A fungal microorganism can be engineered by means of genetic engineering to utilise L-arabinose. The genes of the L-arabinose pathway, which were unknown, i.e. L-arabinitol 4-dehydrogenase and L-xylulose reductase, were identified. These genes, together with the known genes of the L-arabinose pathway, form a functional pathway. This pathway can be introduced to a fungus, which is completely or partially lacking this pathway.