Alexander Mathys


Last Name

Mathys

First Name

Alexander

ORCID

0000-0003-1633-848X

Organisational unit

09571 - Mathys, Alexander / Mathys, Alexander

Search Results

Publications1 - 10 of 573
  • Lower levels of lipoprotein YhcN likely contribute to B. subtilis spores high pressure superdormancy
    Item type: Other Conference Item
    Delbrück, Alessia I.; Nanni, Paolo; Heydenreich, Rosa; et al. (2021)
  • Using nutrient profiling algorithms to compare nutritionally-invested environmental impacts of cow ’s milk and plant-based beverages
    Item type: Other Conference Item
    Green, Ashley; Nemecek, Thomas; Mathys, Alexander (2022)
    Proceedings of the 13th International Conference on Life Cycle Assessment of Food (LCA Foods 2022)
  • Color loss kinetics of the functional microalgae protein phycocyanin under short time micro processing
    Item type: Other Conference Item
    Böcker, Lukas; Surber, Jakob; Leeb, Elena; et al. (2017)
    World Food System Center 2017 Research Symposium: Program and Abstracts
  • Amino acid profile and protein bioaccessibility of two Galdieria sulphuraria strains cultivated autotrophically and mixotrophically in pilot-scale photobioreactors
    Item type: Journal Article
    Canelli, Greta; Abiusi, Fabian; Vidal Garcia, Albert; et al. (2023)
    Innovative Food Science & Emerging Technologies
    Galdieria sulphuraria is considered one of the most promising microalgae for food applications. In this study, we compared two strains of G. sulphuraria cultivated autotrophically and mixotrophically over 35 days in pilot-scale photobioreactors under nonsterile conditions. The low pH (<1.9) used for cultivation successfully prevented microbial contamination. The two strains had similar autotrophic and mixotrophic biomass productivities, the latter being 2.3 times higher than autotrophic productivity. Comparing the two strains, G. sulphuraria SAG 108.79 and ACUF 064 had 51% and 64% (w/w) protein and 4% and 9% (w/w) C-phycocyanin content, respectively. Interestingly, G. sulphuraria SAG 108.79 showed a protein bioaccessibility of 62%, in line with other microalgal species, whereas G. sulphuraria ACUF 064 had a protein bioaccessibility of only 14%. No differences in the amino acid profile were found between the two strains or between trophic modes. Stable and well-balanced protein profiles are encouraging results for future applications of this species.
  • Revisiting bacterial spore germination in the presence of peptidoglycan fragments
    Item type: Journal Article
    Heydenreich, Rosa; Nacita, Juliana; Lin, Chia-wei; et al. (2025)
    Journal of Bacteriology
    Bacterial spores of Bacillus species are metabolically inert cell types formed in response to nutrient starvation. Spores must undergo the process of germination to resume vegetative growth. This process is stimulated by the interaction of various nutrient molecules with specialized clusters of membrane-localized germinant receptors (GRs) present within spores. A second route to spore germination involving the stimulation of the PrkC Ser/Thr kinase by soluble peptidoglycan fragments was proposed in 2008 and has been subject to much less scrutiny. The current study examined the germinative response of spores of Bacillus subtilis, Bacillus cereus, and Bacillus megaterium when incubated in the presence of complex mixtures of peptidoglycan fragments or purified peptidoglycan fragments previously identified as germinants. The spore suspensions did not show any appreciable germination, as determined by fluorometric dipicolinic acid release, flow cytometry, or microscopy. However, the purified peptidoglycan fragments displayed a stimulatory effect on germination triggered by amino acids and nucleosides with spore GRs. In contrast, GR-mediated germination was inhibited to varying degrees by unidentified components of the complex peptidoglycan fragment mixtures derived from enzymatic digests of B. subtilis vegetative sacculi. Collectively, our results indicate that soluble peptidoglycan fragments cannot initiate spore germination but may influence germination via mechanisms that have yet to be established.
  • Methodological choices and nutritional value in LCAs of waste-to-protein pathways
    Item type: Conference Poster
    Siegrist, Armin; Green, Ashley; Gold, Moritz; et al. (2024)
