GALLY PROOF 1 11777 5 6 7 8 9 10 11 12 INTRODUCTION Catalase is a common enzyme which is found nearly in all living organisms which are exposed to oxygen, where the function of the catalase is to decompose the hydrogen perox- ide into water and oxygen (Chelikani 2004). In food industry catalase is used to remove hydrogen peroxide from milk pre- ceding to cheese manufacturing (Worthington 2009). Cata- lase is also used in textile industry for the removal of the hy- drogen peroxide to make sure that the fabric is peroxide-free (Case study 2009). Millions of molecules of hydrogen perox- ide can be converted into water and oxygen by a single mol- ecule of catalase (Goodsell DS 2004). A minute use is in the lenses is that, some cleaning products for lenses are having hydrogen peroxide and to use lens again a catalase containing solution is used for the decomposition of hydrogen peroxides (Cook JN 1996). Now a day's catalase is used in the aesthetics industry. Commercially catalase is produced from Aspergil- lus niger being a GRAS (generally regarded as safe) organ- ism. Aspergillus niger is extensively used for the purpose of mutagenesis. Activity of catalase increases with the positive impact of mutation on active site of catalase. In the present study isolated and pure cultures of Aspergillus niger were ob- tained and observed the activity of wild type of strain then caused the mutation in Aspergillus niger by ultra violet (UV) and nitrous acid and then observed the effect of mutation on catalase production. Effects of Physical Mutagen on Catalase Production MUHAMMAD SALMAN MUHSAN * , ANEELA AHMED and SHAZIA KHURSHID Department of Chemistry, Government College University Lahore, Pakistan *Corresponding author: E-mail: salo_gcu@yahoo.com Asian Journal of Chemistry; Vol. 23, No. 12 (2011), 0000-0000 Received: ; Accepted: ) AJC 0000 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 The present study deals with the effects of physical mutagen on the production of catalse. The ultra violet radiations were used as a physical mutagen. The effect of nitrous acid mutation on the catalase production was also observed. Some fermentation conditions such as fermentation period, concentration of substrate, pH, temperature, concentration of urea and KH2PO4 were optimized. It was resulted that activity of catalase from Aspergillus niger was maximum at 40 h of incubation, 8.0 % of glucose concentration (3.40 units/mg), at 30 ºC, at pH 7.0, at 0.2 % of urea concentration, at 0.4 % of KH2PO4. The mutation of nitrous acid decreased the catalase activity. Maximum activity of catalase after ultra violet mutation, was found in mutant number 8.0 that was 5.983 unit/mg, which was exposed for 40 min under ultra violet lamp. Key Words: 1 2 3 4 EXPERIMENTAL Substrate: For the growth production of catalase the sub- strate used was glucose. Glucose serves as the carbon source for production the production catalase. Organism: The fungal species of Aspergillus niger were used for this kind of study and taken from the process devel- opment lab of Chemistry Department of G.C. University Lahore. The fresh strains of Aspergillus niger were developed on potato dextrose agar (PDA) 30 ºC for 24 h in incubator and stored at 4C in cold cabinet. Inoculation: Inoculated the slants with the fresh strain of Aspergillus niger with help of inocculum needle. Then incu- bated the slants in the incubator at 37 ºC for 24 h. After every two weeks. Propagation of strain on the fresh medium was continued. After incubation these pure and identified colonies of Aspergillus niger were stored in cold incubator/refrigerator at 4 ºC. Submerged fermentation methodology: For the produc- tion of catalase from Aspergillus niger, the submerged fer- mentation was applied. The fermentation medium was used in 250 mL shake flasks. The composition of fermentation me- dium was as followed, 12.5 g of NaNO3, 1.25 g of MgSO4·7H2O, 0.025 g of FeSO4·7H2O, 2.5 g of KH2PO4, 25 g of glucose, 1.75/25 mL H2O of CaCO3, 0.2 g of urea. The compound's composition used in flask was as follows, 1.75 g/ 25 mL of CaCO3, 10 mL of glucose, 2 mL of urea, 2 mL of 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62