a and b. The effect of ultrasonic pre-irradiation (at different power ratings) on lipase stability in aqueous media. pH tuned lipase (1 mg) in 0.1 M sodium phosphate buffer, pH 7.0 (100 μl) was sonicated at various power ratings (i.e 110 W, 66 W, 44 W) periodically. In this study, we carried out ultrasonication for 5 minutes, followed by a break of 10 minutes between each cycle. This ensured that the temperature of the sample could be maintained at 40 ± 1°C throughout. The value on the x-axis denotes the total time during which the ultrasonicator was 'on'. Samples were extracted at various intervals (i.e. 1, 2, 3, and 4 h) and an esterase assay was performed using pNPP as a substrate. Note: (a) Burkholderia cepacia lipase and (b) Pseudomonas fluorescens lipase. The experiments were carried out in triplicate. The error bar reflects the reproducibility for each data point.