Optimization of acid protease production by Aspergillus niger II on shrimp peptone using statistical experimental design

• Published in: TheScientificWorld 2012-01, Vol.12
• Main Authors: Siala, Rayda, Frikha, Fakher, Mhamdi, Samiha, Nasri, Moncef, Kamoun, Alya Sellami
• Format: Article
• Language: English
• Subjects: Aspergillus; Genetic aspects; Microorganisms; Physiological aspects; Proteases
• ISSN: 1537-744X; 1537-744X
• DOI: 10.1100/2012/564932

Medium composition and culture conditions for the acid protease production by Aspergillus niger I1 were optimized by response surface methodology (RSM). A significant influence of temperature, K[H.sub.2]P[O.sub.4], and initial pH on the protease production was evaluated by Plackett-Burman design (PBD). These factors were further optimized using Box-Behnken design and RSM. Under the proposed optimized conditions, the experimental protease production (183.13 U [mL.sup.-1]) closely matched the yield predicted by the statistical model (172.57 U [mL.sup.-1]) with [R.sup.2] = 0.914. Compared with the initial M1 medium on which protease production was 43.13 U [mL.sup.-1], a successful and significant improvement by 4.25 folds was achieved in the optimized medium containing (g/L): hulled grain of wheat (HGW) 5.0; K[H.sub.2]P[O.sub.4] 1.0; NaCl 0.3; MgS[O.sub.4](7[H.sub.2]O) 0.5; Ca[Cl.sub.2] (7[H.sub.2]O) 0.4; ZnS[O.sub.4] 0.1; [Na.sub.2]HP[O.sub.4] 1.6; shrimp peptone (SP) 1.0. The pH was adjusted at 5 and the temperature at 30°C. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, HGW and SP, which may result in a significant reduction in the cost of medium constituents.