Bioconversion and Protective Cultures

Microbiological and molecular biological methods

• Traditional microbiological methods for the detection of different microorganism groups

• Various assays to determine the inhibitory effect of selected microorganisms (e.g. on mycelial growth, which results from the germination of mould spores)

• Identification using modern molecular biology methods (in-house and externally, qPCR, etc.)

• MALDI-TOF mass spectrometry (in collaboration with Agroscope)

• Biolog characterisation of substrate use in lactic acid bacteria (in collaboration with Agroscope)

• Clarification of QPS status (e.g. antibiotic resistance, virulence or production of biogenic amines)

Physicochemical methods

• HPLC UV/RID to identify sugars and organic acids, vitamins formed, etc.
• Verification and quantification of composition (proteins, fats, carbohydrates, micronutrients) and structure (consistency, elasticity, viscosity)
• Rheometry
• Selective photometric determination

Current projects

• Innosuisse “FermPlant” project: controlled fermentation of sauerkraut for improved sensory properties and enhanced nutritional value (collaboration with Agroscope and Schöni Finefood)
• Gebert Rüf (First Ventures) “Fermeat” project: assistance with the development of fermentation strategies (based on the use of moulds) for the production of plant-based alternatives to meat
• Innosuisse and internal HAFL “Molein” project: extraction and functionalisation of leaf protein from the horseradish tree (Moringa oleifera) for food applications
• “Wood&Field”: whey fermentation

Completed projects

• “FermPlant”: fermentation schemes for high-quality plant-based foods (internal HAFL project, HAFL call 2017-2020)
• Fermentation schemes for natural, in-situ enrichment of vitamin B12 in non-alcoholic, fermented, vegan beverages (internal HAFL project, food systems call 2018-2019)
• Sustainable, healthy and palatable alternatives to meat (internal HAFL project, food systems call 2018-2019)
• Swiss Food Research Project (2015): capturing the value of okara – a fibre-rich by-product of tofu processing
• “Rebels”: recycling of molasses (by-product of sugar manufacture)

Current projects

PlantProtect

The fungus Thielaviopsis (T.) basicola (syn. Chalara elegans) causes black root rot disease, which leads to huge losses of some crops in the field and in storage. The present project seeks to develop an alternative biopreservation method based on a protective culture consisting of lactic acid bacteria. The aim is to establish a resilient microbial system that prevents the development of black rot on carrots (as a model organism). The project involves close collaboration between BFH HAFL, Agroscope and the University of Fribourg; it is supported by the Swiss vegetable sector (Swisscofel, VSGP) and the Sur-la-Croix foundation.

ProBerry (Innosuisse project)

The main aim of this project is to investigate the potential use of lactic acid bacteria (LAB) in the development of protective cultures as an alternative strategy for preventing food spoilage. The project uses strawberries and their main spoilage agent Botrytis cinerea (a mould) as an example. The model serves as proof of concept for the further development of protective cultures for use with fresh or minimally processed fruit and vegetables. The results are expected to include an extended shelf life, a reduction in residues and environmental risks from pesticide use, and a reduction in food losses, thereby improving profitability throughout the food value chain. The ecological potential of useful microorganisms to protect strawberries is being tested in the laboratory, in greenhouses and in the field (pre- and post-harvest).

Publications

• Eugster, Elisabeth; Heine, Daniel; Sartori, Carlotta (2020). Unsichtbare Lebensgemeinschaften in fermentierten Lebensmitteln Hotspot (42), S. 18. Schweiz Akademie der Naturwissenschaften (SCNAT), Forum Biodiversität

Only in relation to the metabolism of lactic acid bacteria:

• Wenger, Alexander; Schmidt, Remo S.; Portmann, Reto; Roetschi, Alexandra; Eugster, Elisabeth; Weisskopf, Laure; Irmler, Stefan (2020). Identification of a species-specific aminotransferase in Pediococcus acidilactici capable of forming α-aminobutyrate AMB Express, 10(1) Springer 10.1186/s13568-020-01034-2
• Eugster, Elisabeth; Fuchsmann, Pascal; Schlichtherle-Cerny, Hedwig; Bütikofer, Ueli; Irmler, Stefan (2019). Formation of alanine, α-aminobutyrate, acetate, and 2-butanol during cheese ripening by Pediococcus acidilactici FAM18098 International Dairy Journal, 96, S. 21-28. Elsevier 10.1016/j.idairyj.2019.04.001
• Wüthrich, Daniel; Irmler, Stefan; Berthoud, Hélène; Guggenbühl, Barbara; Eugster, Elisabeth; Bruggmann, Rémy (2018). Conversion of Methionine to Cysteine in Lactobacillus paracasei Depends on the Highly Mobile cysK-ctl-cysE Gene Cluster Frontiers in Microbiology, 9 Frontiers 10.3389/fmicb.2018.02415
• Schmid, Michael; Muri, Jonathan; Melidis, Damianos; Varadarajan, Adithi R.; Somerville, Vincent; Wicki, Adrian; Moser, Aline; Bourqui, Marc; Wenzel, Claudia; Eugster, Elisabeth; Frey, Juerg E.; Irmler, Stefan; Ahrens, Christian H. (2018). Comparative Genomics of Completely Sequenced Lactobacillus helveticus Genomes Provides Insights into Strain-Specific Genes and Resolves Metagenomics Data Down to the Strain Level Frontiers in Microbiology, 9(63), S. 1-20. Frontiers Media 10.3389/fmicb.2018.00063
• Moser, Aline; Wüthrich, Daniel; Bruggmann, Rémy; Eugster, Elisabeth; Meile, Leo; Irmler, Stefan (2017). Amplicon Sequencing of the slpH Locus Permits Culture-Independent Strain Typing of Lactobacillus helveticus in Dairy Products Frontiers in Microbiology, 8(1380), S. 1-11. Frontiers Media 10.3389/fmicb.2017.01380
• Lüdin, Petra; Von Ah, Ueli; Rollier, Deborah; Roetschi, Alexandra; Eugster, Elisabeth (2016). Lactic Acid Bacteria as Markers for the Authentication of Swiss Cheeses CHIMIA International Journal for Chemistry, 70(5), S. 349-353. Schweizerische Chemische Gesellschaft 10.2533/chimia.2016.349