointegration, especially in periodontology and dental implantology. Furthermore, the biomimetic approach has been the subject of active research in recent years. In this review, the most widely studied biomaterials (bone graft material, barrier membrane, and growth or differentiation factors) and biomimetic approaches to obtain optimal tissue regeneration by making the environment almost similar to that of the extracellular matrix are discussed and specifically highlighted

Respiratory Syncytial Virus-Like Nanoparticle Vaccination Induces Long-Term Protection Without Pulmonary Disease by Modulating Cytokines and T-cells Partially Through Alveolar Macrophages

The mechanisms of protection against respiratory syncytial virus (RSV) are poorly understood. Virus-like nanoparticles expressing RSV glycoproteins (eg, a combination of fusion and glycoprotein virus-like nanoparticles [FG VLPs]) have been suggested to be a promising RSV vaccine candidate. To understand the roles of alveolar macrophages (AMs) in inducing long-term protection, mice that were 12 months earlier vaccinated with formalin-inactivated RSV (FI-RSV) or FG VLPs were treated with clodronate liposome prior to RSV infection. FI-RSV immune mice with clodronate liposome treatment showed increases in eosinophils, plasmacytoid dendritic cells, interleukin (IL)-4+ T-cell infiltration, proinflammatory cytokines, chemokines, and, in particular, mucus production upon RSV infection. In contrast to FI-RSV immune mice with severe pulmonary histopathology, FG VLP immune mice showed no overt sign of histopathology and significantly lower levels of eosinophils, T-cell infiltration, and inflammatory cytokines, but higher levels of interferon-γ, which are correlated with protection against RSV disease. FG VLP immune mice with depletion of AMs showed increases in inflammatory cytokines and chemokines, as well as eosinophils. The results in this study suggest that FG nanoparticle vaccination induces long-term protection against RSV and that AMs play a role in the RSV protection by modulating eosinophilia, mucus production, inflammatory cytokines, and T-cell infiltration

Input of terrestrial organic matter linked to deglaciation increased mercury transport to the Svalbard fjords

Deglaciation has accelerated the transport of minerals as well as modern and ancient organic matter from land to fjord sediments in Spitsbergen, Svalbard, in the European Arctic Ocean. Consequently, such sediments may contain significant levels of total mercury (THg) bound to terrestrial organic matter. The present study compared THg contents in surface sediments from three fjord settings in Spitsbergen: Hornsund in the southern Spitsbergen, which has high annual volume of loss glacier and receives sediment from multiple tidewater glaciers, Dicksonfjorden in the central Spitsbergen, which receives sediment from glacifluvial rivers, and Wijdefjorden in the northern Spitsbergen, which receive sediments from a mixture of tidewater glaciers and glacifluvial rivers. Our results showed that the THg (52 +/- 15 ng g(-1)) bound to organic matter (OM) was the highest in the Hornsund surface sediments, where the glacier loss (0.44 km(3) yr(-1)) and organic carbon accumulation rates (9.3 similar to 49.4 g m(-2) yr(-1)) were elevated compared to other fjords. Furthermore, the delta C-13 (-27 similar to -24 parts per thousand) and delta S-34 values (-10 similar to 15 parts per thousand) of OM indicated that most of OM were originated from terrestrial sources. Thus, the temperature-driven glacial melting could release more OM originating from the meltwater or terrestrial materials, which are available for THg binding in the European Arctic fjord ecosystems.11Ysciescopu