Background: Depletion of petroleum resources has enforced the search for alternative sources of renewable energy. Introduction of biofuels onto the market was expected to become a solution to this disadvantageous situation. Attempts to cover fuel demand have, however, caused another severe problem - a waste glycerol generated during biodiesel production in the quantity of ca. 10% w/w. This, in turn, prompted a global search for effective methods of valorization of the waste fraction of glycerol.

Results: The 48 h utilization of the waste fraction with the initial glycerol concentration of 30 gL^-1, proceeding with 62% efficiency, enabled producing dihydroxyacetone with the concentration of 9 gL^-1, at 50% substrate consumption. The re-use of the immobilized biocatalyst allowed achieving a similar concentration of dihydroxyacetone (8.7 gL^-1) in two-fold shorter time at the efficiency of 85% and lower substrate consumption (35%).

Conclusions: The method proposed in this work is based on conversion of the waste glycerol to dihydroxyacetone in the reaction catalyzed by an immobilized cell extract with the activity of glycerol dehydrogenase, produced from Gluconobacter oxydans bacteria and it could be an effective way to utilize the waste glycerol into a valuable product.