Lipase production with free and immobilized cells of cold-adapted yeast Rhodotorula glutinis HL25

•A new cold-adapted yeast strain with high lipase activity was isolated and identified.•Free and immobiized cells of the yeast was used for lipase production.•Waste frying olive oils was used as substrate for lipase production.

This study was undertaken to produce the lipase by free and immobilized cells of cold-adapted yeast Rhodotorula glutinis HL25 using waste frying oils as substrate. The optimization of culture parameters was performed using traditional one-factor-at-a-time protocol. The temperature 20 °C and initial pH 6.0 were optimal for lipase production by both free and immobilized cells. An inoculum size of 40 mL/L for free cells and beads number of 150 g/L for immobilized cells were optimal for lipase production. Optimal waste frying oil concentration and incubation time were 30 mL/L and 84 h for free cells but 40 mL/L and 72 h for immobilized cells, respectively. The maximum increases for free and immobilized cells were achieved at the Triton X-100 concentrations of 5 and 7.5 mL/L, respectively. The maximum lipase activities were determined as 54.4 and 75.2 U/L for free and immobilized cells, respectively. Immobilized cells could be used in five successive reaction cycles without any loss in the maximum activity. Immobilized cells could retained about 70% of their maximum activity by the end of the cycle 10. This is the first attempt on lipase production potential of a cold-adapted strain of the yeast R. glutinis. Furthermore, lipase production using immobilized cells of cold-adapted yeasts was investigated for the first time.