Co‐production of nattokinase and α ‐amylase from Bacillus natto fermentation using okara

Effective use of okara (soybean residue) requires more application aspects to increase its value. The production of enzyme preparations by okara fermented may be an effective approach. In this paper, Bacillus natto was used in okara fermentation to investigate the production of certain enzymes including nattokinase. The results showed that the fermented okara by B. natto produced a large amount of nattokinase and α-amylase. After the response surface optimization, the nattokinase activity(189.3 IU/mg) and the α-amylase activity (7.8 U/mg) were obtained at the 36 h fermentation time, the rotation speed 170 rpm, the inoculation amount 9%. After simple two-step purification, ammonium sulfate precipitation and Sephadex G-200 column chromatography, the activities of these two enzymes reached 1663.9 IU/mg and 39.93 U/mg, respectively. In short, this research provides a theoretical basis for expanding the application of okara as a low-cost enzyme preparation. Novelty impact statement The co-production of nattokinase and α-amylase from fermented okara by Bacillus natto can effectively increase the added value of okara. Meanwhile this research provides a theoretical basis for expanding the application of okara as a low-cost enzyme preparation.