Schwan, B. | Search bioRxiv

bioRxiv2023

The quest for improved biohydrogen formation: are heat shocks the solution?

BackgroundThe integration of anaerobic digestion into bio-based industries can create synergies, which help to make anaerobic digestion self-sustaining. Two-stage digesters with separate acidification stages allow to produce green hydrogen and short-chain fatty acids, which are promising industrial products. Heat shocks can be used to foster the production of these products. However, the practical applicability is oft not addressed sufficiently. The here presented work aims to close this gap. MethodsBatch experiments were conducted in 5 litre double-walled tank reactors incubated at 37 {degrees}C. Short microwave heat shocks of 25 min duration and exposure times of 5 - 10 min at 80 {degrees}C were performed and compared to oven heat shocks. Pairwise experimental group differences for gas production and chemical parameters were determined using ANOVA and post-hoc tests. High-throughput 16S rRNA gene amplicon sequencing was performed to analyse taxonomic profiles. ResultsHeat shocking the entire seed sludge, the highest hydrogen productivity was observed at a substrate load of 50 g/l with 1.09 mol H2/mol hexose. With 1.01 mol H2/mol hexose, microwave assisted treatment was not significantly different from oven-based treatments. The study emphasised the better repeatability of heat shocks with microwave-assisted experiments, showing low variation coefficients averaging 29 %. Microwave pre-treatment indicates a high predictability and a stronger microbiome shift to Clostridia than the oven. The pre-treatment of heat shocks supported the formation of butyric acid up to 10.8 g/l in average and a peak of 24.01 g/l at a butyric/acetic acid ratio of 2.0. ConclusionResults show the suitability to heat shock the entire seed sludge rather than just a small inoculum, which makes the process more relevant for industrial application. A microwave-based treatment has proven to be a promising alternative to oven-based treatments, which ultimately might facilitate the implementation into industrial systems. The approach becomes economically sustainable with high-temperature heat pumps with a coefficient of performance (COP) of 4.3.

bioengineering↗

bioRxiv2020

Identification and characterization of CD4+ T cell epitopes after Shingrix vaccination.

Infections with varicella zoster virus (VZV), a member of the Herpesviridae family, are associated with a range of clinical manifestations. Primary infection with VZV causes chicken pox, and due to the viruss capacity to remain latent in neurons, it can reactivate later in life causing herpes zoster (HZ), also known as shingles. Two different vaccines have been developed to prevent HZ, one based on a live attenuated VZV strain (Zostavax) and the other on adjuvanted gE recombinant protein (Shingrix). While Zostavax efficacy wanes with age, Shingrix protection retains its efficacy in elderly subjects (80 years of age and beyond). In this context, it is of much interest to understand if there is a role for T cell immunity in differential clinical outcome, and if there is a correlate of protection between T cell immunity and Shingrix efficacy. In this study, we characterized Shingrix specific ex vivo CD4 T cell responses in the context of natural exposure and HZ vaccination using pools of predicted epitopes. We show that T cell reactivity following natural infection and Zostavax vaccination dominantly targets non-structural proteins (NS), while Shingrix vaccination redirects dominant reactivity to target gE. We mapped the gE-specific responses following Shingrix vaccination to 89 different gE epitopes, 34 of which accounted for 80% of the response. Using antigen presentation assays and single HLA molecule transfected lines, we experimentally determined HLA restrictions for 94 different donor/peptide combinations. Finally, we used our results as a training set to assess strategies to predict restrictions based on measured or predicted HLA binding and the corresponding HLA types of responding subjects. ImportanceUnderstanding the T cell profile associated with the protection observed in elderly vaccinees following Shingrix vaccination is relevant to the general definition of correlates of vaccine efficacy. Our study enables these future studies by clarifying patterns of immunodominance associated with Shingrix vaccination, as opposed to natural infection or Zostavax vaccination. Identification of epitopes recognized by Shingrix-induced CD4 T cells and their associated HLA restrictions enables the generation of tetrameric staining reagents and, more broadly, the capability to characterize specificity, magnitude and phenotype of VZV specific T cells.

immunology↗