Microbiology laboratory

Microbiology in the field of food technology deals with the interactions between microorganisms and food. Beneficial microorganisms serve to produce and refine food. Harmful microorganisms, on the other hand, spoil food, shorten its shelf life and can trigger serious illnesses in consumers. In the micro- and biotechnological teaching and research laboratory, students learn all relevant basic microbiological knowledge and working techniques in the field of food microbiology and food hygiene.

In the microbiology laboratory, all important examination methods of microbiological food monitoring and operational hygiene can be carried out. High-quality equipment such as air samplers or a Biostat A fermenter are available for this purpose. Various photometric and imaging methods complement the analysis options. For practical experiments, the centre has its own strain collection with various bacteria, yeasts and moulds. In addition, biochemical structural analyses of food components can be carried out. Gas and liquid chromatographic analysis methods are available for this purpose. Cell cultivation techniques can be used to show how functional food components work. Up to 20 workstations are available for practical training.

In the practical courses, students apply the theoretical knowledge from the lectures in practice and deepen it. The topic in the 2nd semester is food microbiology. One focus is the examination and evaluation of food contamination. The students learn how to microscope bacteria, yeasts and moulds. They grow microorganisms and learn how and with what microorganisms can be propagated, how to identify the shape of bacteria by staining and how to determine the germ content in a food, e.g. raw milk.

Food hygiene is the main topic in the 3rd semester. The students learn about different microbiological examination methods, for example for ice cream and drinking water. The aim here is to look at the total bacterial count of food and its possible contamination with pathogens, such as salmonella and listeria, and to determine whether the respective food is fit for consumption according to the legal limits. Within the scope of the topic area of in-house inspections, students gain insights into the possibilities of checking food packaging, airborne germ content and in-house cleaning and disinfection.

Characterisation of active ingredients for functional foods

Food components such as polyphenols, peptides or sugar compounds are investigated for possible antimicrobial effects in order to create alternative preservation concepts. This is done with photometric analysis methods and microbiological culture techniques.

Formulation concepts for probiotic bacteria for foods

In order to introduce probiotic microorganisms into food in a safe, stable and physiologically active way, different granulation and encapsulation materials are developed. These include hydrocolloids or protein matrices. Then their influence on the biofunctionality and product stability of the food is tested. This is done with storage tests and artificial in vitro gut models.

Immunofunctional food components

In cooperation with the University Hospital Frankfurt am Main (Prof. Dr. R. Schubert), the influence of food components such as polyunsaturated fatty acids on the regulation of the immunological defence is being investigated, especially in relation to the development and evolution of chronic obstructive pulmonary diseases such as asthma.

The equipment in the microbiology laboratory is of high quality and extensive:

• Anaerobic workbench: This device offers the possibility of gassing microorganisms with a mixture of hydrogen, carbon dioxide and nitrogen so that they can grow in the absence of oxygen.
• Biostat A fermenter for cultivating bacteria
• Incubators for microorganisms and cell cultures
• Bioscreen C: This device can be used to study the growth of bacteria over a longer period of time. This works by measuring the optical density at regular intervals, e.g. every half hour at a temperature of 37 degrees. The growth values can be displayed as curves in Excel.
• Photometer: This device is also used to measure the optical density. It is used, for example, to have the same number of microorganisms in a nutrient medium (e.g. for the production of a certain type of beer).
• Gas chromatograph (GC) with FID for separating mixtures into individual chemical compounds.
• Äktaprime plus: Chromatography system for protein purification
• IDEXX Quanti Tray Sealer for water testing, independent of plates - individual boxes show by colour change how many bacteria are present
• PCR cycler: device that can independently perform the temperature cycles of a polymerase chain reaction (PCR)
• Air sampler
• ph-meter for measuring the ph-value
• Microscopes
• Microbiological safety cabinets
• Freezers: - 80 °C for microbiological strain collections and - 20 °C
• Refrigerators
• Centrifuges
• Water baths
• Autoclaves for sterilisation of culture media, Petri dishes etc.