Production of glucolipids and specialty fatty acids from sophorolipids by Penicillium decumbens naringinase: Optimization and kinetics

In view of global environmental concerns and the awakening to the exhaustibility of our natural resources, an increasing importance of biologically derived surfactants can be expected in the near future. Enzymatic modification of these biosurfactants allows to improve their characteristics and so extend their application field. In view of this, glucolipids are interesting substrates e.g., for the synthesis of new glycolipids with increased biological activity. Here, we describe the optimization of glucolipid production from Candida bombicola sophorolipids by Penicillium decumbens naringinase and show that the enzyme might be useful for production of specialty fatty acids as well. Optimum conditions for production of glucolipids were found to be pH 7.0 and 50°C with a yield of 80% (w/w) glucolipids after 3 h of incubation. The K_m for sophorolipids was 1.67 mM, while V_max was 0.035 mM sophorolipids/min. At pH 3.0, glucolipids were immediately further hydrolyzed and completely converted to fatty acids after 24 h of incubation, offering a biological route to the synthesis of unique specialty fatty acids. The K_m for glucolipids was 11 mM while V_max was 0.21 mM glucolipids/min. Glucose inhibited the enzyme in a competitive way with K_I around 10-15 mM glucose. Surfactant properties of the produced glucolipids were comparable to those of the acidic sophorolipids.