Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
Medium optimization for 5’-phosphodiesterase production from Penicillium citrinum was studied by applying one-factor-at-a-time method, orthogonal array method and response surface methodology in this paper. The one-factor-at-a-time method was used to study the effects of carbon, nitrogen, phosphorus and metal ion sources on 5’-phosphodiesterase production. Among various carbon and nitrogen sources used, glucose and peptone were the most suitable substances for 5’-phosphodiesterase production, respectively. Subsequently, the concentrations of glucose, peptone, groundnut meal, Zn2+ and KH2PO4 were optimized using the orthogonal array method. Response surface methodology was also applied for medium optimization. Glucose concentration (X1), peptone concentration (X2) and groundnut meal (X3) were selected as the independent variables. Results showed that the regression models adequately explained the data variation and represented the actual relationships between the parameters and responses. The optimum conditions were glucose at a fraction of 6.5 %, peptone at a fraction of 0.45 % and groundnut meal at a fraction of 1.0 %. Maximum enzyme activity was 353 U/mL under the optimum conditions. Maximum 5’-phosphodiesterase activity in media optimized by orthogonal method and response surface methodology was about 1.286 and 1.456 times, respectively, greater than in the medium optimized by one-factor-at-a-time method.U ovom je radu provedeno optimiranje podloge za proizvodnju 5\u27-fosfodiesteraze iz plijesni Penicillium citrinum trima metodama: jednofaktorskom, ortogononalnom i metodom odzivnih površina. Primjenom jednofaktorske metode istražen je utjecaj izvora ugljika, dušika, fosfora i iona metala na proizvodnju 5\u27-fosfodiesteraze. Upotrijebljeni su razni izvori ugljika i dušika, među kojima su glukoza i pepton bili najprikladniji za proizvodnju 5\u27-fosfodiesteraze. Nakon toga su, primjenom ortogonalne metode, optimirane koncentracije glukoze, peptona, sačme od neoljuštena orašca, Zn2+ iona i KH2PO4. Optimiranje podloge provedeno je i metodom odzivnih površina. Kao nezavisne varijable određene su koncentracija glukoze (X1), peptona (X2) i sačme orašca (X3). Pokazalo se da su regresijski modeli bili najprikladniji za objašnjenje rezultata i prikazivanje stvarnog odnosa parametara i odziva. Optimalni su uvjeti postignuti s udjelom glukoze od 6,5 %, peptona 0,45 % i sačme orašca 1,0 %. Maksimalna aktivnost enzima 5\u27-fosfodiesteraze u optimalnim uvjetima iznosila je 353 U/mL, te je u podlozi optimiranoj ortogonalnom metodom bila 1,286 puta veća, a metodom odzivnih površina 1,456 puta veća nego u podlozi optimiranoj jednofaktorskom metodom
