Prolonged Production and Aggregation Complexity of Cold-Active Lipase from Pseudomonas proteolytica (GBPI_Hb61) Isolated from Cold Desert Himalaya

Pseudomonas, being the common inhabitant of colder environments, are suitable for the production of cold-active enzymes. In the present study, a newly isolated strain of Pseudomonas from cold desert site in Indian Himalayan Region, was investigated for the production of cold-active lipase. The bacteria were identified as Pseudomonas proteolytica by 16S rDNA sequencing. Lipase production by bacteria was confirmed by qualitative assay using tributyrin and rhodamine-B agar plate method. The bacterium produced maximum lipase at 25 °C followed by production at 15 °C while utilizing olive, corn, as well as soybean oil as substrate in lipase production broth. Enzyme produced by bacteria was partially purified using ammonium sulphate fractionation. GBPI_Hb61 showed aggregation behaviour which was confirmed using several techniques including gel filtration chromatography, dynamic light scattering, and native PAGE. Molecular weight determined by SDS-PAGE followed by in-gel activity suggested two lipases of nearly similar molecular weight of ~50 kDa. The enzyme showed stability in wide range of pH from 5 to 11 and temperature up to 50 °C. The enzyme from GBPI_Hb61 exhibited maximum activity toward p-nitrophenyldecanoate (C10). The stability of enzyme was not affected with methanol while it retained more than 75% activity when incubated with ethanol, acetone, and hexane. The bacterium is likely to be a potential source for production of cold-active lipase with efficient applicability under multiple conditions.