Glycosylation can influence the physicochemical and biological properties of organic molecules such as anti-oxidants, antibiotics, and sweeteners. An industrially relevant example is the glycosylation of steviol glycosides, sweet compounds extracted from the Stevia plant, resulting – if done right – in the removal of their undesired bitterness. The chemical synthesis of glycosides is characterized by multistep routes generating lots of waste. One-step enzymatic glycosylation, in particular by using glucansucrase enzymes, offers an alternative, eco-friendly approach.

The first part of this thesis was focused on the improvement of glucansucrases as glycosylation biocatalysts in general by reaction -and enzyme engineering strategies. The obtained knowledge was subsequently used for the glycosylation of steviol glycosides, with the ultimate goal of improving their sensory properties. After selecting the appropriate enzyme mutant, the reaction conditions were optimized and an efficient downstream processing was developed. The sensory properties were evaluated by a trained taste panel, revealing that the glycosylated steviol glycosides possess improved sensory properties. As the developed technology showed excellent commercial potential, a cost analysis of the proposed process was performed, pointing out opportunities for future process improvement.