Lipolytic activity of lipases from different strains of Yarrowia lipolytica in hydrolysed vegetable fats at low temperature and water activity

Yarrowia lipolytica is a very important yeast because many strains from this yeast are able to produce the extracelular lipases. Cold active lipase is one of the important and widely used enzymes whose spectrum of applications has widened in many industries such as in detergent formulations, food industry, leather processing, environmental bioremediations, and fine chemical synthesis as well as in pharmaceutical industries. Cold active lipases are largely distributed in microorganisms surviving at low temperatures, near 4 °C. Although a number of lipase producing sources are available, only a few bacteria and yeasts were exploited for the production of cold active lipases. Attempts have been made from time to time to isolate cold active lipases from these microorganisms having high activity at low temperatures. These lipases show great interests in different applications of food and chemistry industry. In this study, it was evaluated the lipolytic activity of lipases from different strains of Yarrowia lipolytica in the critical conditions. The aim of this research was to evaluate the ability of different Yarrowia lipolytica strains, having different origin, to grow and to produce the lipases at low temperature (4°C). 13 Lipases from Yarrowia lipolytica coded as PO1, PO11, RO3, RO15, Y10, Y22, LP PAST to 1a, LC TL TO 4b, LP TQ to 1a, LN2, 1 II YL 4, 16B and 27D, were used for enzymatic hydrolysis of two crude exotic fats, like: white palm kernel fat and shea fat. The conditions of hydrolysis was a low temperature (4°C) and low values water activity (aw 0.98 and 0.96). The lipolytic activity of lipases was evaluated by measuring the diameters of hydrolysis zone. At 4°C and aw 0.98, the Yarrowia lipolytica strains such as : RO3, 1 II YL4 and LC TL to 4b produced the cold active lipases that had the higher lipolytic activity on the palm kernel fat. In the same conditions, lipases from yeast strains like: RO3, RO15 and 1 II YL4 demonstrated a strong lipolytic activity on the shea fat. At aw 0.96, the lipase produced by the same strains of Yarrowia lipolytica shows a higher specificity of palm kernel fat and shea fat.