    1. Introduction Environmental sustainability and nutrient conversion efficiency of bioconversion technologies applied in waste-to-protein pathways is relevant from an early development stage to avoid undesired trade-offs when aiming to replace conventional protein sources. 2. Methods The Web of Science and Scopus databases were searched for keywords related to sustainability, feed conversion, residual biomass (RB), food or feed applications, and protein. Articles published in 2018 or later containing at least one keyword from each category were selected (n = 1441) and screened for quantitative information of interest. The final selection yielded 22 LCA studies and 31 articles related to protein quantity or quality. 3. Results and discussion All but one study focused on feed rather than food applications and research is mainly focused on black soldier fly (BSF). The range of reported impacts for all types of bioconversion technologies was found to span multiple orders of magnitude. However, comparing environmental impacts from different studies is difficult because of divergent methodological approaches, e.g. functional units, system boundary, method of impact allocation, and consideration of RB burdens. This highlights the strong need for methodological harmonization and transparency when dealing with circular multi-output systems. A wide range of dry-matter protein contents was found, e.g. microalgae (13–53%), fungi (17–70%), and insects (20–64%) grown on RB. A major source of uncertainty is the applied nitrogen-to-protein conversion factor, for example, it could vary between 4.76 and 6.25 for BSF, which results in protein contents differing by 25%. Among bioconversion technologies, amino acid (AA) profiles were predominantly found for BSF larvae produced as feed and related to optimal dietary profiles for broiler chickens and fish species. 4. Conclusions The large variability of RB and bioconversion technologies necessitates harmonized methodological alignment to produce comparable results with integration of nutritional factors.
  • COVID-19 pandemic lessons for agri-food systems innovation
    Item type: Other Journal Item
    Barrett, Christopher B.; Fanzo, Jessica; Herrero, Mario; et al. (2021)
    Environmental Research Letters
  • Tackling Food System Challenges by Emerging Technologies and Novel Protein Sources
    Item type: Other Conference Item
    Mathys, Alexander (2019)
  • High-pressure processing for mild bacterial spore control in industry and research
    Item type: Other Conference Item
    Heydenreich, Rosa; Delbrück, Alessia I.; Trunet, Clément; et al. (2024)
    GMPC Thesis & Opinions Platform
    High-pressure (HP) processing can enable mild bacterial spore control. Established sterilization processes, such as thermal treatment, are not universally applicable for heat sensitive products. The industry thus requires processes that effectively inactivate spores while preserving sensitive components, such as vitamins, the food color, or the food texture. This is in line with the consumer demand for healthy, minimally processed products. Current industrial non-thermal HP processing at 400–600 MPa and temperatures commonly ≤25°C can increase the shelf-life o heat sensitive products. However, bacterial spores are not inactivated and must be controlled by the product formulation or storage conditions. Inactivation of dormant spores is achieved through a combination of HP with high temperatures (>90°C), which is emerging in industry. To inactivate spores by HP while keeping the thermal input as low as possible, HP processing at a moderate temperature (<90°C) is under research. HP and moderate temperatures can trigger germination, which makes the spores sensitive to mild inactivation by HP or heat. The limitation of an HP germination inactivation strategy is that not all spores could be triggered to germinate so far. Hence, our study evaluated strategies to increase the HP germination efficacy of Bacillus spores. HP treatments (150 MPa, 37°C, 5 min or 550 MPa, 60°C, 2.5 min) were combined with other potential germination-promoting factors, such as nutrient germinants, nisin or incubation at 37°C and atmospheric pressure. The most effective combination led to -8.0±0.1 or -2.0±0.1 log10 units (n=3) germinated Bacillus subtilis or Bacillus amyloliquefaciens spores, respectively, as analyzed by plate count. Complete germination could be achieved for neither species. In conclusion, HP treatment at moderate temperature seems only to ensure effective mild bacterial spore inactivation in combination with additional germination promotors or preservation strategies. Our study provides future research directions and contributes to the efficient development of mild spore inactivation strategies.
  • Tackling Global Food System Challenges by Sustainable Processing Principles
    Item type: Presentation
    Mathys, Alexander (2018)
Publications1 - 10 of 573