In the European chemical industry, there is a strong drive to shift from fossil to renewable resources in the pursuit of sustainability. Sophorolipids, a class of biosurfactants, are interesting renewable resources, since they combine a complex structure with divergent biological and physico-chemical properties. The microbially produced lactonic sophorolipids were used for the production of a broad range of innovative sophorolipid amines 1 and sophorolipid quaternary ammonium salts 2. These sophorolipid quaternary ammonium salts were evaluated for their antimicrobial activity against Gram-negative and Gram-positive bacterial test strains. Minimum inhibitory concentration (MIC) values were determined for the active compounds. Values of 5-8 µM results were obtained for the derivatives containing an octadecyl chain attached to the nitrogen atom, compared to values of 10-52 µM for the antibiotic gentamicin sulfate. These results shows great promise for modified sophorolipids in the medical sector, for example for the inhibition of biofilm formation.