Strain-specific behaviour of butyric acid producing clostridia under stress conditions

Clostridium spp. can enter cheese production through contamination of raw milk. This can lead to quality defects in the production of semi-hard and hard cheeses, as clostridia are responsible for incorrect fermentation during cheese ripening. This so-called late blowing defect is characterized by excessive eye formation, slits and cracks, and leads to an undesirable off-flavour due to the formation of organic acids. These defects lead to significant economic losses in cheese production, as such cheeses are no longer marketable. The bacterial species Clostridium tyrobutyricum is mainly associated with late blowing. However, this endospore-forming bacterium remains understudied. Interestingly, previous studies have shown a large phenotypic and genotypic variability between strains of this species. The aim of this project is to identify and characterise strain-specific differences in clostridia (especially C. tyrobutyricum). In particular, the response of this bacterium to different environmental conditions and the metabolic background of its growth behaviour will be investigated. The results should provide important basic knowledge for a better understanding of spoilage-causing clostridia. Knowledge of the germination and growth behaviour of this spoilage bacterium may ultimately be of practical relevance for dairy production and contribute to the prevention of cheese spoilage.