Growth and Enzyme Activity of Lipolytic Bacteria Isolated from Degrading Oil Cakes

Abstract

Lipases are water soluble and industrially important enzymes and find application in the dairy industry, manufacturing detergents, pharmaceutical industries, etc. Lipases also have a potential role in waste management and biofuel production. They are acyl hydrolases and play a role in fat digestion by cleaving long-chain triglyceride into polar lipids. Due to the opposite polarity between the enzyme (hydrophilic) and their substrate (lipophilic), lipase reaction occurs at an interface between the aqueous and oil phase. In our previous study, we had isolated a few lipolytic strains from degrading oil cakes. They were microbiologically and biochemically characterized. Thirteen strains showed good lipolytic activity (Sarkar and Chatterji 2018). In this study, we further characterize these strains by growing them in different oil medium. Growth, cell count, and enzyme activity were assessed in nine different oil mediums (tributyrin, Tween 20, Tween 80, castor oil, coconut oil, olive oil, mustard oil, and used oil). Used oil was collected from the wok of a fried food street-side vendor. For growth and enzyme activity studies, a well-known lipase producing bacteria of the Pseudomonas species was taken as reference standard. While most of the thirteen strains showed reasonably good cell count in all the mediums used, isolated strain LC showed maximum activity in castor oil medium. In our previous study, stain LJ had shown maximum activity in standard growth medium (starch oil medium) for lipolytic bacteria. Though many other bacterial strains have reported higher activities, the lipase activity of strain LC was five times higher than the Pseudomonas species. Other stains like LA, LK, LG, LJ, and LH showed good activity in different oil mediums. This work helps in assessing the capacity of different strains in breaking down the fatty acids of different sizes. Thus, these lipolytic strains can find application in waste treatment and other relevant industries.