(572d) Influenced of Additive in the Post-Induction Phase on the Distribution of Phytase Expression By E. coli BL21 (DE3) When Induced with Lactose

Phytase is a type of phosphatase enzyme that mostly found in grain and seed that catalyzes the degradation of phytic acid realizing a useable form of inorganic phosphorus. A recombinant Escherichia coli BL21 (DE3) has been used for harboring thermostable phytase gene from Bacillus sp.MD2 and export the target protein to the periplasmic space. Lactose has been used as an alternative inducer in fermentation of recombinant E.coli. However, low productivity of protein expression was observed when induced with lactose due to the time needed by lactose to be transported into the cell by lactose permease and process to allolactose by β-galactosidase before binding to the repressor. To overcome this problem, the first approach used was by screening different types of additive such as Na⁺, Ca²⁺, glycine and Triton X-100 which was supplemented in the cultivation broth in the post-induction phase. Supplementation of only 10 mM of CaCl₂ can increased excretion of phytase outside the host cells membrane up to 33.63 % with the total productivity phytase activity only 673.75 U mL^-1 hr^-1 after 12 hours induced with 30 mM of lactose. In the other hand, supplementation combination of 10 mM of CaCl₂ with 0.5 % (w v^-1) of glycine in the post-induction phase did not shows drastically improved of extracellular and total phytase activity. However, the productivity of the total phytase production and extracellular phytase activity was increased up to 146.15 % and 119.9 %, respectively within 6 hours of post-induction phase. No improvement of volumetric phytase production rate was observed when 10 mM of CaCl₂ was combined with 0.5 % (w v^-1) of glycine in the pre-induction phase.