Production and characterization of lipase fromPenicillium aurantiogriseumunder solid-state fermentation using sunflower pulp

Solid-State Fermentation (SSF) defined as a system in which the growth of microorganisms occurs on a moist solid substrate, shows tremendous potential in applications of microbial enzyme production as a low-cost, low-energy option. In this work, the production of lipase from Penicillium aurantiogriseum by using SSF was investigated. For this purpose, the sunflower pulp, an agro-industrial by-product, was utilized as a solid substrate in the SSF method. The optimization and characterization studies for lipase extract were performed by using the p-nitrophenyl palmitate (pNPP) (C16) as substrate. The lipase activity was found as 29.6 ± 0.11 U/mg protein at optimum conditions (50 mM of Tris-HCl buffer, pH 7.0, 40 °C). In thermal stability assay, the catalytic activities of lipase which are kept at 40, 50 and, 60 °C in a water bath for 1 h, were calculated as 100%, 60.48 ± 1.3%, 32.67 ± 0.2%, respectively. Also, the enzyme lost rapidly its activity within 15 min at 70 °C. The kinetic data, Km and Vmax, were determined as 0.17 mM and 2.9 µM/min, respectively. Also, 10 mM of Ba+2 ion had a slight activating effect (15%) showed on lipase. Lipase kept about 50% of its activity at 4 °C at the end of the 30 days. The hydrolytic activities of lipase for commercial olive oil and sunflower oil were found as 3.52 ± 0.1 U/mg and 3.90 ± 0.12 U/mg, respectively. The SSF method had obvious potential for the sustainable and cost-effective production of lipase from P. aurantiogriseum. Also, these results confirmed that the sunflower pulp could be used as an alternative substrate to produce enzymes in SSF conditions.