Co-production of nattokinase and poly (γ-glutamic acid) under solid-state fermentation using soybean and rice husk

The aim of this work was to study the co-production of nattokinase and poly (γ-glutamic acid) by Bacillus subtilis natto with soybean and rice husk under solid-state fermentation (SSF). The results showed that the size of soybean particle and rice husk significantly improved the co-production of nattokinase and poly (γ-glutamic acid), yielding 2503.4 IU/gs and 320 mg/gs, respectively in the improved culture medium composed of 16.7% soybean flour and 13.3% rice husk with 70% water content. The yields increased by approximate 7- and 2-fold factor relative to their original ones. Thus, the co-production of nattokinase and poly (γ-glutamic acid) under SSF could be considered as an efficient method to exploit agro-residues for economical production of some higher-value products.