Kawther Isam Eldeen¹, Hanan Moawia Ibrahim^1,, Elrashied Elimam Elkhidir², Hassan Beshir Elamin³

This study was conducted with the aim to isolate, characterize and optimize of Bacillus subtilis that produce nattokinase with highest activity under optimal culture conditions. The study was carried out on 25 samples collected from different regions in Khartoum. Primary screening and characterization of the microorganism showed that seven out of 25 samples (28%) were presumptively considered Bacillus subtilis according to microscopic and biochemical analysis. The promising isolates produced an extracellular crude nattokinase indicating by heamolytic and fibrinolytic activity. Selective medium was prepared for the extraction and production of nattokinase from these new isolates. Optimization of enzymatic production using statistical experimental design was carried out using central composite design (CCD) in response to surface methodology (RSM) to achieve the maximum nattokinase yield such as temperature and pH in shake flask culture from Bacillus spp. The optimal conditions for maximum enzyme production were found to be of 45°C and pH of 5.0. This study reveals that under optimized conditions, nattokinase yield was significantly increased which was higher than earlier reports and promises the use of RSM as an efficient tool for nattokinase production

optimization, nattokinase, RSM, fibrinolytic activity