Fig. 2

Optimization of the fermentation conditions of strain A3 for alginate lyase production by single factor method. A effects of fermentation temperature and time on the alginate lyase production. Strain A3 was cultured at 10, 15, 20, 25 or 30 °C in the basic fermentation medium. B effect of the content of L. japonica root powder on the alginate lyase production. Strain A3 was cultured in the medium containing 3% sea salts and different concentrations of L. japonica root powder (0.1, 0.25, 0.5, 0.75, 1 or 1.25%) at 20 °C for 24 h. C effects of inorganic nitrogen sources on the alginate lyase production. Strain A3 was cultured in the basic fermentation medium with an addition of 0.13% (w/v) NH₄Cl, NH₄HCO₃, NH₄NO₃ or (NH₄)₂SO₄ at 20 °C for 24 h. The alginate lyase production of strain A3 cultured in the basic fermentation medium at 20 °C for 24 h was taken as the control. D effect of the concentration of NH₄NO₃ on the alginate lyase production. Strain A3 was cultured in the basic fermentation medium containing different concentrations of NH₄NO₃ (0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 or 4%) at 20 °C for 24 h