Nattokinase production: Medium components and feeding strategy studies

Abstract

In the present study, the effect of nutrients on nattokinase activity during the fermentation of Bacillus subtilis natto was investigated. The highest nattokinase activity of 587 U/mL was obtained in fermenter for a media consisting of yeast extract (6%, w/v), soy peptone (1.2%, w/v) and glycerol (6%, w/v). The second order polynomial equation was fitted to the results by using central composite face design. The polynomial model fitted the experimental data well with R2 = 0.939 and R2(Adj) = 0.861. In addition, contribution of fed-batch glycerol addition on the nattokinase production pathway was further investigated. Maximum nattokinase activity was resulted when 3% (w/v) glycerol was added to the fermentation media during the cell growth phase. Results demonstrate 25 fold increase of nattokinase activity compared to the batch and not optimized culture. This study provides valuable data on the key nutrients and feeding strategy for further investigations and scale up of nattokinase production process.