Fuente: WIPO "tomato" The present invention is in the technical field of synthetic biology, metabolic engineering and cell cultivation. The invention describes advantageous mutants of a reference beta beta-1,3-N- acetylglucosaminyltransferase represented by SEQ ID NO 01, as well as a cell comprising said mutant beta- 1,3-N-acetylglucosaminyltransferase. The invention further describes methods for the production of a lacto-N-triose II (LN3)-containing oligosaccharide or a mixture comprising at least two different LN3- containing oligosaccharides, wherein a beta-1,3-N-acetylglucosaminyltransferase mutant is used (optionally present in a cell).