Vassle, från miljöproblem till mervärdesprodukt via Candida intermedia?
Examensarbete på kandidatnivå
Gold Rodal, Iris
In the endeavor of making the dairy industry more environmentally sustainable, a resource with potential is cheese whey, a high nutrient and low monetary valued byproduct of cheese manufacturing. This study explores the potential for the utilization of cheese whey as a nutrient source for microbial cultivation of the yeast Candida intermedia. The aim is to optimize batch growth conditions for C. intermedia with regard to maximization of the yeast biomass titer, by means of experimental design. Employing synthetic cheese whey of varying composition as culture media, factors related to growth conditions were screened against the response in yeast concentration. This was done using a De nitive Screening Design as experimental setup. The most in uential factors, lactose and vitamin concentrations as well as temperature, were then optimized by response surface methodology applying a Central Composite Orthogonal Design. After 72 h of growth under the predicted optimal conditions, a 12% higher biomass titer was attained in comparison to the initially proposed growth conditions. The recorded speci c growth rates were similar. However, the yeast biomass yield for the optimized growth conditions were lower than for the original. In conclusion, these results show the great potential of combining experimental design and wet lab yeast cultivations for optimizing yeast biomass production. The project has resulted in an increased understanding of factors in uencing C. intermedia's capacity to convert nutrients in whey to yeast biomass and is thereby one step towards a future industrial implementation.