Document Type : Original Article
Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
Catalase is an antioxidant enzyme that has various applications in different industries, such as food, dairy, textile, etc. Alkaline catalase is suitable in this regard. Kocuria sp. ASB107 is a radio-resistant bacterium that has been isolated from Ab-e-siahspring in Ramsar (Mazandaran Province, Iran). This bacterium is able to produce relative high amounts of alkaline catalase and hence this catalase has the potential for industrial applications. Production of enzyme in a short time and with low expenses is of a great importance. Lag phase of Kocuria sp. ASB107 growth takes a long time in TSB medium (about 13 hours). In order to achieve the highest rate of bacterial growth, 5% inoculum size of cells was used in the middle logarithmic phase and as a result, bacterial lag phase decreased to 2 hours. On the other hand, for economic production of catalase, sugar beet molasses was used as a cheap carbon source. Several factors effecting bacterial growth and enzyme activity were selected for the optimization of catalase production by Kocuria sp. ASB107 using Response Surface Methodology (RSM) based on the Central Composite Design (CCD). Four variables (carbon source, nitrogen source, agitation, and inoculum size) were selected for the optimization studies. Results showed that Kocuria sp. ASB107 exhibits optimum rate of catalase activity (3399.08 U/ml) and bacterial biomass (6.904 g/L) with carbon source 3% v/v, nitrogen source 0.5% w/v, inoculum size 7.5% v/v, and agitation 200 rpm.