3.8.2. The Biotransformation Medium Was Studied by Single-Factor Experiment and Orthogonal Experiment

On the basis of the best cosolvent, the nitrogen source, carbon source, and initial pH were studied by a single-factor experiment. The 30 g/L sucrose in the transformation medium was replaced with glucose, mannitol, lactose, maltose, starch, etc. of the same concentration to explore the effect of carbon sources on the transformation yield. And then, the carbon source concentration in the transformation medium was set to 10 g/L, 20 g/L, 30 g/L, 40 g/L, 50 g/L to explore the effect of carbon source concentration on the transformation rate. The 10 g/L yeast extract in the transformation medium was replaced with sodium nitrate, ammonium sulfate, peptone, yeast extract powder, and beef extract of the same concentration to explore the effect of the nitrogen source on the transformation rate. The concentration of nitrogen source in the transformation medium was set to 5 g/L, 10 g/L, 15 g/L, 20 g/L, and 30 g/L to explore the effect of nitrogen source concentration on the transformation rate. Set the initial pH of the transformation medium to 4.5, 5.5, 6.5, 7.5, or 8.5 and explore the impact of different initial pH values on the transformation yield.

According to the results of the single-factor experiment, an orthogonal experiment with three factors and three levels L<sup>9</sup> (3<sup>3</sup> ) was designed.
