Regulation of environmental factors on the expression of a solid-state specific lipase (Lip1) with Rhizopus chinensis by western blot and indirect Elisa

To identify which solid-state typical environmental factors are involved in the induction of a solid-state special lipase (Lip1), western blot and Elisa based on Lip1 antibody were used. A low water activity played a significant role in the induction of Lip1, as evidenced by the increased expression level (20–46 μg/g dry cell) along with the decrease of water activity (0.927–0.969). Physical barrier against hyphal extension was found to be another required factor, since the expression of Lip1 was significantly enhanced by 3-fold using a membrane with smaller pore size (0.45 and 0.22 μm) covered on top of surface culture.