Optimisation, purification and characterisation of extracellular lipase from Botryococcus sudeticus (UTEX 2629)

Abstract

Lipases are ubiquitous esterase enzymes which have many industrial and environmental applications. Currently, bacterial and fungal lipases have been widely studied and researched for biodiesel production. However, the cost of production for those enzymes is still high and the efficiencies of the enzymes are moderate. Alternative producers need to be explored. In this paper, extracellular lipase of Botryococcus sudeticus UTEX 2629 (B. sudeticus) was isolated and studied. This is the first time lipase isolated from B. sudeticus is reported. The optimum lipase production condition was analysed by incubating B. sudeticus in various types of oil (palm, corn, canola and olive oils) and under different agitation effects. The highest lipase production was found in the olive oil containing medium with the presence of agitation. The molecular mass of the purified lipase was estimated to be approximately 120kDa. The kinetic properties of the purified lipase were determined and the values for Vmax and Km of the purified lipase were 33.00μmolmin−1mg−1 and 2.02mM respectively. The lipase was active in high temperatures ranging from 40 to 70°C and in alkaline buffers from pH 10 to 11. It showed maximal activity at 50°C and pH 10. There was stable and enhanced activity after 12h pre-incubation at 30°C. The lipase has highest specificity for the medium alkyl chain substrate. Finally, metal ions FeSO4, MnSO4, NaCl, ZnCl and ZnSO4 and reagents SDS, EDTA, PMSF, ethanol and isopropanol were found to enhance enzyme activity.