Isolation and Optimization of Growth Condition of Bacillus sp. from Fermented Shrimp Paste for High Fibrinolytic Enzyme Production

The fibrinolytic enzyme has been found in the traditional fermented foods including the traditional shrimp paste product. In this study, six Vietnamese traditional shrimp paste products collected in three regions (north, south and middle of Vietnam) were screened for fibrinolytic enzyme and the related bacteria were isolated and identified. The fibrinolytic enzyme was found in all Vietnamese shrimp paste products, in which the products in the middle of Vietnam had higher fibrinolytic enzyme activity (2.43–2.95 FU/ml) than those in other regions. The isolated bacterium which produced the highest fibrinolytic enzyme was identified as a strain of Bacillus sp., closely related to the species of Bacillus weihenstephanensis with 99 % identities. The optimal fermentation conditions were also investigated using response surface methodology based on Box–Behnken design for high fibrinolytic enzyme production by the isolated strain. As a result, the fibrinolytic enzyme activity reached to 6.85 FU/ml at the optimal fermentation condition of 1.50 % of shrimp shell powder, 1.44 % of NaCl, at 33 °C and 32-h fermentation. Thus, the fibrinolytic enzyme produced by the strain of Bacillus sp. in this study might be used as a thrombolytic agent in pharmaceutical industries.