Abstract: Both one factor at atime method and response surface methodology were used toenhance the spore content ofBacillus subtilis NHS1 in fermentation broth. A response surfaceregression equation was established based on the results of onefactor at atime, PlackettBurman, steepest ascent and Box-Behnken experimental designs. The optimal mediumformulation, as predicted from the equation, consisted of 1.88 g·L^-1 starch, 6.83 g·L^-1 NaCl, 5.60 g·L^-1 corn flour, 10 g·L^-1 yeast extract powder, 10 g·L^-1 peptone, 15 g·L^-1 beefextract, 2 g·L^-1 glucose, 3 g·L^-1 MgSO₄. The yield of the spore reached 2.42×10⁹cfu·mL^-1, which was 1.5fold higher than that before the optimization by using the optimized medium at36 ℃ with shaking at a speed of 170 r·min^-1 for 72 h.

Key words: deep profiles, HYDRUS-1D model, Weibei rainfed highland, soil moisture