Valorization of Waste Glycerol to Dihydroxyacetone with Biocatalysts Obtained from <i>Gluconobacter oxydans</i>

Waste glycerol is the main by-product generated during biodiesel production, in an amount reaching up to 10% of the produced biofuel. Is there any method which allows changing this waste into industrial valuable compounds? This manuscript describes a method for valorization of crude glycerol via microbial bioconversion. It has been shown that the use of free and immobilized biocatalysts obtained from Gluconobacter oxydans can enable beneficial valorization of crude glycerol to industrially valuable dihydroxyacetone. The highest concentration of this compound, reaching over 20 g&#183;L&#8722;1, was obtained after 72 h of biotransformation with free G. oxydans cells, in a medium containing 30 or 50 g&#183;L&#8722;1 of waste glycerol. Using a free cell extract resulted in higher concentrations of dihydroxyacetone and a higher valorization efficiency (up to 98%) compared to the reaction with an immobilized cell extract. Increasing waste glycerol concentration to 50 g&#183;L&#8722;1 causes neither a faster nor higher increase in product yield and reaction efficiency compared to its initial concentration of 30 g&#183;L&#8722;1. The proposed method could be an alternative for utilization of a petrochemical waste into industry applicated chemicals